JPH0627218U - Vehicle suspension - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a vehicle suspension system capable of improving the control responsiveness while ensuring the riding comfort of the vehicle, obtaining sufficient vibration damping property against a large road surface input, and improving the steering stability. [Configuration] When the control signal is less than a predetermined large input threshold value, the value of the basic threshold value indicates the maximum attenuation characteristic between the time when the control signal reverses the direction and the predetermined basic threshold value is reached. Attenuation characteristic control is performed in proportion to the control signal so that the control signal value is updated to the basic threshold value until the peak value is reached when the threshold value is exceeded, and the direction of the control signal from the peak value is changed. Until the reverse direction, the basic control unit d that performs the damping characteristic control in proportion to the control signal having the peak value of the control signal as the maximum damping characteristic and the control after that when the control signal exceeds the large input threshold value Until the direction of the signal is reversed, there is provided a correction control unit f for performing the attenuation characteristic control based on a value obtained by multiplying the result of the attenuation characteristic control by the basic control unit d by a predetermined constant larger than 1.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a vehicle suspension system that optimally controls the damping characteristics of a shock absorber.

[0002]

[Prior art]

 Conventionally, as a vehicle suspension system for controlling the damping characteristic of a shock absorber, for example, one disclosed in Japanese Utility Model Laid-Open No. 63-93203 is known. This conventional vehicle suspension system detects the sprung vertical speed and the relative speed between the sprung and unsprung parts, and when both have the same sign, the damping characteristic is made hard, and when the two have different signs, the damping characteristic is soft. The damping characteristic control based on the skyhook theory, such as the above, was performed independently for the four wheels.

[0003]

[Problems to be solved by the device]

 However, since the above-mentioned conventional device has the above-mentioned configuration, if a high control gain is set so as to obtain sufficient vibration damping for road surface input, low frequency road surface input However, the response is too high for high-frequency road surface input, and the unsprung input is transmitted to the sprung, which deteriorates the riding comfort of the vehicle. Also, if the control gain is set to a low value so that the ride comfort of the vehicle can be secured, there arises a problem that sufficient damping performance cannot be obtained for a large road surface input.

In the conventional damping characteristic control based on the skyhook theory, the actuator is driven to switch the damping characteristic each time the signs of both the sprung vertical velocity and the relative velocity are changed. Since this has been necessary, there is a problem that the control response becomes poor and the number of times the actuator is driven increases, which lowers the durability.

The present invention has been made by paying attention to the above-mentioned conventional problems, and it is possible to secure the ride comfort of the vehicle while improving the control responsiveness, and at the same time, it is possible to sufficiently control the vibration of a large road surface input. The first purpose is to provide a vehicle suspension system that can improve the steering stability and to provide a vehicle suspension system that can improve the control response and the durability of the actuator. Has an aim.

[0006]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the vehicle suspension system according to claim 1 of the present invention is interposed between the vehicle body side and each wheel side by the damping characteristic changing means a as shown in the claim correspondence diagram of FIG. The shock absorber b whose damping characteristic can be changed, the sprung vertical velocity detecting means c for detecting the sprung vertical velocity, and the control when the control signal based on the sprung vertical velocity is less than a predetermined large input threshold value From the time the signal reverses its direction until it reaches the specified basic threshold value, the damping characteristic control is performed in proportion to the control signal so that the maximum damping characteristic is achieved at the basic threshold value, and the basic threshold value is exceeded. Then, the control signal value is updated to the basic threshold value until the peak value is reached, and the peak control signal value is taken as the maximum attenuation characteristic until the direction of the control signal is reversed from the peak value. Proportional to the control signal When the control signal e is provided in the control means e having the basic control unit d for performing the attenuation characteristic control, and the control signal becomes equal to or higher than the large input threshold value, the direction of the control signal is reversed until the direction is reversed. A means is provided with a correction control unit f for performing the damping characteristic control based on a value obtained by multiplying the damping characteristic control result by the basic control unit d by a predetermined constant greater than 1.

In addition to the above configuration, the vehicle suspension system according to a second aspect of the present invention is characterized in that, in addition to the above-mentioned configuration, the shock absorber includes an expansion side hard region in which the expansion side has a variable damping characteristic and the compression side has a low damping characteristic and the compression side has a damping characteristic It is formed in a structure having three regions, a compression side hard region where the characteristic is variable and the expansion side is fixed to the low damping characteristic, and a soft region where the expansion side and the compression side both have the low damping characteristic. When the value is positive, the shock absorber is controlled in the expansion side hard area, when the control signal is negative, the shock absorber is controlled in the pressure side hard area, and when the control signal is 0, the shock absorber is controlled in the soft area. Configured to do so.

[0008]

[Action]

 Since the vehicle suspension system of the present invention is configured as described above, when the road surface input is small, the control signal based on the sprung vertical velocity is less than the predetermined large input threshold value. Until the control signal reverses its direction and reaches a predetermined basic threshold value, the damping characteristic control is performed in proportion to the control signal so that the maximum damping characteristic is obtained at the basic threshold value, and the basic threshold value is set. When it exceeds the value, the control signal value is updated to the value of the basic threshold value until the peak value is reached.By this, the control sensitivity is maintained while maintaining the predetermined sensitivity in the initial stage of the rise of the damping force. In addition, the proportional control of the damping characteristics is performed with the peak value of the control signal value as the maximum damping characteristic between the peak value and the direction of the control signal being reversed. Sudden increase in damping force It is possible to ensure the ride comfort of the vehicle by eliminating the change.

Further, when the road surface input becomes large, the control signal becomes equal to or higher than the large input threshold value. Therefore, in the correction control unit, until the direction of the control signal is reversed thereafter, the damping characteristic by the basic control unit is reduced. The damping characteristic control is performed based on the value obtained by multiplying the control result by a predetermined constant greater than 1, and as a result, the time for maintaining the maximum damping characteristic is extended compared to when the damping characteristic control is performed by the basic control unit. As a result, it is possible to obtain sufficient damping performance for a large road surface input and to secure the steering stability of the vehicle.

Further, in the apparatus according to claim 2, when the control signal has a positive value, the shock absorber is controlled in the expansion side hard region (the compression side is fixed to the low damping characteristic), and when the control signal has a negative value. The shock absorber is controlled in the compression side hard area (fixed to the low damping characteristic on the extension side), and when the control signal is 0, the shock absorber is controlled in the soft area. Therefore, the control signal based on the sprung vertical speed is used. When the relative speed between the sprung part and the unsprung part has the same sign, the stroke side of the shock absorber at that time is controlled to the hard characteristic, and when the sign is different, the stroke side of the shock absorber at that time is set to the soft characteristic. The same control as the damping characteristic control based on the skyhook theory can be performed without detecting the relative speed between the sprung and unsprung parts. Since the characteristics are switched without driving the actuator, the frequency of switching the damping characteristics is reduced compared to the conventional damping characteristics control based on the skyhook theory, improving control response and improving actuator durability. And can be planned.

[0011]

【Example】

Embodiments of the present invention will be described with reference to the drawings. First Example First, the configuration will be described. 2 is a structural explanatory view showing a vehicle suspension system of a first embodiment which is an embodiment of the invention described in claims 1 and 2, and is interposed between a vehicle body and four wheels, and four shock absorbers are provided. Quark absorbers SA ₁ , SA ₂ , SA ₃ , SA ₄ (In describing shock absorbers, when referring to these four collectively, and when describing their common configuration, simply refer to SA.) Is provided. A vertical acceleration sensor (hereinafter referred to as a vertical G sensor) 1 for detecting vertical acceleration is provided on the vehicle body near each shock absorber SA. Further, at a position near the driver's seat, there is provided a control unit 4 which inputs a signal from each vertical G sensor 1 and outputs a drive control signal to the pulse motor 3 of each shock absorber SA.

FIG. 3 is a system block diagram showing the above configuration. The control unit 4 includes an interface circuit 4a, a CPU 4b, and a drive circuit 4c, and the interface circuit 4a includes the above-mentioned vertical G sensors 1 And a signal from the vehicle speed sensor 5 is input. In the interface circuit 4a, a set of five filter circuits shown in FIG. 14 is provided for each upper and lower G sensor 1. That is, the LPF 1 is a low-pass filter circuit for removing noise in the high frequency range (30 Hz or higher) from the signal sent from the upper and lower G sensors 1. The LPF2 is a low-pass filter circuit for integrating a signal indicating the acceleration that has passed through the low-pass filter circuit LPF1 and converting it into a sprung vertical velocity. BPF1 is only passes the frequency range including the sprung resonance frequency bouncing component signal _{v (v 1, v 2,} v 3, v 4 The numbers _{1, 2, 3, and 4} positions of the shock absorbers SA The same applies to the following.) Is a bandpass filter circuit that forms The BPF ₂ is a bandpass filter circuit that passes a frequency range including a pitch resonance frequency and forms a pitch component signal v ′ (v ₁ ′, v ₂ ′, v ₃ ′, v ₄ ′). The BPF ₃ is a bandpass filter circuit that forms a roll component signal v ″ (v ₁ ″, v ₂ ″, v ₃ ″, v ₄ ″) by passing a frequency range including the roll resonance frequency. In the embodiment, the case where the sprung resonance, the pitch resonance, and the roll resonance frequencies are different is taken as an example, but when these resonance frequencies are close to each other, the band pass filter is only BPF1.

Next, FIG. 4 is a sectional view showing the structure of the shock absorber SA. The shock absorber SA includes a cylinder 30, and a piston 31 defining the cylinder 30 into an upper chamber A and a lower chamber B. And an outer cylinder 33 having a reservoir chamber 32 formed on the outer periphery of the cylinder 30, a base 34 defining the lower chamber B and the reservoir chamber 32, and a slide of the piston rod 7 connected to the piston 31. It includes a guide member 35, a suspension spring 36 interposed between the outer cylinder 33 and the vehicle body, and a bumper bar 37.

Next, FIG. 5 is an enlarged cross-sectional view showing a portion of the piston 31. As shown in FIG. 5, the piston 31 has through holes 31a and 31b formed therein, and A compression side damping valve 20 and an expansion side damping valve 12 for opening and closing the holes 31a and 31b are provided. A stud 38 penetrating the piston 31 is screwed and fixed to a bound stopper 41 screwed to the tip of the piston rod 7, and the stud 38 bypasses the through holes 31a and 31b. For forming a flow path (an expansion-side second flow path E, an expansion-side third flow path F, a bypass flow path G, and a compression-side second flow path J, which will be described later) that connects the upper chamber A and the lower chamber B to each other. A communication hole 39 is formed, and an adjuster 40 for changing the flow passage cross-sectional area of the flow passage is rotatably provided in the communication hole 39. Further, on the outer peripheral portion of the stud 38, there are provided an extension side check valve 17 and a pressure side check valve 22 which allow or block the flow passage side flow passage formed by the communication hole 39 depending on the direction of fluid flow. Has been. The adjuster 40 is rotated by the pulse motor 3 via the control rod 70 (see FIG. 4). Further, the stud 38 is formed with a first port 21, a second port 13, a third port 18, a fourth port 14, and a fifth port 16 in order from the top.

On the other hand, in the adjuster 40, a hollow portion 19 is formed, a first lateral hole 24 and a second lateral hole 25 which communicate the inside and the outside are formed, and a vertical groove 23 is formed in the outer peripheral portion. It

Therefore, between the upper chamber A and the lower chamber B, as a flow path through which the fluid can flow in the extension stroke, the inside of the extension side damping valve 12 is opened by passing through the through hole 31b. The expansion side first flow path D leading to B and the expansion side damping valve 12 opening the outer peripheral side through the second port 13, the vertical groove 23, and the fourth port 14 to reach the lower chamber B An expansion side third flow path F that opens the expansion side check valve 17 through the second port E, the second port 13, the vertical groove 23, and the fifth port 16 to reach the lower chamber B; There are four flow paths, a bypass flow path G, which reaches the lower chamber B via the third port 18, the second lateral hole 25, and the hollow portion 19. Further, as a flow path through which the fluid can flow in the pressure stroke, the pressure side first flow path H that opens the pressure side damping valve 20 through the through hole 31a, the hollow portion 19, the first lateral hole 24, and the first port 21. The pressure-side second flow path J that opens the pressure-side check valve 22 to the upper chamber A via the bypass, and the bypass to the upper chamber A via the hollow portion 19, the second lateral hole 25, and the third port 18. There are three flow paths G and G.

That is, the shock absorber SA is configured such that the damping characteristic can be changed in multiple stages on both the extension side and the compression side with the characteristics shown in FIG. 6 by rotating the adjuster 40. That is, as shown in FIG. 7, when the adjuster 40 is rotated counterclockwise from a state in which both the expansion side and the compression side are soft (hereinafter referred to as the soft region SS), the damping characteristics only in the expansion side have multiple stages. It can be changed and the compression side becomes a region fixed to the low damping characteristic (hereinafter referred to as the extension side hard region HS). Conversely, when the adjuster 40 is rotated clockwise, only the compression side can change the damping characteristic in multiple stages. The structure is such that the extension side is a region fixed to the low damping characteristic (hereinafter referred to as the compression side hard region SH).

By the way, in FIG. 7, the KK cross section, the LL cross section, the MM cross section, and the MM cross section in FIG. , FIG. 8, FIG. 9, and FIG. 10, and the damping force characteristics at each position are shown in FIGS.

Next, the operation of the control unit 4 that controls the driving of the pulse motor 3 will be described based on the flowcharts of FIGS. 15 and 16. This control is performed separately for each shock absorber SA.

First, in FIG. 15, in step 101, the vertical acceleration obtained from each vertical G sensor 1, 1, 1, 1 is processed by each filter circuit LPF 1, LPF 2, BPF 1, BPF 2, BPF 3 to make a bounce component. This is a step of performing a process of obtaining the signal v, the pitch component signal v ′, and the roll component signal v ″. Each component signal is given as a positive value when the sprung and sprung acceleration is in the upward direction, and It is given a negative value when downward.

In step 102, proportional constants α (α _f , α _r ), β (β _f , β _r ), γ (of the component signals v 1, v′v ″ are obtained according to the vehicle speed signal obtained from the vehicle speed sensor 5. This is the step of setting γ _f , γ _r ).

In step 103, the control signal V (V ₁ , V ₂ , V ₂ , V _{2) for} the position of each wheel is calculated based on the component signals v, v′v ″ and the proportional constants α, β, γ using the following formula 1. This is a step of calculating V ₃ , V ₄ ).

[0023]

[Equation 1] Note that α _f , β _f , and γ _f are the proportional constants of the front wheels α _r , β _r , and γ _r are the proportional constants of the rear wheels. Also, in each equation, they are joined by the first α _f and α _r . The part is the bounce rate, the part bounded by β _f and β _r is the pitch rate, and the part bounded by γ _f and γ _r is the roll rate.

Step 104 is a step for determining whether or not the control signal V is a positive value (upward direction). If YES (upward direction), the process proceeds to step 105, and if NO (downward direction), the step proceeds. Proceed to 120.

Step 105 is a step for determining whether or not the previous control signal V ₋₁ has a negative value. If YES (downward), the process proceeds to step 106, and if NO (upward), the step proceeds. Go to step 107. That is, in this step, it is determined whether or not the direction of the control signal is reversed from a negative value to a positive value.

Step 106 is a step of setting the initial value V _INIT of the basic threshold value V _MAX of the control signal V in the upward direction (extension side) and clearing the flag.

Step 107 is a step of determining whether or not the control signal V has become the initial value V _INIT or more. If YES (above), the process proceeds to step 108, and if NO (less than), the process proceeds to step 109.

Step 108 is a step of updating the value of the basic threshold value V _{MAX to} the value of the control signal V at that time.

Step 109 is a step of determining whether or not the updated value of the basic threshold value V _MAX is greater than or equal to the large input threshold value V _TH . If YES (above), the process proceeds to step 110 and NO. (Less than) proceeds to step 111.

Step 110 is a step of setting a flag.

Step 111 is a step of calculating the basic target position T _P1 of the extension side damping characteristic by the following equation.

T _P1 = V / V _MAX × P _MAX Note that V _MAX represents the updated basic threshold value.

Step 112 is a step of determining whether or not the flag is set. If YES (set), the process proceeds to step 113, and if NO (clear), the process proceeds to step 114.

Step 113 is a step of calculating a corrected target position T _P2 by multiplying the basic target position T _P1 by a constant (1.5) larger than 1.

Step 114 is a step of determining whether or not the target position T _P (T _P1 , T _P2 ) is _{equal to} or greater than the maximum damping position P _MAX . If YES, the process proceeds to step 115, and if NO, the process proceeds to step 116. .

Step 115 is a step of updating the target position T _P of the extension side damping characteristic to the maximum damping position P _MAX .

Step 116 is a step of driving the step motor 3 toward the target position T _P , and this ends one flow.

Next, proceeding to FIG. 16, step 120 is a step of determining whether or not the control signal V is 0, and if YES, then the process proceeds to step 121, and if NO, proceeds to step 122.

In step 121, the target positions T _P and T _−P are set to 0 (soft region SS), and this ends one flow.

Step 122 is a step of determining whether or not the previous control signal V ₋₁ has a positive value. If YES (upward), the process proceeds to step 123, and if NO (downward), the step proceeds. Proceed to step 124. That is, in this step, it is determined whether or not the direction of the control signal V is reversed from a positive value to a negative value.

Step 123 is a step of setting an initial value V _-INIT of the basic threshold value V _-MAX of the downward (pressure side) control signal V and clearing the flag.

Step 124 is a step of determining whether or not the control signal V has become equal to or less than the initial value V _−INIT . If YES (or less), the process proceeds to step 125, and if NO, the process proceeds to step ₁₂₆ .

Step 125 is a step of updating the value of the basic threshold value V _{−MAX to} the value of the control signal V at that time.

Step 126 is a step of determining whether or not the value of the updated basic threshold V _−MAX is less than or equal to the large input threshold V _{−T H} , and if YES (below), step 127 And proceeds to step 128 with NO.

Step 127 is a step of setting a flag.

Step 128 is a step of calculating the basic target position T _−P1 of the _compression side damping characteristic by the following equation.

T _−P1 = V / V _−MAX × P _−MAX where V _−MAX represents the updated basic threshold value.

Step 129 is a step of judging whether or not the flag is set, and if YES (set), the routine proceeds to step 130, and if NO (clear), the routine proceeds to step 131.

Step 130 is a step of calculating the corrected target position T _-P2 by multiplying the basic target position T _-P1 by a constant (1.5) larger than 1.

Step 131 is a step of determining whether or not the target position T _-P (T _-P1 , T _-P2 ) is less than or equal to the maximum damping position P _-MAX , and if YES, the process proceeds to step _132. , NO, the process proceeds to step 133.

Step 132 is a step of updating the target position T _−P of the _compression side damping characteristic to the maximum damping position P _−MAX .

In step 133, the step motor 3 is driven toward the target position T _−P , and this ends one flow.

Next, the operation of the embodiment apparatus will be described with reference to the time charts of FIGS. 17 and 18. First, the time chart of FIG. 17 will be described. From the top, the control signal V 1, the ON / OFF state of the large input control condition, and the change in the target position of the pulse motor 3 are shown.

First, when the control signal V is between the initial values V _INIT and V _−INIT of the basic threshold value, the control signal V is set to the basic threshold value in step 111 of FIG. 15 and step 128 of FIG. The proportional control of the damping characteristics is performed so that the damping characteristics of the shock absorber SA are maximized by the initial values V _INIT and V _-INIT of

Therefore, the sensitivity at the time of starting the damping force is increased, and the control response can be improved.

When the control signal V _exceeds the range of the initial values V _INIT and V _−INIT of the basic threshold values, the basic threshold values V _MAX and V are set in step 108 of FIG. 15 and step 125 of FIG. _{-Because MAX} is updated to the value of the control signal V at that time, each damping characteristic of the shock absorber SA is maintained in the maximum state until it reaches the peak value, and the control signal is changed from the peak value. Until the direction of V is reversed, the damping characteristic control in proportion to the control signal V which makes the value of the peak control signal V the maximum damping characteristic is performed in step 111 of FIG. 15 and step 128 of FIG. (Basic control) is performed.

Therefore, it is possible to improve the control responsiveness and eliminate a sudden change in the damping force to secure the riding comfort of the vehicle.

When the control signal V _exceeds the range of the large input threshold values V _TH and V _−TH , the steps 113 of FIG. 15 and the steps of FIG. 16 are performed until the direction of the control signal V is reversed. By 130, the damping characteristic control (correction control) is performed based on the corrected target positions T _P2 , T _-P2 obtained by multiplying the basic target positions T _P1 , T _-P1 by a predetermined constant (1.5) larger than 1.

When the correction control is performed in this manner, the time period for maintaining the maximum damping characteristic is extended as compared with the case where the basic control shown by the dotted line is performed, so the damping force is increased only by the hatched portion. It will be in the state of being.

Therefore, it is possible to enhance the damping performance of the vehicle at the time of a large input and enhance the steering stability.

Next, the time chart of FIG. 18 will be described. This time chart shows the case where the control signal V changes within the range of the large input threshold values V _TH and V _−TH .

When the control signal V changes as shown in this figure, when the control signal V is 0, the shock absorber SA is controlled to the soft region SS.

When the control signal V has a positive value, the extension side hard region HS is controlled to fix the compression side to the low damping characteristic.

When the control signal V has a negative value, the compression side hard region SH is controlled to fix the extension side to the low damping characteristic.

Further, in the time chart of FIG. 18, in the region a, the control signal V based on the sprung vertical velocity is reversed from a negative value (downward) to a positive value (upward). Since the relative speed is still a negative value (the stroke of the shock absorber SA is the pressure stroke side), at this time, the shock absorber SA moves to the extension side hard area HS based on the direction of the control signal V. Therefore, in this region, the pressure stroke side, which is the stroke of the shock absorber SA at that time, has a soft characteristic.

In the region b, the relative speed is from a negative value to a positive value (the stroke of the shock absorber SA is the extension side) until the control signal V based on the sprung vertical velocity is a positive value (upward). At this time, the shock absorber SA is controlled to the extension side hard area HS based on the direction of the control signal V, and the stroke of the shock absorber is also the extension stroke. In this region, the extension side, which is the stroke of the shock absorber SA at that time, has a hardware characteristic proportional to the value of the control signal V.

Further, in the region c, the control signal V based on the sprung vertical velocity is reversed from a positive value (upward) to a negative value (downward), but at this time, the relative velocity is still a positive value. (The stroke of the shock absorber SA is on the extension side). Therefore, at this time, the shock absorber SA is controlled to the compression side hard area SH based on the direction of the control signal V. Then, the extension side, which is the stroke of the shock absorber SA at that time, has soft characteristics.

In the region d, the control signal V based on the sprung vertical velocity is a negative value (downward), and the relative velocity is from a positive value to a negative value (the stroke of the shock absorber SA is on the pressure stroke side). At this time, the shock absorber SA is controlled to the compression side hard area SH based on the direction of the control signal V, and the stroke of the shock absorber is also the pressure stroke. Then, the pressure stroke side, which is the stroke of the shock absorber SA at that time, has a hardware characteristic proportional to the value of the control signal V.

As described above, in this embodiment, when the sprung vertical speed and the relative speed between the sprung part and the unsprung part have the same sign (area b, area d), the shock absorber SA is operated at that time. This is the same as the damping characteristic control based on the skyhook theory, in which the stroke side is controlled to the hard characteristic, and when the opposite sign (area a, area c) is controlled to the soft side on the stroke side of the shock absorber SA at that time. Is controlled without detecting the relative speed between the sprung part and the unsprung part. Further, in this embodiment, when the region a is changed to the region b and the region c is changed to the region d, the attenuation characteristics are switched without driving the pulse motor 3.

As described above, in this embodiment, the effects listed below can be obtained. By performing the correction control only at the time of a large input, it is possible to improve the control responsiveness by the basic control at the time of a small input while ensuring the riding comfort of the vehicle, and at the same time, perform the correction control for a large road surface input. It is possible to provide a vehicle suspension system that can obtain sufficient vibration damping properties and improve steering stability.

Since a sufficient control force can be generated not only for bounce but also for roll and pitch, it is possible to provide a vehicle suspension system that is excellent in riding comfort and steering stability.

As compared with the conventional damping characteristic control based on the Skyhook theory, the switching frequency of the damping characteristic is reduced, so that the control response can be improved and the durability of the pulse motor 3 can be improved. it can.

Since different constants α, β, and γ are used to obtain the bounce rate, the pitch rate, and the roll rate, the sprung resonance frequency, the pitch resonance frequency, and the roll resonance frequency are different in the vehicle. However, each rate can be accurately detected based on the sprung vertical velocity.

Next, other examples will be described, but in describing these examples, only differences from the first example will be described. The same reference numerals as those used in the first embodiment denote the same objects.

Second Embodiment In the second embodiment, a part of the control unit 4 is different from that of the first embodiment, and when calculating the control signal V, the arithmetic expression shown in the following formula 2 is used.

[0076]

[Equation 2] That is, in the second embodiment, the bounce rate is independently obtained based on the sprung vertical velocity of each wheel, and the control in which the bounce component is emphasized can be performed.

Although the embodiment has been described above, the specific configuration is not limited to this embodiment, and even if there is a design change or the like within the scope not departing from the gist of the invention, the invention is included in the invention. .

For example, in the embodiment, the expansion side has a variable damping characteristic and the compression side has a low damping characteristic fixed to the expansion side hard area, and the compression side has a variable damping characteristic and the expansion side has a compression side hard area fixed to the low damping characteristic, Although a shock absorber having three regions, a soft region having low damping characteristics on both the expansion side and the compression side, is used, a shock absorber having a structure in which the damping characteristics on the expansion side and the compression side change simultaneously can be used.

[0079]

[Effect of device]

 As described above, the vehicle suspension system of the present invention is based on the basic rule that the control signal reverses direction when the control signal based on the sprung vertical velocity is less than the predetermined large input threshold value. Until the threshold value is reached, the damping characteristic control is performed in proportion to the control signal so that the maximum damping characteristic is obtained at the basic threshold value, and when the threshold value is exceeded, the control signal is controlled until the peak value is reached. Value is updated to the basic threshold value, and the damping characteristic control proportional to the control signal with the peak value control signal value as the maximum damping characteristic is performed from the peak value until the direction of the control signal reverses. A control unit having a basic control unit to perform, and when the control signal exceeds a large input threshold value provided in the control unit, the damping characteristic control by the basic control unit is performed until the direction of the control signal is reversed thereafter. Given greater than 1 to result With a configuration that includes a correction control unit that performs damping characteristic control based on a value that is multiplied by a number, the control operation of the basic control unit improves the control response for small road surface inputs and The ride comfort can be ensured, and for a large road surface input, the control operation of the correction control unit can provide sufficient vibration damping properties and improve the steering stability. .

In the vehicle suspension system according to a second aspect of the present invention, each shock absorber has an expansion side hard region in which the expansion side has a variable damping characteristic and the compression side has a low damping characteristic, and the compression side has a variable damping characteristic and the expansion side has a low damping characteristic. It is formed in a structure having three regions, a compression side hard region where the characteristics are fixed and a soft region where both the expansion side and compression side have low damping characteristics, and the damping characteristic control means is shocked when the control signal has a positive value. By controlling the absorber in the expansion side hard area, controlling the shock absorber in the compression side hard area when the control signal has a negative value, and controlling the shock absorber in the soft area when the control signal is 0. Since the damping characteristic control based on the skyhook theory can be performed without using the relative velocity detection means, switching of the damping characteristic can be performed as compared with the conventional damping characteristic control based on the skyhook theory. As a result, the control frequency can be improved, and the durability of the damping characteristic switching actuator can be improved.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a claim showing a vehicle suspension device of the present invention.

FIG. 2 is a structural explanatory view showing a vehicle suspension device of the first embodiment of the present invention.

FIG. 3 is a system block diagram showing a vehicle suspension system of the first embodiment.

FIG. 4 is a sectional view showing a shock absorber applied to the device of the first embodiment.

FIG. 5 is an enlarged cross-sectional view showing a main part of the shock absorber.

FIG. 6 is a damping force characteristic diagram corresponding to the piston speed of the shock absorber.

FIG. 7 is a characteristic diagram of damping characteristics corresponding to a step position of the pulse motor of the shock absorber.

FIG. 8 is a K of FIG. 5 showing a main part of the shock absorber.
FIG.

FIG. 9 is an L of FIG. 5 showing a main part of the shock absorber.
It is a -L cross section and a MM cross section.

FIG. 10 is a sectional view taken along line NN of FIG. 5, showing a main part of the shock absorber.

FIG. 11 is a damping force characteristic diagram of the shock absorber when the extension side is hard.

FIG. 12 is a damping force characteristic diagram of the shock absorber in a soft state on the extension side and the compression side.

FIG. 13 is a damping force characteristic diagram of the shock absorber in a compression side hard state.

FIG. 14 is a block diagram showing a main part of a control unit of the first embodiment.

FIG. 15 is a flowchart showing the control operation of the control unit of the first embodiment device.

FIG. 16 is a flowchart showing the control operation of the control unit of the first embodiment device.

FIG. 17 is a time chart showing the operation of the first embodiment device.

FIG. 18 is a time chart showing the operation of the first embodiment device.

[Explanation of symbols]

 a damping characteristic changing means b shock absorber c sprung vertical velocity detecting means d basic control section e control section f correction control section

Claims (2)

[Scope of utility model registration request] 1. A shock absorber which is interposed between a vehicle body side and each wheel side and whose damping characteristic can be changed by a damping characteristic changing means, a sprung vertical speed detecting means for detecting a sprung vertical speed, and a sprung vertical direction. When the control signal based on speed is less than the predetermined large input threshold value, the value of the basic threshold value is the maximum damping characteristic between the time when the control signal reverses direction and reaches the predetermined basic threshold value. Attenuation characteristic control is performed in proportion to the control signal so that the control signal value is updated to the basic threshold value until the peak value is reached when the threshold value is exceeded, and the direction of the control signal from the peak value is changed. Until the reverse direction, the control means having a basic control part for performing the damping characteristic control in proportion to the control signal having the peak value of the control signal as the maximum damping characteristic; Input threshold After that, until the direction of the control signal is reversed, the correction control unit performs the damping characteristic control based on the value obtained by multiplying the damping characteristic control result by the basic control unit by a predetermined constant greater than 1. A vehicle suspension device characterized by being provided. 2. The shock absorber includes an expansion side hard area in which the expansion side is variable in damping characteristics and the compression side is fixed in low damping characteristics, and a compression side hard area in which the compression side is variable in damping characteristics and expansion side is fixed in low damping characteristics is expanded. It is formed in a structure having three regions, a soft region having a low damping characteristic on both the side and the compression side, and the damping characteristic control means controls the shock absorber in the extension side hard region when the control signal has a positive value. The shock absorber is controlled in the pressure side hard region when the signal has a negative value, and the shock absorber is controlled in the soft region when the control signal is 0.
The vehicle suspension system described.