JP2000018171A - Capacity variable hydraulic pump or motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacity variable hydraulic pump or motor allowing easy assembling of capacity adjustment mechanism. SOLUTION: This pump or motor has a following structure. On a detection shaft 25a of a rotary potentio 25 which is capacity detection means, a detection gear 26 to be geared with a rack gear 23a is integrally mounted. With parts other than the rotary potentio 25 assembled, the detection shaft 25a of the rotary potentio 25 and the detection gear 26 are finally inserted to a detection shaft insertion hole 24c from outside. The detection gear 26 gears with the rack gear 23a of a control rod 23 and a pinion gear 22g that constitutes a gear row 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable displacement hydraulic pump or motor which can be used in various fluid equipment (hydraulic equipment) fields and the like, and more particularly to a pump having a capacity detecting means for detecting the capacity thereof.

[0002]

2. Description of the Related Art In a variable displacement hydraulic pump or motor, a displacement adjusting mechanism for changing the displacement comprises an electric motor and a control rod driven forward and backward by the electric motor. A direct-acting type using operation is known. This is, for example, as shown in FIG.
A control rod 123 having rack teeth 123a is connected to the output shaft 121a through a gear train 122 for reduction to convert the forward / reverse rotation of the electric motor 121 into a linearly moving forward / backward movement of the control rod 123. The capacity is changed by driving the spool type hydraulic servo mechanism directly by the forward / backward movement of the 123 or by using the forward / backward movement of the control rod 123 as a pilot.

On the other hand, since the demand for automatic control has been increasing in recent years, the capacity adjusting mechanism 120 is provided with a capacity detecting means, and a capacity signal detected from the capacity detecting means is fed back by a controller or the like, so that an electric motor is controlled. A motor having a function of driving the motor 121 and automatically controlling the motor to a required capacity has been developed. In the figure, the capacity detecting means is a rotary potentiometer 125, which extends a shaft 122h of a pinion gear 122g meshing with the control rod 123, and this pinion gear shaft 1
The detection shaft 125a of the rotary potentiometer 125 is directly connected to 22h. Specifically, the pinion gear shaft 1
The tip of 22h has a large diameter, the detection shaft 125a is fitted into a hole provided at the center thereof, and a screw hole Ba penetrated from the side into the large diameter of the pinion gear shaft 122g.
The pinion gear shaft 122h and the detection shaft 125a are connected to each other by screwing a set screw B therein. Thus, the value of the output signal of the rotary potentiometer 125 is
By detecting the rotation angle of 22g, the advance / retreat position of the control rod 123, that is, the capacity can be indirectly detected. The reason why the rotary potentiometer 125 is connected to the shaft 122h of the pinion gear 122g that directly meshes with the control rod 123 is to minimize the influence of backlash at the meshing portion and accurately measure the advance / retreat position of the control rod 123. is there.

[0004]

In this case, the hydraulic fluid leaked from the hydraulic pump / motor is guided to the rack teeth 123a and the gear train 122 for lubrication. It is necessary to seal so that the hydraulic fluid does not leak from the connection portion with the pinion gear shaft 122h to the rotary potentiometer 125 side.
For this purpose, a casing 124 for accommodating the gear train 122 is provided, and inside the detection shaft insertion hole 124 c penetrated through the outer wall of the casing 124, a pinion gear shaft 122 is provided.
h and the detection shaft 125a, and a seal member 127 that fits over the pinion gear shaft 122h is mounted on the inner periphery of the detection shaft insertion hole 124c.

Therefore, such a capacity adjusting mechanism 12
0, the gear train 122 is connected to the casing 12.
4, the detection shaft 125a must be connected to the pinion gear shaft 122h protruding into the detection shaft insertion hole 124c after the seal member 127 is mounted.
At this time, since it is necessary to screw the set screw B into the screw hole Ba, a set screw B penetrating from the outside to the inner periphery of the detection shaft insertion hole 124c and a set screw insertion hole 124d for tool insertion are provided. ing.

On the other hand, the resistance of the rotary potentiometer 125 generally changes linearly only in a predetermined rotation angle region. Therefore, the relative mounting angle when connecting the pinion gear shaft 122h and the detection shaft 125a so that the rotation angle region of the pinion gear shaft 122h associated with the forward and backward movement of the control rod 123 is within the predetermined rotation angle region of the rotary potentiometer 125. Must be adjusted.
Specifically, it is necessary to adjust the rotation angle of the rotary potentiometer 125 and connect the control rod 123 to a predetermined position (for example, a stroke end) so that the resistance value corresponds to the resistance value. On the other hand, a set screw insertion hole 124d and a screw hole B for screwing the set screw B
There is also a restriction that connection cannot be made unless a is matched with a.

Therefore, when the control rod 123 is set at a predetermined position (for example, at the stroke end), the control rod is adjusted so that the set screw insertion hole 124d and the screw hole Ba for screwing the set screw B are aligned. After assembling the plug 123 several times, the position is adjusted by trial and error, and then the rotation angle of the rotary potentiometer 125 is adjusted and connected. In addition, there is a problem that the screwing operation of the set screw B is extremely difficult, and the workability relating to the assembly is extremely poor.

That is, the gear train 122 is connected to the casing 12.
4 and a structure that is sealed by a pinion gear shaft 12a and a pinion gear shaft 12a.
With the idea of assembling the 2h with the 2h, it is necessary to perform the alignment of the control rod 123 and the angle adjustment of the rotary potentiometer 125 while assembling, resulting in more or less workability at the time of assembling.

The present invention focuses on such a problem, and by changing the idea of connecting the shafts to each other as described above, it is possible to assemble the components after adjusting each component individually. The main purpose is to improve the ease of assembly work.

[0010]

In order to achieve the above object, the present invention employs the following configuration. That is, the variable displacement hydraulic pump or motor according to the present invention is a variable displacement hydraulic pump or motor including a direct acting displacement adjusting mechanism capable of freely changing the displacement.
This capacity adjusting mechanism has a drive motor, a gear train interlocked with the rotation of the drive motor, and rack teeth meshing with gears constituting the gear train, and controls linearly moving forward and backward according to the forward / reverse rotation of the drive motor. A rod, a casing for accommodating the gear train and the control rod, and a capacity detecting means capable of indirectly detecting a capacity by detecting an advanced / retracted position of the control rod, using a forward / backward movement of the control rod. The capacity detecting means includes a rotatable detecting shaft, and a detecting gear integrally attached to the detecting shaft and meshing with the rack teeth, and a predetermined range. This is a rotary type that can detect the rotation angle of the detection shaft inside the motor. It was charged, characterized in that it constitutes the detection gear so as to mesh with the rack teeth of the control rod.

According to this structure, since there is no shaft-to-shaft connecting portion at the time of assembly, the control rod is set at a predetermined position in advance, the resistance value of the rotary potentiometer is set to a predetermined value, and then the rotary potentiometer is set. The final assembly can be done by simply mounting it on the casing. In other words, since final assembly can be performed after adjusting and setting individual parts, the disadvantage of having to adjust parts while assembling as in the past has been eliminated, and assembly work efficiency has been dramatically improved I do.

In addition, since the detection gear is simply added as compared with the prior art, the axial dimension of the entire apparatus does not increase. Further, since the detection gear directly meshes with the rack teeth, the influence of an error due to backlash in detecting the position of the control rod can be minimized.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 1, a variable displacement hydraulic pump or motor according to the present embodiment includes a pintle 2 which can be moved forward and backward in a casing 1 and the casing 1.
A torque ring 3 rotatably disposed therein, and an inner periphery 4a connected to the torque ring 3 so as to be eccentric to the torque ring 3 and rotatable synchronously with the torque ring 3 inside the torque ring 3. A cylinder block 4 fitted and held on the outer periphery of the cylinder block 2;
A plurality of pistons 5 arranged radially protruding and retractable at radially equidistant positions of the outer periphery and having a tip 5a constantly in sliding contact with the inner periphery 3a of the torque ring 3 and the pintle 2 are urged. And a servo mechanism 6 for eccentrically moving the cylinder block 4 with respect to the torque ring 3.

The servo mechanism 6 is provided with a cylinder bore 7a at one of the opposed end faces along the direction of movement of the pintle 2 (Y direction in FIG. 1), and a control piston 7b is fitted into the cylinder bore 7a. Forward actuator 7
And a retreating actuator 8 having a control bore 8a fitted in the cylinder bore 8a on the other end face, and the pintle 2
And a spool holding hole 9 having an axis parallel to the reciprocating direction, and a slidably fitted inside the spool holding hole 9 and having a high-pressure flow path L1 (L2 in some cases) on the outer periphery. And a capacity adjusting mechanism 2 for driving the spool 10 forward and backward by a control rod 23. The spool 10 has a high-pressure groove 10a and a low-pressure groove 10b opened to a low-pressure region.
0, one end is connected to the forward actuator 7 and the other end is the inner periphery of the spool holding hole 9 and communicates with the high-pressure groove 10a when the spool 10 is displaced in the forward direction. A first pressure introducing passage 12 opened to a portion that can communicate with the low-pressure groove 10b when the actuator is displaced, and an actuator 8 having one end retracted.
The other end is the inner periphery of the spool holding hole 9 and communicates with the high-pressure groove 10a when the spool 10 is displaced in the backward direction and communicates with the low-pressure groove 10b when displaced in the forward direction. And a second pressure introducing passage 13 opened at a position where the spool is to be obtained. First, the spool 10 is moved to a target position by the capacity adjusting mechanism 20, and the pintle 2 is moved to the target position following the spool. It can be driven by pressure.

The piston 5 and the cylinder block 4 project and retract due to the synchronous rotation of the cylinder block 4 and the torque ring 3 under eccentricity, so that the fluid flowing out of the piston 5 and the cylinder block 4 flows out. The input space S is expanded and contracted by a displacement volume corresponding to the eccentricity d,
Thereby, it is configured to be able to operate as a pump or a motor.

In this embodiment, however, FIG.
As shown in FIGS. 3 and 4, a capacity adjusting mechanism 20 is provided with a drive motor 21 and a gear train 2 linked to the rotation of the drive motor 21.
2, a casing 24 accommodating the gear train 22 therein,
A control rod 23 having rack teeth 23a meshing with the gear train 22 and moving forward and backward in response to forward and reverse rotations of the drive motor 21; and a position detecting means mounted outside the casing 24 and detecting the forward and backward positions of the control rod 23. A rotary potentiometer 25 is provided, and the spool 10 is advanced and retracted by the advance and retreat of the control rod 23 so that the capacity can be changed.

More specifically, the drive motor 21 is, for example, of an electric DC type, and can change the rotation speed freely by a signal from a controller (not shown). The gear train 22 functions as a speed reducer, and is mainly composed of a combination of two unit gears 22a and 22b in which a wheel gear and a pinion gear are fixed on the same shaft. Specifically, the output shaft 2 of the drive motor 21
1a, a wheel gear 22d of an intermediate unit gear 22a, which is one of the unit gears, is meshed with a pinion gear 22c attached to the tip of the intermediate unit gear 2a.
The pinion gear 22e of 2a is combined with the wheel gear 22f of the output unit gear 22b, which is the other unit gear, so as to mesh. Therefore, the rotation of the drive motor 21 is reduced and transmitted to the pinion gear 22g of the output unit gear 22b.

The casing 24 is composed of a gear train holding block 24a attached to the end face of the drive motor 21 on the output shaft side, and a cover block 24b attached to the end face of the gear train holding block 24a on the side opposite to the motor. . The gear train holding block 24a includes an output shaft 21a of the drive motor 21 and the two unit gears 22 described above.
a, 22b, and a pinion gear 22 of the output unit gear 22b from the end face on the side opposite to the motor.
g is projected. The cover block 24b is provided with a detection shaft insertion hole 24c for accommodating a detection shaft 25a and a detection gear 26 of a rotary potentiometer 25 to be described later from the outside, and a pinion holding portion for accommodating a pinion gear 22g of the output unit gear 22b. 24d, and a rod holding hole 24e for holding the control rod 23 so as to be able to protrude and retract along a direction orthogonal to the motor output shaft 21a.

The rotary potentiometer 25 has a main body 25c, a detection shaft 25a rotatably protruding from the main body 25b, and a rack shaft 23a which is integrally attached to a tip end of the main shaft 25a and meshes with the rack teeth 23a. And a detection shaft 26a.
Is a rotary type in which the resistance value changes according to the rotation angle. In the present embodiment, a one-rotation type in which the area where the resistance value linearly changes is set to a rotation angle area within 360 degrees of the detection axis 25a is adopted. Then detection axis 2
5a is provided in the second block 24b in the detection shaft insertion hole 24c.
, The potentiometer body 25c is mounted on the outer surface of the second block 24b. The detection gear 26 is fixed to the distal end of a connecting member 25b integrally attached to the detection shaft 25a using a set screw B. In the assembled state, the gear meshes with the rack teeth 23a, and meshes with the pinion gear 22g of the output unit gear 22b at a portion that is substantially 180 degrees out of phase with the meshing portion. That is, this detection gear 2
6 is on a power transmission path for transmitting power from the drive motor 21 to the control rod 26, and includes a gear train 22.
It also functions as a part of.

A method of assembling such a capacity adjusting mechanism 20 will be described below. First, the gear train holding block 24a and the drive motor 21 are assembled with the gear train 22 installed therein. Thereafter, the cover block 24b is mounted, and the control rod 23 is inserted into the rod holding hole 24e, for example, so that one stroke end is reached. Further, a seal member 27 is mounted in advance on the inner periphery of the detection shaft insertion hole 24c in the second block 24b. The seal member 27 can penetrate the detection gear 26 and slides on the outer periphery of the connecting member 25b.

On the other hand, the detection shaft 2 of the rotary potentiometer 25
The angle 5a is set so that its resistance value is a value corresponding to the stroke end of the control rod 23. Then, the detection shaft 25a and the detection gear 26 of the rotary potentiometer 25 are inserted into the detection shaft insertion hole 24c from outside, and the detection gear 26 meshes with the rack teeth 23a of the control rod 23 and the pinion gear 22g of the output unit gear 22b. Let it. The detection gear 26 can be meshed only by rotating in the normal and reverse directions within the range of one tooth. After that, the potentiometer body 25c is
4b with an unillustrated screw.

Therefore, according to the present embodiment, the control rod 23 is set at a predetermined position in advance, the resistance value of the rotary potentiometer 25 is set at a predetermined value, and the rotary potentiometer 25 is mounted on the cover block 24b. Final assembly can be performed. That is, since final assembly can be performed after setting individual components, the disadvantage that the components have to be adjusted while performing final assembly as in the related art is eliminated, and assembly work efficiency is significantly improved. .

In addition, the size in the axial direction does not increase, as compared with the conventional one, because the detection gear 26 is simply added. Further, since the detection gear 26 directly meshes with the rack teeth 23a, the control rod 2
In the position detection (3), the influence of an error due to backlash can be made as small as possible. The present invention is not limited to the above embodiment. Although the radial type has been described in the above embodiment, for example, the present volume adjusting mechanism can be applied to other variable displacement type hydraulic pumps or motors other than the present embodiment represented by a swash plate type, an oblique axis type and the like. It is. Further, the rack teeth of the control rod may be meshed with the pinion gear of the output unit gear as in the related art, and the detection gear may be arranged in parallel with the pinion gear of the output unit gear so as to mesh with the rack teeth.

Further, the configuration in which the pinion gear is mounted on the detection shaft is not limited to the above-described embodiment, and various methods are conceivable. In addition, the specific configuration of each unit is not limited to only the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0025]

As described above, according to the variable displacement hydraulic pump or motor of the present invention, the control rod is set at a predetermined position in advance, and the resistance value of the rotary potentiometer is set at a predetermined value. The final assembly can be performed by attaching the rotary potentiometer to the casing. That is, assembling can be performed after adjustment and setting of individual components, which eliminates the disadvantage that the components need to be adjusted while assembling, as in the past, and significantly improves assembly work efficiency. .

In addition, since the detection gear is simply added as compared with the conventional device, the axial size of the entire apparatus does not increase. Further, since the detection gear directly meshes with the rack teeth, the influence of an error due to backlash in detecting the position of the control rod can be minimized.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a variable displacement hydraulic pump or motor showing one embodiment of the present invention.

FIG. 2 is a vertical sectional view showing a capacity adjusting mechanism in the embodiment.

FIG. 3 is a sectional view taken along line AA in FIG. 4;

FIG. 4 is a sectional view taken along line BB in FIG. 4;

FIG. 5 is a longitudinal sectional view showing a capacity adjusting mechanism in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 20 ... Capacity adjustment mechanism 21 ... Drive motor 22 ... Gear train 23 ... Control rod 23a ... Rack teeth 24 ... Casing 25 ... Capacity detection means 25a ... Detection shaft 26 ... Detection gear

Claims (1)

[Claims] 1. A variable displacement hydraulic pump or motor having a direct acting displacement adjusting mechanism, wherein the displacement adjusting mechanism comprises a drive motor, a gear train interlocked with the rotation of the drive motor, and a gear train. By detecting a control rod having rack teeth meshing with gears constituting the gear and linearly moving forward and backward in response to forward and reverse rotations of the drive motor, a casing accommodating the gear train and the control rod, and detecting a forward and backward position of the control rod. A capacity detecting means capable of indirectly detecting the capacity, wherein the capacity can be freely adjusted by moving the control rod forward and backward, and the capacity detecting means includes a rotatable detection axis and a rotatable detection axis. A detection gear for integrally engaging with the rack teeth, the rotation type being capable of detecting a rotation angle of the detection shaft within a predetermined range; A variable capacity hydraulic pressure, wherein the capacity detection means is inserted from the outside of the casing in a state where the control rod is incorporated, and the detection gear can be meshed with the rack teeth of the control rod. Pump or motor.