JP5985290B2 - Electric pump control device - Google Patents

Description

  The present invention relates to a control device for an electric pump that is driven by a motor and supplies hydraulic oil to a drive system of a vehicle.

  In this type of electric pump, Patent Document 1 discloses a technique for limiting the motor current based on the integrated value of the phase current after the start of driving in order to suppress a failure due to the temperature rise associated with the motor driving. .

JP 2002-238293 A

  However, in Patent Document 1, when the drive (stop) of the pump (motor) is repeated, the phase current is accumulated from 0 each time the drive starts even after the drive circuit temperature rises due to repeated heat generation during the drive. For this reason, the current limit amount set according to the phase current integrated value is reduced. For this reason, in the case of a failure in which the pump friction is large (hereinafter referred to as friction failure), there is a possibility that the current increases excessively more than the necessary amount and the amount of heat generated in the drive circuit increases, leading to failure.

  The present invention has been made by paying attention to such a conventional problem. By appropriately setting the current limit value of the motor, a failure suppression function is enhanced, and an electric pump control device capable of suppressing power consumption is provided. The purpose is to provide.

For this reason, this invention is a control apparatus of the electric pump which is driven by a motor and supplies hydraulic oil, Comprising: The following means are comprised.
A. Based on the oil temperature rise characteristic according to the continuous drive time of the electric pump and the required current of the motor at each oil temperature, the current limit value stored as a map with the characteristics of the motor current limit value for each continuous drive time Storage means B. Pump drive time integration means for calculating the integral value by sequentially integrating the drive time of the electric pump. Using the integral value of the drive time of the electric pump calculated by the pump drive time integration means, a current limit value is set from the map of the current limit value characteristics for each continuous drive time stored in the current limit value storage means. , Motor current limiting means for limiting the motor current with the current limit value

  According to the present invention, even when pump driving and stopping are repeated, it is possible to set an appropriate current limit value commensurate with the oil temperature that rises as the integral value of the driving time increases, and heat generation of the driving circuit The amount is limited, so that failure can be suppressed and wasteful power consumption can be suppressed.

The figure which shows the driving force transmission system of the vehicle provided with the electric pump which concerns on embodiment. The control block diagram of the said electric pump. The figure which shows the raise characteristic in the low temperature state of the hydraulic oil temperature with respect to the continuous drive time of an electric pump. The diagram which shows the characteristic of the required electric current of a motor with respect to the drive time integral value of an electric pump, and a current limiting value. The time chart which shows the drive state and drive time integral value of the electric pump in 1st Embodiment. 5 is a flowchart of control for setting a current limit value in the first embodiment. The time chart which shows the drive state and drive time integral value of the electric pump in 2nd Embodiment. 9 is a flowchart of control for setting a current limit value in the second embodiment. The time chart which shows the drive state, drive time integral value, and actual oil temperature of the electric pump in 3rd Embodiment. 9 is a flowchart of control for setting a current limit value in the third embodiment. The flowchart of the control in 5th Embodiment.

An embodiment in which the present invention is applied to an electric pump that supplies hydraulic oil (working fluid) for lubrication and cooling to a continuously variable transmission of a vehicle will be described below.
In FIG. 1, a continuously variable transmission 4 is connected to an engine (internal combustion engine) 1 via a torque converter 2 and a forward / reverse switching mechanism 3 that is a starting clutch mechanism.

  The forward / reverse switching mechanism 3 includes, for example, a planetary gear mechanism including a ring gear, a pinion and a pinion carrier connected to the engine output shaft, a sun gear connected to the transmission input shaft, and a reverse brake that fixes the transmission case to the pinion carrier. And a forward clutch that couples the transmission input shaft and the pinion carrier, and switches between forward and reverse of the vehicle. Switching between the reverse brake and the forward clutch is performed by switching hydraulic engagement using hydraulic oil common to the continuously variable transmission 4.

  The continuously variable transmission 4 includes a primary pulley 41 and a secondary pulley 42, and a V belt 43 hung between these pulleys. The primary pulley 41 rotates via the V belt 43 through the secondary pulley 42. The rotation of the secondary pulley 42 is transmitted to the drive wheels to drive the vehicle.

  During the transmission of the driving force, the movable conical plate of the primary pulley 41 and the movable conical plate of the secondary pulley 42 are moved in the axial direction to change the contact position radius with the V-belt 43, whereby the primary pulley 41 and the secondary pulley 42 The rotation ratio, that is, the gear ratio can be changed.

The transmission mechanism 20 including the forward / reverse switching mechanism 3 and the continuously variable transmission 4 is controlled as follows.
The CVT control unit 5 as an external device calculates a shift control signal based on various signals of the vehicle, and the pressure adjusting mechanism 6 to which the shift control signal is input shifts the discharge pressure from the mechanical pump 7 driven by the engine. This is done by adjusting the pressure for each part of the mechanism 20 and supplying it.

  On the other hand, an electric pump 8 is disposed in a passage that bypasses the mechanical pump 7. The electric pump 8 is driven by a control signal from a CVT control unit (CVTCU) 5 as an external device in order to alleviate a fastening shock at the start of the vehicle or to lubricate and cool each lubricated part. .

  Note that a check valve 9 for preventing the backflow of the hydraulic oil at the normal time may be provided in the oil passage at the outlet of the electric pump 8 as necessary. Further, as shown by the dotted line in the figure, in order to limit the discharge pressure from the electric pump 8 to a predetermined pressure or lower, a relief valve 10 that opens at the predetermined pressure or lower may be provided.

FIG. 2 is a control block diagram of the electric pump.
The CVTCU 5 inputs detection signals (vehicle speed, brake, accelerator, shift position, engine speed, battery voltage, etc.) from various sensors of the vehicle and the temperature of the hydraulic oil (oil temperature) measured by the oil temperature sensor 11. The target rotational speed of the electric pump 8 is calculated according to the vehicle operating state detected based on these signals, and the target rotational speed is output to the electric pump 8 as a command value.

The electric pump 8 includes a pump main body 81, a motor 82 that drives the pump main body 81, and a drive circuit 83 that drives the motor 81.
The drive circuit 83 detects the motor rotation speed (pump rotation speed) and transmits it to the CVTCU 5, and drives the motor 82 so that the actual rotation speed converges to the target rotation speed based on the command value from the CVTCU 5.

  Further, although oil temperature information is not transmitted from the CVTCU 5 to the drive circuit 83, the drive circuit 83 is based on the drive time of the electric pump 8 as described below, and the heat resistance of the drive circuit 83 and the motor 82 (drive circuit, etc.) is as follows. The motor current limit value (current limit value) for satisfying the above is calculated.

  FIG. 3 shows a case where the oil temperature at the start of pump driving is the lower limit value in the pump driving region and the oil temperature that rises as the continuous driving time after driving increases at the lower limit increasing rate, that is, every hour. The characteristics when the oil temperature is the lower limit are shown. In the pump operating region, as the oil temperature increases, the viscosity of the operating oil decreases and the drive resistance of the electric pump 8 decreases, so that the required current decreases.

  The oil temperature lower limit value for each time obtained from FIG. 3 with respect to the continuous drive time and the required current value are obtained according to the oil temperature lower limit value. Since this required current value becomes larger as the oil temperature is lower as described above, it is obtained as the upper limit required current value. FIG. 4 shows a current limit value for satisfying the heat resistance of the motor 82, the drive circuit 83, etc. by suppressing the energization of the current exceeding the upper limit required current value while allowing the upper limit required current value for each time. This characteristic is set as shown, and this characteristic is stored in the memory.

  In this embodiment, the integral value of the motor driving time is used as the time on the horizontal axis in FIG. 4 (continuous driving time). As shown in FIG. 5, when the electric pump 8 is intermittently driven according to the operation state, the integral value is not reset by stop, and driving time T1, T2, T3,. Are sequentially integrated. In other words, the oil temperature once raised by driving the pump during driving is not likely to change greatly in a short time. Therefore, the oil temperature is obtained by sequentially integrating the driving time during driving while keeping the integrated value during this time constant. It is a value according to the rise of.

FIG. 6 shows a flow of control for setting a current limit value in the first embodiment.
In step S1, it is determined whether or not the pump is being driven. If it is determined that the pump is being driven, in step S2, the drive times T1, T2, T3,.

Based on the integral value of the drive time calculated in step S3, the current limit value is set from the characteristic map shown in FIG.
By limiting the motor current with the current limit value set based on the drive time integrated value in this way, even when the pump drive and stop are repeated, the oil temperature that increases as the drive time integrated value increases is met. The required current of the motor 82 is decreased, and the current limit value is decreased and set.

  As a result, the increase in the motor current at the time of friction failure in which the drive resistance of the electric pump 8 increases can be limited by the current limit value, the heat resistance of the drive circuit 83 and the like can be secured, and the pump failure can be suppressed, which is useless. Power consumption can also be suppressed.

  Since an appropriate current limit value can be set using an integral value of the drive time that can be calculated using a timer built in the drive circuit 83, for example, an oil temperature detection value for setting the current limit value is set. When it is applied to a system that does not require transmission from the CVTCU 5 to the drive circuit 83 and has a limited amount of transmission information from the CVTCU 5 to the drive circuit 83, such as PWM communication, or a system that does not want to increase the amount of transmission information even in CAN communication, etc. Also effective.

  As described above, normally, a decrease in oil temperature that has been raised while the electric pump 8 is being driven can be ignored, but in particular, in a hybrid vehicle or the like, the engine is non-rotating and the ignition switch is turned on for a long time. In situations where the oil is left in the ON state, the oil temperature may be lowered. In this way, when the oil temperature is lowered, the pump drive is resumed, and when the motor current is limited by the current limit value set according to the oil temperature increased based on the drive time integrated value before the stop, the reduced oil It becomes difficult to secure the necessary current commensurate with the temperature.

The second embodiment corresponds to the above point, and corrects the drive time integral value at the end of the immediately preceding drive while the drive is stopped in accordance with the elapsed time.
However, the heat dissipation characteristics of the drive circuit 83 and the like are such that excessive heat generation of the drive circuit 83 after re-driving is suppressed and heat resistance can be secured even if the current limit value is raised by decreasing the integral value during stoppage. Set the integral value reduction characteristics in consideration. For example, as shown by the solid line in FIG. 7B, the integral value reduction rate is set to reduce the time that is 1/3 of the drive OFF time.

  Further, since the oil temperature (and the drive circuit) is lowered due to the primary filter characteristic in the state of being left, the integral value is reduced by the integral value reduction rate of the characteristic indicated by the one-dot chain line in FIG. Also good.

FIG. 8 shows a flow of control for setting a current limit value in the second embodiment.
When it is determined in step S1 that the electric pump 8 is stopped, the process proceeds to step S4, and the integral value is reduced at the integral value reduction rate set as described above from the drive time integral value calculated in step S2.

When the driving is resumed after the driving is stopped, the integration calculation at step S2 is resumed with the integral value at the end of the stopping as an initial value.
According to the second embodiment, the current limit value is raised within a range in which the heat resistance of the drive circuit 83 and the like can be ensured according to the increase in the required current accompanying the decrease in the oil temperature estimated during the drive stop, so that the stop particularly Even when the time is prolonged, the necessary current can be secured and the pump control can be maintained well.

In this embodiment, when the continuous stop time after the drive stop has passed a predetermined time during which the oil temperature is sufficiently lowered, the drive time integrated value may be set to zero.
On the other hand, the drive time integrated value during driving is obtained such that a current limit value that can ensure the upper limit required current value corresponding to the characteristics when the oil temperature per hour is the lower limit value as described in FIG. Although calculated, when the actual oil temperature is higher than the lower limit temperature, the required current decreases, and the current limit value can be reduced accordingly. Further, even when the drive of the electric pump 8 is stopped, the hydraulic oil may be heated by the frictional heat of a rotating mechanism such as a mechanical pump 7 that is driven by an engine after the clutch is connected, and the oil temperature may rise.

  The third embodiment corresponds to the above-described points. When the drive is stopped, the oil temperature information is input from the CVTCU 5 to the drive circuit 83 instead of the drive command value, and the drive circuit 83 is based on the oil temperature information. Based on this, the current limit value is set more appropriately.

FIG. 9 shows a control flow for setting a current limit value in the third embodiment.
If it is determined in step S1 that the driving of the pump is stopped, the integral value is reduced from the drive time integral value by the integral value reduction rate set as described above in step S4, and then the process proceeds to step S5.

  In step S5, based on the oil temperature information supplied from the CVTCU 5 to the drive circuit 83, the lower limit value B of the drive time integrated value corresponding to the actual oil temperature is calculated. This lower limit value B can be calculated as the lower limit value B of the drive time integrated value in FIG.

In step S6, it is determined whether the drive time integrated value (= A) reduced in step S4 is smaller than the lower limit value B of the drive time integrated value calculated in step S5.
When it is determined in step S6 that A ≧ B, the integral value A calculated in step S4 is selected, and the heat resistance of the drive circuit 83 and the like is ensured.

On the other hand, when it is determined in step S6 that A <B, in step S7, the lower limit value B is selected as the driving time integral value.
FIG. 10 shows the oil temperature behavior in the third embodiment at the time of the lower oil temperature state behavior (oil temperature behavior X) shown in FIG. 3 and the behavior at the higher oil temperature state (oil temperature behavior Y). ) And a change in the integral value of the driving time. In the case of the oil temperature behavior Y, the oil temperature for the same elapsed time from the start of driving the electric pump 8 is higher than the oil temperature behavior X, and the drive time integrated value corresponding to the oil temperature is set to be large.

  According to the third embodiment, based on the latest information on the oil temperature that is input while the drive is stopped, the drive time integrated value can ensure the heat resistance of the drive circuit 83 and the like for each of the second and subsequent drive starts, and It is raised and updated to the lower limit B or more according to the actual oil temperature. As a result, the current limit value can be reduced to a necessary limit, and it is possible to suppress the flow of useless current when a friction failure occurs as much as possible.

In addition, at the time of a friction failure, a reduction in the motor rotation speed appears remarkably due to the current limitation at the lower limit B, so that the failure can be detected at an early stage.
In the case of PWM communication, the frequency at the time of driving and stopping the pump is made different so that driving / stopping is discriminated according to the frequency, and at each frequency, the indicated rotational speed (or indicated current) corresponding to the oil temperature is driven If the detected oil temperature information is supplied as a duty value when the information is stopped, it can be dealt with by one PWM communication without increasing the amount of transmission information. Even in the case of CAN communication, if it is not desired to increase the amount of transmission information, it is effective to switch from the instruction current to the transmission of the oil temperature information when the drive is stopped.

  Further, the reduction calculation in step S4 in the third embodiment is not performed, and the drive time integrated value A ′ at the end of driving of the electric pump 8 calculated in step S2 and the lower limit corresponding to the actual oil temperature in step S5. It is good also as an embodiment (4th embodiment) of composition which chooses the larger one with value B.

  Normally, the lower limit value B set corresponding to the actual oil temperature is compared with the driving time integrated value A set according to the lower limit oil temperature state and the driving time integrated value A ′ reduced accordingly. Therefore, the lower limit value B may be set as the drive time integral value (initial value) at the time of resuming the drive, but the oil is obtained by selecting the larger drive time integral value compared to A or A ′. Even when the lower limit B is lowered due to an abnormality in the temperature sensor 11 or the like, A or A ′ is selected as the drive time integral value, so that the heat resistance of the drive circuit 83 and the like can be ensured.

  Further, in the first to fourth embodiments described above, the driving time during driving of the electric pump 8 may be integrated by performing a correction that gives higher weighting as the motor current during driving is larger. Since the temperature of the drive circuit 83 and the like rises according to the motor current, the estimated temperature of the drive circuit 83 and the like can be brought close to the actual temperature by the above correction, so that the current limit value is set smaller according to the estimated temperature. Power consumption can be reduced. When the current sensor is not provided or when the motor current detection value cannot be input to the drive circuit side, the correction may be performed based on the duty value of the target rotation speed according to the oil temperature.

  When integrating the drive time of the electric pump 8 as in the embodiment described above, the integrated value of the drive time is reset after turning off the ignition switch, but it is turned on in a short time after turning off the ignition switch. In the case of starting, if the integral value is reset immediately after the OFF operation, the current limit value is too large to substantially limit the current.

  FIG. 11 shows the flow of control in the fifth embodiment corresponding to the above points, in which the CVTCU 5 is provided with a self-shut function or applied in advance to a CVTCU 5 having a self-shut function.

In step S11, it is determined whether the engine ignition switch has been turned off.
When it is determined that the ignition switch has been turned off, the process proceeds to step S12 to determine whether a predetermined time has elapsed. The predetermined time is set to a time during which the temperature of the drive circuit 83 or the like can be lowered to a temperature at which the drive time integrated value is to be reset.

When it is determined that the predetermined time has elapsed, the process proceeds to step S13, and the CVTCU 5 is subjected to a self-shut process, whereby the drive time integrated value is reset.
According to the fourth embodiment, when the ignition switch is turned ON in a situation where the oil temperature cannot be sufficiently lowered in a short time after the ignition switch is turned OFF, the self-shut process does not operate.

  As a result, the storage of the drive time integral value before the ON operation is maintained, and the integration is restarted with the stored integral value as an initial value. Therefore, the integral value commensurate with the oil temperature can be calculated, and the current can be calculated. It can be limited appropriately.

  The above embodiments have been applied to the control device for the electric pump for generating the transmission hydraulic pressure, but the same applies to the control device for the electric pump used for cooling the driving motor of the hybrid vehicle or the inverter. The same effect can be obtained.

  DESCRIPTION OF SYMBOLS 1 ... Engine, 5 ... CVT control unit, 8 ... Electric pump, 11 ... Oil temperature sensor, 20 ... Transmission mechanism, 82 ... Motor, 83 ... Drive circuit

Claims (3)

A control device for an electric pump driven by a motor to supply hydraulic oil,
Based on the oil temperature rise characteristic according to the continuous drive time of the electric pump and the required current of the motor at each oil temperature, the current limit stored as a map with the characteristics of the motor current limit value for each continuous drive time Value storage means;
Pump driving time integrating means for sequentially integrating the driving time of the electric pump to calculate an integral value ;
Using the integral value of the drive time of the electric pump calculated by the pump drive time integration means, the current limit value is set from the map of the current limit value characteristics for each continuous drive time stored in the current limit value storage means Motor current limiting means for limiting the motor current with the current limit value ;
The control apparatus of the electric pump characterized by including.   The pump drive time integration means subtracts a correction value for each time set according to a continuous stop time of the electric pump from the drive time integrated value while the drive of the electric pump is stopped. Item 2. A control device for an electric pump according to Item 1.   The pump drive time integration means inputs hydraulic oil temperature information from the outside while the pump is stopped, and calculates the lower limit limit value of the drive time integrated value based on the latest hydraulic oil temperature information when the pump drive is resumed. 3. The drive time integral value at the time of resuming pump drive is set as the lower limit value when the drive time integral value while the pump is stopped is smaller than the lower limit value. The control apparatus of the electric pump of description.