JPH0868376A - Swash plate support structure of variable displacement type hydraulic motor - Google Patents

Abstract

PURPOSE: To provide a stable rotation speed by suppressing the generation of the backlash of the engagement of the swash plate of a variable displacement type hydraulic motor and to improve durability of the engagement part. CONSTITUTION: A swash plate 9 is supported at a body case 1 in such a manner to be inclinable centering around an axis Y and a pair of trunnion shafts 16 are protruded from the outer periphery of the swash plate 9. Each trunnion shaft 16 is pivotally supported in a pair of engaging recessed parts 17a formed in a bearing bracket 17 disposed deep in a drive chamber D.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swash plate support structure for a variable displacement hydraulic motor used for driving a crawler type traveling device.

[0002]

2. Description of the Related Art In a variable displacement hydraulic motor, a cylinder block having a large number of axial type plungers arranged therein is rotatably supported in a drive chamber formed in a main body case, and the inner chamber of the drive chamber is rotatably supported. In addition, the swash plate that receives the tip of each plunger is equipped and fixed, the swash plate is tiltably supported on the main body case, and the main body case is equipped with a hydraulic cylinder that pushes the swash plate from the side opposite to the plunger to tilt it. As the structure for supporting the swash plate, as shown in, for example, Japanese Patent Application Laid-Open No. 4-272482, the back side and the inner part of the swash plate are the inner bottom part of the drive chamber of the main body case. What is engaged with and supported by a pair of spherical bodies provided, or contrary to this structure,
As disclosed in Japanese Patent Publication No. 67, a pair of arc-shaped projections provided on the inner side of the back surface of the swash plate are engaged with and supported by a pair of concave grooves provided on the case body.

[0003]

However, according to the above-described conventional structure, the swash plate is engaged and supported so as to be tiltable in the inner portion of the swash plate, which is advantageous for downsizing the drive chamber. Since the interval at the engaging portion is narrow, the inclination of the engaging shaft core is eliminated, so that extremely high accuracy of parts is required. Further, the outer diameter of the swash plate is set to be substantially equal to the outer diameter of the plunger group arranged in the circumferential direction, and the pressing force of the plunger group is concentrated in the vicinity of the outer peripheral portion of the swash plate. Due to the pressing force on the outer part, rattling in the lateral direction is likely to occur, which not only makes the rotation speed unstable, but also may cause the engagement part to be worn early and is durable. There was room for improvement in terms of sex.

The present invention has been made paying attention to such a point, and it is possible to suppress the rattling of the engaging portion of the swash plate to supply a stable rotation speed and to improve the durability. An object of the present invention is to provide a swash plate support structure for a high variable displacement hydraulic motor.

[0005]

In order to achieve the above object, the characteristic structure of the first invention is that a pair of trunnion shafts are provided on the outer circumference of the swash plate so that each trunnion shaft is located inside the drive chamber. The bearing bracket is pivotally supported in a pair of engaging recesses provided in the bearing bracket disposed in the section. A characteristic configuration of the second invention is that in the first invention, the pair of engaging recesses are integrally formed via a bearing bracket. A characteristic configuration of the third invention is that in the first invention or the second invention, the bearing bracket is provided with each contact restricting surface in the low speed posture and the high speed posture of the swash plate.

[0006]

According to the characteristic construction of the first aspect of the invention, the pair of trunnion shafts projecting from the outer periphery of the swash plate are pivotally supported in the engaging recesses of the bearing bracket, so that the swash plate is acted between the pair of engaging portions. The pressing force of the Plunger County will be applied, and the rattling of the swash plate can be suppressed. The interval between the engaging portions becomes long, the deterioration of the position accuracy due to the assembly error can be reduced, and the mounting posture of the swash plate is stabilized. Directly look at the engaging recess of the bearing bracket located in the inner bottom of the drive chamber and the engaging part consisting of a pair of trunnion shafts protruding from the swash plate at the time of manufacturing and assembling work of the swash plate after disassembly and maintenance. You can

According to the characterizing feature of the second invention, since the engaging recesses for pivotally supporting the pair of trunnion shafts are integrally formed via the bearing bracket, compared with the case where the engaging recesses are provided separately. At the time of assembling work, there is no displacement of the shaft center formed by the pair of engaging portions, and the posture of the swash plate is stable. Further, since the common bearing bracket is used for mounting the engagement concave portion to the main body case, the number of fixing means can be reduced.

According to the third aspect of the invention, the bearing bracket integrally formed with the pair of engaging recesses is provided with the contact restricting surfaces in the low speed posture and the high speed posture of the swash plate. As compared with the case where the concave portion and the contact control surface are provided separately, an assembly error does not occur. In other words, by providing the swash plate contact control surface on the bearing bracket itself that holds the swash plate in place, assembly work can be performed while maintaining the initial settings at the manufacturing stage, so the trunnion shaft is pivotally supported. It was not necessary to finely adjust the inclination angle of the swash plate with respect to the engaging portion.

[0009]

As described above, according to the first aspect of the present invention, by suppressing the rattling of the swash plate, the durability of the engaging concave portion of the bearing bracket and the engaging portion composed of a pair of trunnion shafts protruding from the swash plate. Has improved. A stable output rotation speed was obtained by reducing the deterioration of the position accuracy and stabilizing the mounting posture of the swash plate. The engaging part can be seen directly at the time of manufacturing and assembling work of the swash plate after disassembly and maintenance, and the workability is improved to improve maintainability.

According to the second aspect of the invention, since the posture of the swash plate can be stabilized with extremely high positional accuracy while having a simple structure, a more stable output rotation speed can be obtained. or,
By using a common bearing bracket, the engagement recess can be attached to the inner bottom of the drive chamber in the main body case.
Make the work easy.

According to the third aspect of the present invention, by providing the bearing bracket with the contact restricting surface of the swash plate, the number of parts is reduced to reduce the cost, and the swash plate has a simple structure with extremely high positional accuracy. Since it was possible to stabilize the low-speed posture and the high-speed posture, the desired low-speed rotation and high-speed rotation could be easily obtained after manufacturing and assembling work.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 7 shows a drive unit when the variable displacement hydraulic motor M of the present invention is used as a drive motor capable of switching between high and low speeds of a crawler traveling device in a construction machine such as a backhoe. A cross section of the hydraulic motor M is shown. The main body case 1 of the hydraulic motor M is connected and fixed to the outer surface of a frame (track frame) 2 of the machine body via a flange 1a, and includes a drive chamber D that opens toward the frame 2 side, and the opening of the drive chamber D The parts are closed by two hydraulic blocks 3 and 4 connected in series. A rotary shaft 5 is horizontally supported at the center of the drive chamber D, and a cylinder block 7 having a large number of axial plungers 6 arranged in the circumferential direction is attached to the rotary shaft 5. Further, a swash plate 9 for receiving the rotary head 6a of the plunger 6 group via the thrust plate 8 is fixedly installed inside the drive chamber D.

At the front part of the main body case 1, a rotating case 10 is provided.
Is rotatably fitted and mounted via a bearing 11, and a drive sprocket 13 engaging with a crawler belt 12 is connected to the rotating case 10. Also, body case 1
An output shaft 14 concentrically connected to the rotary shaft 5 is provided in the center of the front surface of the rotary shaft 5, and the output shaft 14 and the rotary case 10 are interlocked via a planetary gear type speed reduction mechanism 15 provided in the rotary case 10. Has been done.

As shown in FIGS. 3 and 4, a pair of trunnion shafts 16 having a shaft center Y orthogonal to the motor shaft center X are provided on the outer periphery of the swash plate 9 so as to rotate the trunnion shafts 16. A bearing bracket 17 having a pair of engaging recesses 17a that are freely pivotally supported is detachably fixed to the inner bottom surface of the drive chamber D by a positioning pin 28. Here, a pair of engaging portions 26 is formed by the pivotal structure of the trunnion shaft 16 and the engaging recess 17a.

As shown in FIG. 5, the bearing bracket 1
A through hole 17b for penetrating the rotary shaft 5 is formed in the center of the shaft 7, and a pair of upper and lower contacts for setting an inclination angle of the swash plate described later by contact with the back surface of the swash plate 9. This regulation surface 17c is provided. That is, the body case 1
Is formed with a pair of upper and lower hydraulic cylinders 18 and 19 for changing the swash plate angle with respect to the axis Y of the trunnion shaft 16, and oil passages 1 and h to the hydraulic cylinders 18 and 19. When the plunger 18a is supplied and advanced, the inclination angle of the swash plate 9 is set to be large as shown in FIG. 1 to bring about a low speed state, and conversely, pressure oil is supplied only to the hydraulic cylinder 19 to cause the plunger 19a to move. When the vehicle advances, the inclination angle of the swash plate 9 is set small as shown in FIG. 2 to bring about a high speed state.

On the contact control surface 17c, it is possible to change the speed ratio between the low speed state and the high speed state by changing the protrusion amount.

Further, as shown in FIG. 8, the bearing bracket 1
7 has a large diameter through hole 17b, the rotary shaft 5
The supply of the lubricating oil to the bearing 27 that supports the end of the bearing may be promoted.

As a method for assembling the swash plate 9 to the drive chamber D, the bearing bracket 17 is fixed to the inner bottom surface of the drive chamber D from its opening by two positioning pins 28. Then, the trunnion shaft 16 protruding from the outer periphery of the swash plate 9 is directly supported by an engaging recess 17a provided in the bearing bracket 17 while directly looking at the trunnion shaft 16. After that, the cylinder block 7 having the thrust plate 8 and the plunger 6 group is externally fitted to the rotary shaft 5 and the opening is closed by the hydraulic block 3.

FIG. 6 shows a hydraulic circuit diagram for driving the hydraulic motor M. In the figure, reference numeral 20 denotes a traveling control valve, which is operated by switching to a mechanical type or a hydraulic pilot type in cooperation with a steering lever (not shown) to supply pressure oil to the port P1 or port P2 to supply the hydraulic motor M. Can be driven in the normal direction or in the reverse direction.
Reference numeral 21 is a forward rotation drive oil passage f and a reverse rotation drive oil passage r.
Is a shuttle valve for high pressure selection that is connected in communication with and supplies the selected pressure oil for forward rotation drive or reverse rotation drive to the hydraulic cylinder 18 or 19 for changing the swash plate angle.
Reference numeral 22 denotes a hydraulic pilot type flow path switching valve interposed between the shuttle valve 21 and the hydraulic cylinders 18 and 19, and in a normal state where the pilot pressure is not applied, as shown in the figure, the pressure from the shuttle valve 21 is reduced. When oil is supplied to the oil passage 1 to the hydraulic cylinder 18 and the oil passage h to the other hydraulic cylinder 19 is communicated with the drain oil passage d, and pilot pressure is applied, pressure oil from the shuttle valve 21 is applied. Is supplied to the oil passage h to the hydraulic cylinder 19 and the oil passage 1 to the other hydraulic cylinder 18 is connected to the drain oil passage d. The shuttle valve 2 is attached to the hydraulic block 3.
1, flow path switching valve 22 and counter balance valve 2
3 is incorporated, and a shockless mechanism 24 is incorporated in the hydraulic block 4.

The flow path switching valve 22 is normally in a state in which no pilot pressure is applied, and pressure oil is supplied only to the low speed hydraulic cylinder 18, so that the swash plate 9 moves at a low speed as shown in FIG. When the pilot valve 25 is pressed and held in the posture and the pilot valve 25 is switched by pedal operation to apply the pilot pressure to the flow path switching valve 22 and the flow path switching valve 22 is switched to the reverse position,
Pressure oil is supplied only to the hydraulic cylinder 19 for high speed, and as shown in FIG. 2, the swash plate 9 is tilted in a high-speed posture and is pressed and held.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a variable displacement hydraulic motor according to the present invention in a low speed state.

FIG. 2 is a vertical sectional side view of a variable displacement hydraulic motor according to the present invention in a high speed state.

FIG. 3 is a front view showing a swash plate support portion.

FIG. 4 is a side view of a main portion of a swash plate supporting portion.

FIG. 5 is a perspective view of a bearing bracket

[Fig. 6] Hydraulic circuit diagram

FIG. 7 is a side view showing a state in which the hydraulic motor is mounted on the traveling device.

FIG. 8 is a front view showing a swash plate support portion according to another embodiment.

[Explanation of symbols]

 1 Main Body Case 6 Plunger 7 Cylinder Block 9 Swash Plate 16 Trunnion Shaft 17 Bearing Bracket 17a Engagement Recess 17c Contact Limiting Surface 18 Hydraulic Cylinder 19 Hydraulic Cylinder D Drive Chamber Y Axis Core

Claims (3)

[Claims] 1. A cylinder block (7) having a large number of axial type plungers (6) arranged therein is rotatably supported by a drive chamber (D) formed in a main body case (1), and the drive chamber is also provided. A swash plate (9) for receiving the tip end of each plunger (6) is fixedly installed in the inner part of (D), and the swash plate (9) can be tilted about an axis (Y) of the main body case ( 1) Supports the plunger (6)
A swash plate support structure for a variable displacement hydraulic motor, in which a main body case (1) is equipped with hydraulic cylinders (18) and (19) for pushing and tilting a swash plate (9) from the opposite side to the swash plate. (9) A pair of trunnion shafts (16) projectingly provided on the outer periphery, and each trunnion shaft (16) provided on a bearing bracket (17) disposed inside and inside the drive chamber (D). Swash plate support structure of the variable displacement hydraulic motor pivotally supported in the engaging recess (17a) of FIG. 2. The pair of engaging recesses (17a) are integrally formed via a bearing bracket (17).
The swash plate support structure for the variable displacement hydraulic motor described in. 3. The bearing bracket (17) is provided with respective contact control surfaces (1) of the swash plate (9) in a low speed position and a high speed position.
7c) is provided, The swash plate support structure of the variable displacement hydraulic motor of Claim 1 or 2 provided.