JP2843789B2 - Swash plate type variable displacement hydraulic motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swash plate type variable displacement hydraulic motor, and more particularly, to omitting a tilt piston for driving a swash plate to increase a tilt angle and changing the tilt angle steplessly. Related to what is configured.

[0002]

2. Description of the Related Art As shown in FIG. 5, a swash plate type variable displacement hydraulic motor 100 generally includes a housing 101, a cylinder block 102, a plurality of pistons 104 inserted into a plurality of cylinder holes 103 thereof, a swash plate 105, A swash plate support mechanism 107 for supporting the motor shaft 106 and the swash plate 105 to be tilted about a tilt center line orthogonal to the axis of the motor shaft 106, and for driving the swash plate 105 to a tilt angle increasing side. Tilting cylinder 108, tilting cylinder 109 for driving the swash plate to the tilting angle decreasing side, tilting cylinder 1
08, 109 through hydraulic pressure, tilt angle regulator 110, tilt angle of swash plate 105 tilt angle regulator 1
Feedback lever 111 for feeding back to 10
The tilt angle regulator 110 receives a command pressure from the outside and drives the tilt cylinders 108 and 109 so that the tilt angle corresponds to the command pressure. FIG. 6 is a hydraulic circuit diagram for the hydraulic motor 100, which is substantially the same as the hydraulic circuit of FIG.

[0003]

As described above, in the conventional swash plate type variable displacement hydraulic motor, since two tilting cylinders are provided, the hydraulic motor becomes large, the number of parts increases, and the manufacturing cost increases. There is a problem that it becomes expensive. In the swash plate type hydraulic motor described in Japanese Patent Publication No. 7-99137, the tilting center of the swash plate is eccentric from the axis of the motor shaft toward the top dead center, and a tilting cylinder for increasing the tilting angle is provided. Although omitted, the configuration is such that the rotational speed of the hydraulic motor is switched between two stages of low speed and high speed. However, this swash plate type hydraulic motor is not of a variable displacement type capable of switching the tilt angle steplessly, but is of various types. It is not a versatile one applicable to the application.

An object of the present invention is to omit a tilting cylinder for increasing the tilting angle of a swash plate type variable displacement hydraulic motor, to make the overall configuration compact, reduce the number of parts, and reduce the manufacturing cost. .

[0005]

According to a first aspect of the present invention, there is provided a swash plate type variable displacement hydraulic motor having a housing, a cylinder block, a plurality of pistons respectively inserted into a plurality of cylinder holes thereof, a swash plate, and a motor shaft. In a plate-type variable displacement hydraulic motor, a swash plate support mechanism for tiltably supporting a swash plate in a housing in such a manner that a center of the swash plate tilts from a motor shaft axis to a cylinder hole of a cylinder block. A swash plate support mechanism set at a position eccentric to the top dead center where it enters, a tilt cylinder including a tilt piston that drives the swash plate toward a tilt angle decreasing side, and a tilt commanded by an external command pressure A tilt angle regulator that drives the tilt cylinder to make an angle, and a feed lever that is linked to the swash plate and feeds back the tilt angle of the swash plate to the tilt angle regulator. Tsu is obtained by a click mechanism.

In the swash plate support mechanism, the tilt center of the swash plate is set at a position eccentric from the axis of the motor shaft toward the top dead center. Since the plate is biased toward the tilt angle increasing side, the tilt angle of the swash plate is automatically switched to the maximum when the tilt piston is retracted to the maximum, and when the tilt piston is advanced, the swash plate is The tilt angle decreases. The tilt angle regulator drives the tilt cylinder so as to obtain a tilt angle commanded from the outside by a command pressure, and the feedback mechanism operates the tilt angle of the swash plate via a feedback lever interlocked with the swash plate. Is fed back to the tilt angle regulator. Therefore, the tilt angle of the swash plate becomes the tilt angle commanded by an external command pressure in cooperation with the tilt angle regulator, the tilt cylinder, and the feedback mechanism, and the tilt angle can be switched steplessly. Can be. In addition, since the tilt cylinder for increasing the tilt angle can be omitted, the number of parts can be reduced, the manufacturing cost can be reduced, and the swash plate type variable displacement hydraulic motor can be downsized.

According to a second aspect of the present invention, in the swash plate type variable displacement hydraulic motor according to the first aspect of the present invention, the eccentricity of the tilt center increases the tilt angle of the swash plate by hydraulic pressure acting on the swash plate from a plurality of pistons. It is configured to be biased to the side. Although this configuration is substantially included in claim 1, this claim 2 is provided to clarify this configuration. This effect is
As described in claim 1.

According to a third aspect of the present invention, in the swash plate type variable displacement hydraulic motor, the tilting cylinder is
The tilt piston pushes the end of the swash plate extending from the top dead center to the side opposite to the bottom dead center. With this configuration, the tilt cylinder can be arranged near the feedback mechanism including the feedback lever and the tilt angle regulator, and an oil path to the tilt cylinder can be easily formed.

According to a fourth aspect of the present invention, in the swash plate type variable displacement hydraulic motor according to the second aspect of the present invention, the tilting cylinder comprises:
The tilt piston pushes the end of the swash plate extending from the bottom dead center to the side opposite to the top dead center. With this configuration, the tilting cylinder can be disposed on the side opposite to the slope of the swash plate. Therefore, the distance from the tilting center to the tilting cylinder is reduced, so that the stroke of the tilting cylinder is reduced and the size is reduced. Can be.

According to a fifth aspect of the present invention, in the swash plate type variable displacement hydraulic motor according to the third or fourth aspect, the tilt angle regulator includes a spool-sleeve valve mechanism, and a feedback lever is connected to the sleeve. Things. In this case, an external command pressure is applied to the spool of the spool / sleeve valve mechanism to switch the oil path, to adjust the hydraulic pressure of the tilting cylinder to increase or decrease, and to use a feedback lever via the sleeve of the spool / sleeve valve mechanism. Switch.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a swash plate type variable displacement hydraulic motor 1 is slidably and oil-tightly slidable in a housing 2, a cylinder block 7 housed in a housing chamber 6 thereof, and a plurality of piston holes 8 of the cylinder block 7. A plurality of pistons 9 mounted on the swash plate, a swash plate 10, a swash plate support mechanism 12 that supports the swash plate 10 so as to be tiltable around a tilt center line 11, a cylinder block 7 and a swash plate 10. The inserted motor shaft 14, the wet multi-plate brake 13 and its brake spring 13 a, a tilt cylinder 16 including a tilt piston 15, a tilt angle regulator 17, and a swash plate 10.
And a feedback mechanism 19 (see FIG. 2) including a feedback lever 18 connected to the control unit.

The housing 2 comprises a housing main body 3, an intermediate block 4 bolted to the housing main body 3, and an end plate 5 bolted to the housing main body 3, and the motor shaft 14
At 0,21, it is rotatably supported by the housing 2.
Incidentally, the spring force of the brake spring 13a is changed to the wet type multi-plate brake 1
When the hydraulic motor 1 stops, the piston member 13b that transmits the brake force to the multi-plate brake 13 applies the spring force of the brake spring 13a to the multi-plate brake 13 when the hydraulic pressure inside the brake member 13b decreases when the hydraulic motor 1 stops. It is made to brake. The cylinder block 7 is spline-coupled to the motor shaft 12, the left end surface of the cylinder block 7 is in sliding contact with a low-friction receiving member 22, and a plurality of shoes 23, each of which is spherically connected to the tip of the plurality of pistons 9, Retainer 2
4 and these shoes 23 are attached to the slope 25 of the swash plate 10.
Are in sliding contact with the low friction annular plate 26.

An arc-shaped hydraulic supply port 27 and a discharge port 28 are formed on the front and rear sides of the intermediate block 4 in FIG. 1 respectively. The hydraulic pressure is supplied through a passage 29, and the hydraulic pressure is discharged from almost the remaining half of the cylinder holes 8 to a discharge port 28 through an oil passage 30. Is a swash plate 1
It is driven to rotate by the action of 0 and rotates integrally with the motor shaft 12.

The swash plate support mechanism 12 supports the swash plate 10 so as to be tiltable around a tilt center line 11 perpendicular to the plane of FIG. 1. The swash plate support mechanism 12 includes a motor shaft 14.
A pair of hemispherical portions 31 protruding from the inner surface of the end wall portion 3a of the housing body 3 on both front and rear sides, and a pair of hemispherical recesses 32 into which the pair of hemispherical portions 31 are rotatably fitted. It has a pair of hemispherical recesses 32 formed on the right end surface of the plate 10, and each hemispherical portion 31 is fixed by screwing its leg 31a to the end wall 3a. Since the hemispherical portion 31 does not have a specific direction, it is advantageous for fixing by screwing. The tilt center line 11 passing through the center of the pair of hemispherical portions 31 is located at the top dead center (the piston 9
The swash plate is always eccentric to the swash plate 10 from the plurality of pistons 9 during the operation of the hydraulic motor 1 because the swash plate 10 is eccentric to a predetermined distance (about the radius of the motor shaft 12) toward the side where the swash plate 10 protrudes to the maximum. A moment acts to urge the motor 10 toward the tilt angle increasing side.

The tilting cylinder 16 is provided at the upper end of the housing 2 and extends from the position of the top dead center of the swash plate 10 to the side opposite to the bottom dead center by the tilting piston 15 of the tilting cylinder 16. The tip of the tilting piston 15 is spherically engaged with a spherical seat member 33 fixed to the extension 10a. The cylinder 16 is supplied with control pressure from a tilt angle regulator 17. In the state of the maximum tilt angle in which the tilt piston 15 retreats to the maximum, the contact surface 10b of the lower end portion of the swash plate 10 contacts the inner surface of the end wall 3a, and the tilt piston 15 advances a predetermined stroke to tilt. When the turning angle is minimized, the upper contact surface 10c of the swash plate 10 contacts the inner surface of the end wall 3a.

The tilt angle regulator 17 drives the tilt cylinder 16 so that the tilt angle is instructed by a command pressure supplied from the outside. As shown in FIGS. The tilt angle regulator 17 has a spool-sleeve valve mechanism 34. The lower end of the feedback lever 18 of the feedback mechanism 19 that feeds back the tilt angle of the swash plate 10 to the tilt angle regulator 17 is rotatably engaged with the pin 35 of the extension 10 a of the swash plate 10. Is connected to the sleeve 34a of the spool-sleeve valve mechanism 34.

The hydraulic circuit of the hydraulic motor 1 is shown in FIG.
The hydraulic motor 1 rotates forward when hydraulic pressure is supplied from the port Am, and reversely rotates when hydraulic pressure is supplied from the port Bm, and the drain oil is discharged from the drain port Dr. A moment M due to the eccentricity acts on the swash plate 10.

The servo pressure Ps supplied from the outside and the hydraulic pressure Pb of the port Bm are supplied to the shuttle valve 36, and the higher hydraulic pressure Ps or Pb is selected to become the control pressure Pc, and this control pressure Pc is used as the direction switching valve 37. Is supplied to the tilting cylinder 16 via the spool / sleeve valve mechanism 34 and the throttle valve 38, and the spool 3 of the spool / sleeve valve mechanism 34
The command pressure Pi obtained by adjusting the command pressure oil pressure Pio supplied from the outside by the electromagnetic pressure reducing valve 39 is supplied to the cylinder 34c that drives the 4b. The electromagnetic pressure reducing valve 39 is electrically driven by a drive signal from the control device and generates a command pressure Pi. The hydraulic pressure at the port Am is introduced into the large piston chamber 37a of the direction switching valve 37, and the control pressure Pc is introduced into the small piston chamber 37b.

When the spool / sleeve valve mechanism 34 is in the state shown in FIG. 2, the tilt piston 15 retreats to the maximum, and the tilt angle becomes maximum (maximum torque) by the moment M. When the command pressure Pi increases, the spool 34b moves to the left to supply hydraulic pressure to the tilting cylinder 16, and the tilting piston 15 advances to reduce the tilting angle. The tilt angle of the swash plate 10 is adjusted via the feedback lever 18 to the sleeve 34a.
When the tilt angle becomes an angle corresponding to the command pressure Pi, the sleeve 34a is moved by the feedback lever 18, and the spool / sleeve valve mechanism 34 is switched to the block position. In this way, the cooperation of the tilt angle regulator 17, the feedback mechanism 19, and the tilt cylinder 16 controls the tilt angle so that the tilt angle corresponds to the command pressure Pi.

The operation of the hydraulic motor 1 described above will be described. The tilt center (tilt center line 11) of the swash plate 10 is eccentric from the axis of the motor shaft 14 toward the top dead center by a predetermined distance, and the hydraulic pressure acting on the swash plate 10 from the plurality of pistons 9 makes the swash plate 1
Since zero is biased to the tilt angle increasing side, the tilt angle increasing cylinder can be omitted, and the tilt cylinder 16 for driving the swash plate 10 to the tilt angle decreasing side can be provided. The number of parts can be reduced, manufacturing costs can be reduced, and the hydraulic motor 1 can be downsized. Further, since the tilt cylinder 16 is provided near the tilt angle regulator 17 and the feedback mechanism 19, the structure of the oil passage to the tilt cylinder 16 is simplified. Moreover, since the tilt angle can be changed steplessly in accordance with the command pressure via the tilt angle regulator 17 and the feedback mechanism 19, the rotation speed and torque of the variable displacement hydraulic motor 1 can be changed steplessly. Variable capacity function can be secured.

Next, a description will be given of a modified embodiment in which the above-described embodiment is partially modified. 1) As shown in FIG. 3, the tilting cylinder 16A drives an end 10d of the swash plate 10 extending from the position of the bottom dead center to the side opposite to the top dead center from the side opposite to the slope of the swash plate 10. The swash plate 10 is driven by the tilting piston 15A of the tilting cylinder 16A and the oscillating member 15a spherically connected to the tilting piston 15A provided on the end wall 3a of the housing body 3 so as to decrease the tilting angle. It is configured to do so. In this case, since the distance from the tilt center line 11 to the tilt cylinder 16A is reduced, the stroke of the tilt piston 15A is reduced,
The tilting cylinder 16A can be downsized. still,
Other configurations are almost the same as those of the above embodiment.

2] As shown in FIG. 4, the swash plate support mechanism 12
A, the swash plate 10 is provided on both front and rear sides of the motor shaft 14.
A pair of partial columnar portions 31A having a predetermined front-rear width centered on the tilting center line 11A is formed integrally with the right end surface portion of A, and a pair of partial columnar portions 31A are respectively formed on the end wall member 3A of the housing 2. A pair of partial cylindrical seats 32A that are rotatably engaged are formed. Since the tilt center line 11A is eccentric by a predetermined distance from the axis of the motor shaft 14 toward the top dead center,
Also in this structure, the swash plate 10A is
A moment acts to urge the swash plate 10A toward the tilt angle increasing side by the hydraulic pressure acting on the swash plate. The tilt piston 15B of the tilt cylinder 16B pushes the swash plate 10A to the tilt angle decreasing side via the swing member 15b at the tip.

3) The above embodiments and modifications are merely examples of the present invention, and the present invention can be applied to swash plate type variable displacement hydraulic motors of various structures without departing from the spirit of the present invention. Of course, for example, the swash plate support mechanism 1
2 instead of the hemispherical part 31 and the hemispherical concave part 32
A pair of semi-cylindrical bodies centered on one and a pair of semi-cylindrical recesses with which these semi-cylindrical bodies are rotatably engaged may be provided.

[0024]

According to the swash plate type variable displacement hydraulic motor of the first aspect, the tilt angle commanded by an external command pressure is obtained by cooperation of the tilt angle regulator, the tilt cylinder and the feedback mechanism. The swash plate support mechanism sets the tilt center of the swash plate at a position eccentric from the axis of the motor shaft to the top dead center side while ensuring a variable capacity function that switches the tilt angle of the swash plate steplessly. Since the swash plate is urged toward the tilt angle increasing side by hydraulic pressure acting on the swash plate from a plurality of pistons, the tilt cylinder for increasing the tilt angle can be omitted, so that the number of parts is reduced. Therefore, the manufacturing cost can be reduced, and the swash plate type variable displacement hydraulic motor can be downsized.

According to the swash plate type variable displacement hydraulic motor of the second aspect, the eccentricity of the tilting center urges the swash plate toward the tilt angle increasing side by the hydraulic pressure acting on the swash plate from the plurality of pistons. With such a configuration, the same effects as those described in claim 1 can be obtained.

According to the swash plate type variable displacement hydraulic motor of the third aspect, the same effect as that of the second aspect is obtained, but the tilting cylinder is moved from its top dead center position to its bottom dead center position by its tilting piston. Is configured to push the end of the swash plate extending to the opposite side, so that the tilting cylinder can be arranged near the feedback mechanism including the feedback lever and the tilting angle regulator, and the oil passage to the tilting cylinder is formed. Easy to form.

According to the swash plate type variable displacement hydraulic motor of the fourth aspect, the same effect as that of the second aspect is obtained, but the tilting cylinder is moved by its tilting piston from the position of the bottom dead center to the top dead center. The end of the swash plate that extends to the opposite side is pushed, so that the tilt cylinder can be placed on the opposite side of the swash plate slope, reducing the distance from the tilt center to the tilt cylinder. As a result, the stroke of the tilting cylinder can be reduced and the size can be reduced.

According to the swash plate type variable displacement hydraulic motor of the fifth aspect, the same effect as the third or fourth aspect is obtained, but the tilt angle regulator is provided with a spool-sleeve valve mechanism, and the feedback is provided to the sleeve. Since the lever is connected, an external command pressure is applied to the spool of the spool / sleeve valve mechanism to switch the oil path, increase / decrease the hydraulic pressure of the tilting cylinder, and use the feedback lever via the spool / sleeve valve mechanism sleeve. To switch the oil path.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a swash plate type variable displacement hydraulic motor according to an embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram of the hydraulic motor of FIG.

FIG. 3 is a longitudinal sectional view of a hydraulic motor according to a modified embodiment.

FIG. 4 is a longitudinal section of a hydraulic motor according to another modification.

FIG. 5 is a longitudinal sectional view of a main part of a swash plate type variable displacement hydraulic motor according to the related art.

6 is a hydraulic circuit diagram of the hydraulic motor of FIG.

[Explanation of symbols]

 Reference Signs List 1 swash plate type variable displacement hydraulic motor 2 housing 7 cylinder block 8 cylinder hole 9 piston 10, 10A swash plate 11, 11A tilting center line 12, 12A swash plate support mechanism 14 motor shaft 15, 15A, 15B tilting piston 16, 16A, 16B Tilt cylinder 17 Tilt angle regulator 18 Feedback lever 19 Feedback mechanism 34 Spool / sleeve valve mechanism 34a Sleeve

Claims (5)

(57) [Claims] 1. A swash plate type variable displacement hydraulic motor having a housing, a cylinder block, and a plurality of pistons, a swash plate, and a motor shaft respectively inserted into a plurality of cylinder holes thereof. A swash plate support mechanism for supporting the swash plate, wherein a tilting center of the swash plate is set at a position eccentric to a top dead center side where a piston enters a cylinder hole of a cylinder block as much as possible from an axis of a motor shaft. A tilting cylinder including a tilting piston that drives the swash plate to a tilting angle decreasing side, a tilting angle regulator that drives the tilting cylinder to have a tilting angle commanded by a command pressure from the outside, A feedback mechanism including a feedback lever that is interlocked with the swash plate and feeds back the tilt angle of the swash plate to the tilt angle regulator. The amount hydraulic motor. 2. The swash plate is urged toward a tilt angle increasing side by hydraulic pressure acting on the swash plate from a plurality of pistons due to the eccentricity of the tilt center. The swash plate type variable displacement hydraulic motor as described in the above. 3. The tilt cylinder according to claim 1, wherein the tilt piston is configured to push an end of a swash plate extending from a position of a top dead center to a side opposite to a bottom dead center. 3. The swash plate type variable displacement hydraulic motor according to 2. 4. The tilting cylinder, wherein the tilting piston is configured to push an end of a swash plate extending from a position of a bottom dead center to a side opposite to a top dead center. 3. The swash plate type variable displacement hydraulic motor according to 2. 5. The swash plate type variable displacement hydraulic motor according to claim 3, wherein the tilt angle regulator includes a spool / sleeve valve mechanism, and a feedback lever is connected to the sleeve. .