JP2001115943A - Electric hydraulic servomotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small electric hydraulic servomotor. SOLUTION: In the electric hydraulic servomotor 100 for rotating an output shaft 61 according to a rotating speed difference between a rotary shaft 41 and an output shaft 61, a longitudinal groove 71c extendedly disposed in the axial direction is formed on a spool 71, a first helical gear 52 is inserted into the longitudinal-groove 71c, and is engaged and held with the spool 71 so as to set the axial direction of the spool 71 and the axial direction of the first helical gear 52 in parallel with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrohydraulic servomotor used for a hydraulic excavator, a crane, an asphalt finisher, a machine tool, and the like (hereinafter, simply referred to as an external device).

[0002]

2. Description of the Related Art In a conventional electro-hydraulic servomotor, as shown in FIGS.
And is rotatably supported by the casing 1. A valve plate 9 is fixed to the inner wall of the casing 1, and a cylinder block 7 is fixed to a periphery of the output shaft 2. A plurality of pressure chambers 7a are formed in the cylinder block 7, and the pressure chambers 7a
The piston 8 is accommodated in each of the
Is reciprocated in the axial direction by the hydraulic pressure of the working oil introduced into the pressure chamber 7a.

[0003] A swash plate 6 inclined at a predetermined angle facing the valve plate 9 is fixed to the inner wall of the casing 1 on the tip side of the output shaft 2, and the tip of the piston 8 presses and slides the swash plate 6. At the same time, the cylinder block 7 slides on the valve plate 9 and the output shaft 2
And the cylinder block 7 rotate together.

[0004] The casing 1 is provided with a spool valve 11 which moves in the axial direction, and a screw member 12 and a gear 13 are fixed to the front and rear ends of the spool valve 11, respectively. The casing 1 includes a pulse motor 14.
The rotary shaft 15 of the pulse motor 14 is rotatably supported by the casing 1. The torque of the rotating shaft 15 is transmitted to the spool valve 11 via the gears 16 and 13, and the torque of the output shaft 2 is transmitted to the screw members 10 and 12.
Through the spool valve 11.
The spool valve 11 rotates the oil drain passage 1a and the oil supply passage 1b.
And the communication passages 1c and 1d.

[0005] In a conventional electro-hydraulic servo motor,
The output shaft 2, the spool valve 11, and the pulse motor 14 are arranged on the same axis.

[0006]

However, in the above-described conventional electrohydraulic servomotor, since the output shaft 2, the spool valve 11, and the pulse motor 14 are arranged on the same axis, the overall length becomes long, and other machines are not used. There was a problem that it did not fit well.

Accordingly, an object of the present invention is to provide a small-sized electro-hydraulic servomotor.

[0008]

According to a first aspect of the present invention, there is provided an electro-hydraulic servomotor according to the first aspect of the present invention, wherein an electric motor for rotating a rotating shaft in response to an input signal and an output based on the pressure of hydraulic oil. Hydraulic drive means for rotating the shaft, a first shaft connected to the rotating shaft, a cylindrical second shaft screwed to the first shaft and having external teeth formed on the outer periphery, and external teeth formed on the outer periphery. Forming and meshing with the external teeth of the second shaft, and controlling the supply amount and discharge amount of hydraulic oil to the hydraulic drive means by moving the third shaft connected to the output shaft and the spool in the axial direction. An electro-hydraulic servomotor that rotates the output shaft in accordance with a difference in the number of rotations between the rotation shaft and the output shaft by the spool being interlocked with the second shaft. Form a long groove extending in the axial direction, There is inserted into the elongated groove, the axial direction of the second axis to the axial direction of the spool, characterized in that it is engaged with and held by the spool to be parallel.

The electro-hydraulic servo motor according to a second aspect of the present invention provides an electric motor for rotating a rotating shaft in response to an input signal, hydraulic drive means for rotating an output shaft by the pressure of hydraulic oil, and the rotating shaft. A first shaft connected to the first shaft, a cylindrical second shaft screwed to the first shaft and having external teeth formed on the outer periphery, and external teeth and teeth of the second shaft formed with external teeth formed on the outer periphery. And
A third shaft connected to the output shaft, and a spool valve that moves a spool in an axial direction to control a supply amount and a discharge amount of hydraulic oil to the hydraulic drive unit, wherein the spool is the second shaft. In conjunction with, in an electro-hydraulic servomotor that rotates the output shaft according to the difference in the number of rotations between the rotation shaft and the output shaft, the second shaft engages with both ends of the second shaft, respectively. A pair of bearing means for supporting the, the spool forms an elongated groove extending in the axial direction,
The second shaft is inserted into the long groove, is engaged and held by the spool via the pair of bearing means such that the axial direction of the spool and the axial direction of the second shaft are parallel, A pair of bearing means move the spool in the axial direction when the second shaft moves in the axial direction, and prevent the spool from rotating around the shaft when the second shaft rotates about the shaft. It is characterized by the following.

According to the first or second aspect of the present invention, since the axes of the rotating shaft and the output shaft do not have to be on the same line, the size of the electrohydraulic servomotor can be reduced. In addition, since the second shaft is inserted and held in the long groove of the spool, the spool follows the second shaft with high response, and the electro-hydraulic servomotor can accurately control the spool. it can. Further, since the number of parts can be reduced, the size of the electrohydraulic servomotor can be reduced.

According to a third aspect of the present invention, the electro-hydraulic servo motor further comprises a spool rotation preventing means for preventing the spool from rotating around a shaft. According to the electro-hydraulic servomotor of the third aspect, even if the spool is prevented from rotating about the axis, the second shaft is not prevented from rotating about the axis. Therefore, when the spool is moved in the axial direction by the electric motor, the load on the electric motor is reduced, so that the electric motor can be downsized, and the electro-hydraulic servomotor can be downsized.

According to a fourth aspect of the present invention, in the electro-hydraulic servo motor, the long groove is formed at an axially intermediate portion of the spool. According to the electrohydraulic servomotor according to the fourth aspect, the total length of the spool can be reduced, so that the electrohydraulic servomotor can be downsized.

According to a fifth aspect of the present invention, in the electro-hydraulic servo motor, the extension of the axis of the rotating shaft and the extension of the axis of the output shaft are arranged so as to maintain a predetermined angle. Features. According to the electrohydraulic servomotor according to the fifth aspect, the total length of the electrohydraulic servomotor can be shortened, so that the electrohydraulic servomotor can be downsized.

[0014]

Preferred embodiments of the present invention will be described below with reference to the drawings.

First, the configuration of the electrohydraulic servomotor according to the present embodiment will be described.

1 to 4, the electrohydraulic servomotor 100 has a cup-shaped first casing 30 and a second casing 31 fastened and fixed to the first casing 30 by bolts 32. Also, the first casing 3
0 has a bolt hole 33 into which a bolt is screwed when the electro-hydraulic servomotor 100 is fastened and fixed to an external device (not shown). The second casing 31 has an oil supply passage 31a and a communication passage 31b. , A communication passage 31c and an oil discharge passage 31d.

A pulse motor 40 is mounted on the outer wall of the second casing 31 as a motor for rotating the rotating shaft 41 in response to an input signal. Pulse motor 4
A drive shaft 51 as a first shaft having a male screw 51a formed on the outer periphery is integrally connected to the 0 rotation shaft 41 in the rotation direction. In the present embodiment, the rotating shaft 41 and the driving shaft 51 are formed of one component, but in the present invention, the rotating shaft 41 and the driving shaft 51 may be formed of separate components. . Reference numeral 37 denotes a cap cover for preventing hydraulic oil from flowing out to the pulse motor main body 42.

The drive shaft 51 has a first helical gear 52 as a cylindrical second shaft having an internal thread 52a formed on the inner periphery and external teeth 52b formed on the outer periphery. 51a is connected by screwing into the female screw 52a of the first helical gear 52. The first helical gear 52 has a second helical gear 5 as a third shaft having external teeth 53a formed on the outer periphery.
3, when the external teeth 52b of the first helical gear 52 mesh with the external teeth 53a of the second helical gear 53, the axis of the first helical gear 52 and the second helical gear 53 Are connected so as to be orthogonal to each other.

One end of a second helical gear 53 is connected to one end of an output shaft 61 of a hydraulic motor 60 as hydraulic drive means, which will be described later, via a connecting member 54 so as to be integral in the rotational direction. The other end of the second helical gear 53 is
It is rotatably supported by a cap cover 34 attached to the casing 31. In the present embodiment,
Although the second helical gear 53 and the output shaft 61 are composed of separate parts, in the present invention, the second helical gear 5
The output shaft 3 and the output shaft 61 may be composed of one part.

The shapes of the male screw 51a, the female screw 52a, the external teeth 52b, and the external teeth 53a are different from each other when a difference occurs in the rotation speed between the drive shaft 51 and the second helical gear 53. It is determined that the first helical gear 52 moves in the axial direction while rotating about the axis according to the difference in the number of rotations from the second helical gear 53.

The hydraulic motor 60 is composed of a first casing 30 and a second casing 31 by a bearing 68 and a bearing 69.
And the output shaft 61 urged toward the other end by the urging force of the spring 67, and fixed to the side wall of the second casing 31 to form the communication passage 31 b and the communication passage 31.
The plurality of arc holes 62a respectively communicating with c are slidably engaged with the valve plate 62 formed at positions spaced at equal intervals in the circumferential direction by the biasing force of the spring 67,
A cylinder block in which a plurality of pressure chambers 63a, which are fixed to the peripheral portion of the output shaft 61 in the rotation direction integrally with the output shaft 61 and have an axis parallel to the axis of the output shaft 61, are formed at positions equidistantly spaced in the circumferential direction. 63 and a plurality of pistons 64 housed in the pressure chamber 63a of the cylinder block 63 so as to be slidable in the axial direction and having a substantially spherical tip 64a at the tip.
And a shoe member 65 with the tip end 64a of the piston 64 rollably engaged with the shoe member 65, the shoe member 65 slidably engaged with the slope member 66a inclined at a predetermined angle with respect to the output shaft 61.
Swash plate 6 fixed to the inner wall of the first casing 30
6 is comprised.

The output shaft 61 protruding outside the first casing 30 is connected to a drive unit of an external device (not shown) so that a rotational force is transmitted to the drive unit.

The spool valve 70 is provided with a spool 71
And a second casing 31.

The spool 71 is connected to the first helical gear 52 via a pair of bearings 55 and 56 as bearing means. Here, the spool 71 is connected to the second casing 31 via the key 35 as a spool rotation preventing unit.
Is slidably engaged with the cap cover 36 attached to the cover. Therefore, the spool 71 does not rotate around the shaft.

The bearings 55 and 56 are formed of thrust bushes.

A long groove 71c extending in the axial direction is formed on the outer peripheral portion of the intermediate portion of the spool 71 in the axial direction. The first helical gear 52 is inserted into the long groove 71c, and the axial direction of the spool 71 and the first helical gear 52
Are engaged with and held by the spool 71 so that the axial direction of the spool 71 is parallel to the axial direction. Here, the spool 71 is attached to the cap cover 3 attached to the second casing 31 via the key 35.
6 is slidably engaged. Therefore, the spool 71 does not rotate around the shaft.

Further, an annular groove 71a and an annular groove 71b are formed in the outer peripheral portion of the spool 71 to connect the oil supply passage 31a and the oil discharge passage 31d of the second casing 31 to the communication passage 31b or 31c, respectively.

Next, the operation of the electrohydraulic servomotor 100 will be described.

The electrohydraulic servomotor 100 has a rotating shaft 4
When there is a difference between the rotation speeds of the output shaft 61 and the output shaft 61, the rotation shaft 4
The output shaft 61 is rotated according to the difference between the rotation speeds of the output shaft 61 and the output shaft 61.

Hereinafter, when there is a difference between the rotation speeds of the rotating shaft 41 and the output shaft 61, the electrohydraulic servomotor 100 changes the output shaft 6 according to the difference between the rotating speeds of the rotating shaft 41 and the output shaft 61.
The operation of rotating 1 will be described.

Since the drive shaft 51 is integrally connected to the rotation shaft 41 in the rotation direction, the rotation speed of the rotation shaft 41 is
1 and the output shaft 61 has a second helical gear 5
3 is connected integrally via the connecting member 54 in the rotation direction, the rotation speed of the output shaft 61 is equal to the rotation speed of the second helical gear 53.

Therefore, when there is a difference between the rotation speeds of the rotation shaft 41 and the output shaft 61, the drive shaft 51 and the second helical gear 5
There is also a difference in the number of revolutions from 3.

When there is a difference in the number of rotations between the drive shaft 51 and the second helical gear 53, as described above, according to the difference in the number of rotations between the drive shaft 51 and the second helical gear 53, The first helical gear 52 moves in the axial direction while rotating about the axis.

When the first helical gear 52 moves in the axial direction while rotating about the shaft, the spool 71 is connected to the first helical gear 52 via the bearings 55 and 56, so that the spool 71 71 also moves in the axial direction in conjunction with the first helical gear 52. Spool 71 is the first helical gear 5
When it moves in the axial direction in conjunction with 2, an annular groove 71 a and an annular groove 71 b connecting the oil supply passage 31 a and the oil discharge passage 31 d of the second casing 31 to the communication passage 31 b or 31 c respectively are formed on the outer peripheral portion of the spool 71. The oil supply passage 31a, the communication passage 31b, the communication passage 31c, and the oil discharge passage 3
The flow rate of the hydraulic oil flowing through 1d changes.

Oil supply passage 31a, communication passage 31b, communication passage 31
When the flow rate of the working oil flowing through the oil passage 31d and the oil passage 31d changes, the communication passage 31b and the communication passage 31c are connected to the cylinder block 6 through a plurality of arc holes 62a formed in the valve plate 62.
Since the plurality of pressure chambers 63a communicate with the plurality of pressure chambers 63a, the flow rates of the hydraulic oil flowing into the plurality of pressure chambers 63a change. When the flow rate of the hydraulic oil flowing into each of the plurality of pressure chambers 63a changes, the piston 64 flows out into the plurality of pressure chambers 63a because the piston 64 is slidably housed in the pressure chamber 63a of the cylinder block 63. Slides in the axial direction according to the pressure of the operating oil. When the piston 64 slides in the axial direction, the distal end 6 of the piston 64
4a is rollingly engaged with the shoe member 65, and the shoe member 65 is slidably engaged with the slope 66a of the swash plate 66. Is pressed. When the piston 64 presses the slope 66 a of the swash plate 66 via the shoe member 65,
The cylinder block 63 rotates about the axis by the reaction force of the force of the piston 64 pressing the slope 66 a of the swash plate 66.

When the cylinder block 63 rotates about the axis, the communication passage 31b and the communication passage 31c communicate with each other through the plurality of arc holes 62a formed in the valve plate 62. Changes. Cylinder block 6 in which communication passage 31b and communication passage 31c communicate with each other through a plurality of arc holes 62a formed in valve plate 62
When the pressure chamber 63a formed in 3 changes, the flow rate of the hydraulic oil flowing out to each of the plurality of pressure chambers 63a changes.
When the flow rate of the hydraulic oil flowing into each of the plurality of pressure chambers 63a changes, as described above, the cylinder block 63 rotates around the shaft again.

Therefore, the oil supply passage 31a and the communication passage 31
b, when the flow rate of the working oil flowing through the communication passage 31c and the oil discharge passage 31d changes, the cylinder block 63
1a, the communication path 31b, the communication path 31c, and the rotation in the rotation direction and the rotation speed according to the flow rate of the working oil flowing through the oil discharge path 31d around the shaft.

The cylinder block 63 includes the oil supply passage 31a,
When the cylinder block 63 is rotated around the shaft in a rotation direction and a rotation speed corresponding to the flow rate of the working oil flowing through the communication passage 31b, the communication passage 31c, and the oil discharge passage 31d, the cylinder block 63 Since the output shaft 61 is fixed integrally in the rotation direction, the output shaft 61 is also centered on the shaft in the rotation direction and the rotation speed according to the flow rate of the working oil flowing through the oil supply passage 31a, the communication passage 31b, the communication passage 31c, and the oil discharge passage 31d. Rotate.

Here, the drive shaft 51 and the second helical gear 53
When there is a difference in the number of rotations, the direction in which the first helical gear 52 moves in the axial direction while rotating about the axis is the direction of the male screw 51a, the female screw 52a, the external teeth 53a, and the external teeth 52b. It can be determined by the shape. That is, when a difference occurs in the rotation speed between the drive shaft 51 and the second helical gear 53 due to the shapes of the male screw 51a, the female screw 52a, the external teeth 53a and the external teeth 52b, the drive shaft 51 and the second helical gear 53 Helical gear 53
The rotation direction and the rotation speed at which the output shaft 61 rotates can be determined according to the difference between the rotation speed and the rotation speed.

Therefore, the male screw 51a and the female screw 52
a, when the shapes of the external teeth 53a and the external teeth 52b are determined, when a difference occurs in the rotation speed between the drive shaft 51 and the second helical gear 53, that is, when the rotation shaft 41 and the output shaft 61 When a difference occurs in the rotation speed, the output shaft 61 can be rotated so that the difference in rotation speed between the rotation shaft 41 and the output shaft 61 is reduced.

As described above, when there is a difference between the rotation speeds of the rotation shaft 41 and the output shaft 61, the electrohydraulic servomotor 100 responds to the difference between the rotation speeds of the rotation shaft 41 and the output shaft 61. The output shaft 61 is rotated.

The key 35 prevents the spool 71 from rotating around the shaft. When the spool 71 rotates around the shaft and collides with the second helical gear 53, the spool 71 rotates. Alternatively, the second helical gear 53 is prevented from being damaged.

In the present embodiment, the helical gear is used for the second shaft and the third shaft. However, in the present invention, the helical gear need not be the helical gear. For example, a predetermined speed ratio can be set between the second shaft and the third shaft by using another transmission gear, a worm screw, a worm wheel, or the like. When a predetermined speed ratio is set between the second shaft and the third shaft, the rotation speed of the output shaft 61 is reduced by the second shaft and the third shaft. Can be smaller than the rotation speed of Therefore, the capacity of the pulse motor 40 can be reduced, and the size of the electrohydraulic servomotor 100 can be reduced.

In the present embodiment, the bearing 55 and the bearing 56 are constituted by thrust bushes.
In the present invention, when the first helical gear 52 moves in the axial direction, the spool 71 is moved in the axial direction, and when the first helical gear 52 rotates about the shaft, the spool 71 moves about the shaft. The thrust bush is not limited to the thrust bush, and any other member may be used as long as the member prevents rotation.

In this embodiment, since the axis of the first helical gear 52 and the axis of the second helical gear 53 are connected to be orthogonal to each other, the axis of the rotary shaft 41 and the output Although the axes of the shafts 61 are also connected so as to be orthogonal to each other, in the present invention, the extension of the axis of the rotation shaft 41 and the extension of the axis of the output shaft 61 are maintained at another predetermined angle. May be arranged.

[0046]

According to the invention described in claim 1 or 2,
Since the axes of the rotating shaft and the output shaft do not need to be on the same line, the size of the electrohydraulic servomotor can be reduced. In addition, since the second shaft is inserted and held in the long groove of the spool, the spool follows the second shaft with high response, and the electro-hydraulic servomotor can accurately control the spool. it can. Further, since the number of parts can be reduced, the size of the electrohydraulic servomotor can be reduced.

According to the third aspect of the invention, even if the spool is prevented from rotating about the shaft, the second shaft is not prevented from rotating about the shaft. . Therefore, when the spool is moved in the axial direction by the electric motor, the load on the electric motor is reduced, so that the electric motor can be downsized, and the electro-hydraulic servomotor can be downsized.

According to the fourth aspect of the present invention, since the total length of the spool can be shortened, the size of the electrohydraulic servomotor can be reduced.

According to the fifth aspect of the present invention, the total length of the electrohydraulic servomotor can be reduced, so that the size of the electrohydraulic servomotor can be reduced.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an electrohydraulic servomotor according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line BB of FIG.

FIG. 3 is a schematic configuration diagram of the electrohydraulic servomotor shown in FIG.

FIG. 4 is a perspective view of a main part of the electrohydraulic servomotor shown in FIG.

FIG. 5 is a front view around the electric motor shown in FIG. 1;

FIG. 6 is a side sectional view of a conventional electrohydraulic servomotor.

FIG. 7 is a sectional view taken along the line AA of FIG. 6;

[Explanation of symbols]

 41 Rotary shaft 40 Pulse motor (motor) 61 Output shaft 60 Hydraulic motor 51 Drive shaft (first shaft) 52b External gear 52 First helical gear (second shaft) 53a External gear 53 Second helical gear (second motor) Three spools) 71 Spool 70 Spool valve 71c Long groove 100 Electro-hydraulic servomotor 55, 56 Bearing (pair of bearing means) 35 Key (spool rotation prevention means)

Claims (5)

[Claims] An electric motor for rotating a rotating shaft in response to an input signal; hydraulic drive means for rotating an output shaft by the pressure of hydraulic oil; a first shaft connected to the rotating shaft; A cylindrical second shaft screwed to the shaft and having external teeth formed on the outer periphery; and a third shaft formed with external teeth on the outer periphery and meshed with the external teeth of the second shaft, and connected to the output shaft. A shaft, and a spool valve configured to move a spool in an axial direction to control a supply amount and a discharge amount of hydraulic oil to the hydraulic drive unit. An electro-hydraulic servomotor that rotates the output shaft in accordance with the difference between the number of rotations of the output shaft and the output shaft, wherein the spool forms a long groove extending in the axial direction, and the second shaft is inserted into the long groove. The axial direction of the spool and the axial direction of the second shaft Electro-hydraulic servomotor, characterized in that it is engaged with and held in said spool such that row. 2. An electric motor for rotating a rotating shaft in accordance with an input signal, hydraulic drive means for rotating an output shaft by the pressure of hydraulic oil, a first shaft connected to the rotating shaft, A cylindrical second shaft screwed to the shaft and having external teeth formed on the outer periphery; and a third shaft formed with external teeth on the outer periphery and meshed with the external teeth of the second shaft, and connected to the output shaft. A shaft, and a spool valve configured to move a spool in an axial direction to control a supply amount and a discharge amount of hydraulic oil to the hydraulic drive unit. An electro-hydraulic servomotor that rotates the output shaft according to the difference between the number of rotations of the output shaft and the output shaft, comprising a pair of bearing means that respectively engage with both ends of the second shaft to support the second shaft. The spool forms an elongated groove extending in the axial direction; A shaft is inserted into the long groove, and is engaged and held by the spool via the pair of bearing means so that the axial direction of the spool and the axial direction of the second shaft are parallel to each other. The means moves the spool in the axial direction when the second shaft moves in the axial direction, and prevents the spool from rotating around the shaft when the second shaft rotates around the shaft. And electro-hydraulic servo motor. 3. The electro-hydraulic servo motor according to claim 1, further comprising a spool rotation preventing means for preventing rotation of the spool about a shaft. 4. The electro-hydraulic servo motor according to claim 1, wherein said elongated groove is formed at an axially intermediate portion of said spool. 5. An apparatus according to claim 1, wherein an extension of an axis of said rotary shaft and an extension of an axis of said output shaft are arranged so as to maintain a predetermined angle. An electro-hydraulic servomotor as described.