JPH0340236B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable hydraulic actuator,
In particular, the present invention relates to a variable hydraulic actuator that is used as a hydraulic motor or hydraulic pump that is variable in three fixed speeds: high, medium and low.

In reality, variable hydraulic motors consisting of variable actuators have traditionally been used in equipment that requires constant three-speed running at high, medium, and low speeds, such as bulldozers and shovel dozers. . When this variable hydraulic motor is used, the speed is changed continuously from high speed to low speed, so the entire pumping device becomes larger and requires a large volume when mounted on a bulldozer or shovel dozer for use. There was an inconvenience. Also,
In order to continuously vary the device itself, a large piston thrust force is required to maintain the desired inclination state of the inclination plate, which has disadvantages and inconveniences such as the need to increase the strength of the parts. Therefore, it has been desired to provide a hydraulic motor that has a simple structure, a small volume, and can be changed to only three constant speeds: high, medium, and low.

Therefore, an object of the present invention is to provide a new variable hydraulic actuator that can be used as a hydraulic motor or hydraulic pump that is variable only between three constant speeds: high, medium and low. , a casing, a rotating shaft pivotally connected to the casing, a cylinder block connected to the rotating shaft, and a swash plate on which a shoe fitted to a plunger inserted into the cylinder block slidably abuts. , a hydraulic actuator comprising a plate installed in a casing adjacent to the cylinder block, and the swash plate has a smooth surface on the abutting surface of the shoe, and has one vertical surface and two inclined surfaces on the opposite surface. When one of the pair of pressing members formed on the casing is activated, one of the two inclined surfaces is brought into surface contact with the casing, and when the pair of pressing members is not activated, the vertical surface is brought into surface contact with the casing. It is formed so that its angle of inclination can be changed by rotating it up and down so as to make it move.

The present invention will be explained below based on the illustrated preferred embodiments.

FIG. 1 shows a circuit diagram when the variable hydraulic actuator according to the present invention is used as a hydraulic motor A. When the engine B operates, oil from the oil pump C passes through the outward path D and increases the hydraulic pressure. After reaching the motor A and driving the hydraulic motor A, the oil returns to the oil pump C via a return path E. As shown in FIG. 2, this hydraulic motor A has a casing 1, a rotating shaft 2, a cylinder block 3, a swash plate 4, and a plate 5.

The casing 1 has an inner cavity 10 therein, and the rotating shaft 2 is pivotally mounted at the center.
The cylinder block 3, swash plate 4, and plate 5 are provided within the inner space 10.
The casing 1 also includes a suction oil passage 11, a discharge oil passage 12, and a pair of auxiliary oil passages 13a, 13b.
are drilled, and each of the auxiliary oil passages 13
A pair of auxiliary cylinders 1 each communicating with a and 13b
4a and 14b are provided. A pressing member is fitted in each of the auxiliary cylinders 14 and is slidable by hydraulic pressure acting through each auxiliary oil passage 13, and this pressing member is connected to the auxiliary plunger 15 (1).
5a, 15b) and auxiliary shoe 16 (16a, 16
b), in which an auxiliary shoe 16 is rotatably fitted to the tip of an auxiliary plunger 15. Note that the suction oil passage 11 is connected to the outgoing route D (first
(see figure), and communicates with the above-mentioned discharge oil passage 12.
is connected to the return route E (see FIG. 1). Further, oil is guided to the auxiliary oil passages 13a and 13b from the oil pump C (see FIG. 1) via a separate route and a control device (not shown).

The rotating shaft 2 is pivotally mounted at the center of the casing 1 via bearings 20 and 21 and sealed by a sealing member 22, and the cylinder block 3 is connected to the cylinder block 3 in the center by a spline connection in the inner space 10. The cylinder block 3 is held in such a manner that it can rotate within the inner space 10. Note that a joint hole 23 is formed at one end of the rotary shaft 2 to which a rotary shaft (not shown) of, for example, a speed reducer is connected. Furthermore, it goes without saying that the method of connecting the cylinder block 3 to the rotating shaft 2 may be arbitrarily selected other than the spline connection described above.

The cylinder block 3 is formed into a thick disk shape as a whole, and a plurality of cylinders 30 are bored therein. A plunger 31 is inserted into the cylinder 30 from an opening at one end, and a shoe 32 is rotatably fitted to the tip of the plunger 31. The front end surface of this shoe 32 is brought into contact with the swash plate 4 . A port 33 is formed at a portion corresponding to the center of the other end of the cylinder 30, passing through the thickness of the cylinder block 3. This port 33 is connected to the suction oil passage 11 or the discharge oil passage 12 depending on the rotation of the cylinder block 3.
Although it is through the plate 5, it communicates with the. Further, this cylinder block 3 is always connected to a plate 5.
Further, a pressing device is provided for constantly pressing the shoe 32 against the swash plate 4. That is, a space of an appropriate size is formed in the vicinity of the center of the cylinder block 3 and adjacent to the rotating shaft 2, and a stopper 34 is provided protruding from the cylinder block 3 in this space, and one piece is attached to the stopper 34. 35a is locked, one end of the spring 36 is held by this piece 35a, and the other end of the spring 36 is locked by the other piece 35b, and the rod 37 passing through the cylinder block 3 is attached to the other piece 35b. A cam 38 is brought into contact with the tip of the rod 37, and a stopper piece 39 attached to the shoe 32 is brought into contact with the cam surface of the cam 38. That is, this pressing device presses the cylinder block 3 against the plate 5 by the repulsive force of the spring 36, and also presses the cylinder block 3 against the plate 5.
is pressed against the swash plate 4 by a stopper piece 39. Therefore, when the inside of the cylinder 30 changes from an unpressurized state to a pressurized state, oil may leak from between the cylinder block 3 and the plate 5 and the rotation of the cylinder block 3 may be inhibited. Thereby, the cylinder block 3 can be smoothly rotated and the rotating shaft 2 can be rotated smoothly.

The swash plate 4 is formed to have a donut-shaped planar shape as a whole, as shown in FIG. 3A, and a wedge-shaped side surface shape as a whole, as shown in FIG. 3B. has been done. The adjacent surface on the casing 1 side consists of a vertical surface portion 40 and two sloped surface portions 41a and 41b at arbitrary angles, and the adjacent surface on the shoe 32 side is formed into an inclined surface with a larger angle than the sloped surface portion 41. In addition, a smooth surface portion 42 is provided to allow the shoe 32 to slide. Furthermore, ball holes 43a and 43b are formed at the branching portions between the vertical surface portion 40 and the inclined surface portions 41a and 41b, and ball holes 43a and 43b are formed in the inner wall of the casing 1 at positions corresponding to these ball holes 43a and 43b. Balls 44a and 44b are held between the ball holes (not shown). Therefore, each auxiliary cylinder 1
When there is no hydraulic pressure in 4a, 14b, the swash plate 4 is always supported by the pressing device of the cylinder block 3 with only its vertical surface portion 40 in surface contact with the inner wall of the casing 1 (see Fig. 4A). ). However, when hydraulic pressure acts in one of the auxiliary cylinders 14b, the auxiliary plunger 15b moves forward, and the auxiliary shoe 16b presses one inclined surface portion 41b against the swash plate 4, and presses the other inclined surface portion 41a against the inner wall of the casing 1. Make surface contact (see Figure 4 B). At this time,
The ball 44a in the upper ball hole 43a is connected to the swash plate 4.
It becomes the center of undulation rotation. Next, from the state where the vertical surface portion 40 of the swash plate 4 is in surface contact with the inner wall of the casing 1 (see FIG. 4A), the other auxiliary cylinder 1
When hydraulic pressure acts in the swash plate 4a, the auxiliary plunger 15a moves forward, the supplementary shoe 16a presses the other inclined surface portion 41a of the swash plate 4, and the one inclined surface portion 4
1b into surface contact with the inner wall of the casing 1 (fourth
(See Figure C). At this time, the ball 44b in the lower ball hole 43b becomes the center of the up-and-down rotation of the swash plate 4.

Here, the force F acting on the smooth surface portion 42 of the swash plate 4 is
The relationship between this and the forces fa and fb acting from the pressing member on the two inclined surface portions 41a and 41b of the swash plate 4 will be explained based on FIG.

That is, in the case shown in FIG. 4B, the upper inclined surface portion 41a is brought into surface contact with the casing 1, and at this time, the following equation holds true for fb acting from the lower pressing member.

fb＞b ₂ /a ₂ ×F fb＜(b ₂ + l ₂ ) / (a ₂ + l ₂ ) × F In this state, it rotates in a stable state and becomes a low-speed rotating hydraulic motor. be.

Further, in the case shown in FIG. 4C, the lower inclined surface portion 41b is in surface contact with the casing 1.
is in the relationship that the following formula holds true.

fa＞b ₁ /a ₁ ×F fa＜(b ₁ + l ₁ ) / (a ₁ + l ₁ ) × F In this state, it rotates in a stable state and becomes a high-speed rotating hydraulic motor. .

Furthermore, in the case shown in FIG. 4A, none of the inclined surface parts 41 is brought into surface contact with the casing 1,
This is a case where only the vertical surface portion 40 is brought into surface contact with the casing 1, and at this time, the forces fa and fb from each pressing member are zero. That is, the force F is between the center points Oa and Ob of the two balls 44a and 44b. In this state, the motor rotates stably and becomes a medium-speed rotating hydraulic motor.

Incidentally, it goes without saying that the swash plate 4 is formed with an opening 45 to allow the rotation shaft 2 to pass therethrough, and the bearing 2 is formed when the swash plate 4 rotates up and down.
Considerations have been made, such as forming a groove 46 to avoid a collision with the shoe 32 and a notch 47 to avoid a collision between the stopper piece 39 attached to the shoe 32 (see FIG. 3). The swash plate 4 rotates up and down around one of the balls 44a and 44b, but instead of the ball 44, a chevron-shaped, hemispherical, etc. protrusion is provided at a position corresponding to the ball hole 43. Alternatively, horizontal ribs or the like may be provided in a protruding manner, and a corresponding receiving portion may be formed on the adjacent inner wall of the casing 1 so as to enable the up-and-down rotation.

The plate 5 is interposed between the cylinder block 3 and the casing 1, and is formed to have a donut shape as a whole as shown in FIG. A suction groove 5 having a substantially half-moon shape formed through the thickness
0 and a discharge groove 51. Also, both grooves 5
A sealing portion 52 is formed between the mutually adjacent ends of the cylinder block 3, which corresponds to the opening area of the port 33 formed in the cylinder block 3. The suction groove 50 communicates with the suction oil passage 11 formed in the casing 1, and the discharge groove 5
Reference numeral 1 communicates with a discharge oil passage 12 which is also formed in the casing 1 . Incidentally, this plate 5 is connected to the port 33 and the oil passage 11 as described above.
Alternatively, since it is in charge of communicating with and blocking the oil passage 12, it is held by an appropriate fixing means so as to be fixed to the inner wall of the casing 1.

The hydraulic motor A according to the embodiment of the present invention configured as described above operates as follows.

First, the engine E is operated to send pressurized oil from the oil pump C to the suction oil path 11 via the outgoing path D. This pressurized oil is fed into the port 33 located above the suction groove 50 via the suction groove 50 communicating with the suction oil passage 11 . Since this port 33 communicates with the cylinder 30, oil enters into the cylinder 30. When oil enters the cylinder 30, the plunger 31 tends to move forward. However, the shoe 32 fitted to the tip of the plunger 31 is in contact with the smooth surface portion 42 of the adjacent swash plate 4, and the movement acting perpendicularly to the smooth surface portion 42 is restricted and the movement in the lateral direction, that is, the smooth surface portion 42 is restricted. Only the secondary movement is induced. Therefore,
As the plunger 31 moves forward, the cylinder block 3 rotates. Note that before the cylinder block 3 rotates, that is, when the oil is in an unpressurized state, the cylinder block 3 is pressed against the plate 5 by the pressing device, and the shoe 32 is pressed against the swash plate 4, so that the plate 5 and the cylinder block 3, and the cylinder block 3 will not be able to rotate due to this, and once the oil is pressurized, the cylinder block 3 will rotate.

Oil is fed into the cylinder 30 as described above, and the feeding and discharge of oil into the cylinder 30 will be explained with reference to FIG. 5. In addition, 33a, 33b, 33c, 33d,
Each symbol 33e indicates a moving position of the port 33.

First, when the port 33 of a certain cylinder 30 is located in one of the blocking portions 52 (upper in the figure), the oil in the cylinder 30 is not discharged. However, when the cylinder block 3 is rotated slightly, the plunger 31 enters into the cylinder 30 and the port 33 (33a in the figure) is inserted into the discharge groove 5.
1, the oil in the cylinder 30 begins to be discharged. When the rotation of the cylinder block 3 progresses and the port 33 (33b in the figure) comes to communicate with the other end of the discharge groove 51, most of the oil in the cylinder 30 is discharged, and the port 33 (33b in the figure) comes into communication with the other end of the discharge groove 51.
When c) reaches the other blocking portion 52 (lower in FIG. 5), the discharge of oil from inside the cylinder 30 is stopped. Further, as the rotation of the cylinder block 3 progresses, the port 33 (33d in the figure) opens into the suction groove 50.
When oil starts to enter the cylinder 30 and the port 33 (33e in the figure) communicates with the other end of the suction groove 50, the cylinder 30 is full of oil. becomes. The cylinder block 3 rotates in this state, and the port 33 moves again to one of the blocking portions 52, returning to the original position to start discharging oil.

Since the above-mentioned operations are carried out in the cylinders 30, which are equipped with a plurality of cylinders, the cylinder block 3 rotates, and the rotating shaft 2 connected thereto is rotationally driven. Therefore, if the pressurized state of the oil is released, the rotational drive of the rotating shaft 2 can be stopped. As mentioned above, even when the oil is in an unpressurized state, the shoe 32 is always pressed against the swash plate 4, so even if pressure is applied or released repeatedly, there will be no risk of oil leakage, etc. Rotating axis 2
This will not result in the inability to rotate.

The above operation is the same regardless of whether the swash plate 4 is in any of the positions A, B, and C in FIG. However, in the case of Fig. 4A, that is, when the vertical surface portion 40 of the swash plate 4 is in surface contact with the inner wall of the casing 1 and stabilized, it becomes a medium speed motor, and in the case of Fig. 4B, that is, the swash plate 4 Upper inclined surface portion 41
If a is in surface contact with the inner wall of the casing 1 and stabilized, it becomes a low-speed motor, and in the case of FIG. It is.
Although the tilting operation of the swash plate 4 has been described above, the auxiliary plunger 15, that is, the auxiliary shoe 16 is not always pressed against the inclined surface portion 41 of the swash plate 4. When the inside of the auxiliary cylinder 14 is in an unpressurized state, the vertical surface portion 40 of the swash plate 4 is in surface contact exclusively with the inner wall of the casing 1;
No thrust is required from the auxiliary plunger 15 at this stage. Furthermore, when the inside of the auxiliary cylinder 14 is pressurized, the inclined surface portion 41 of the swash plate 4 comes into surface contact not only with the auxiliary shoe 16 but also with the inner wall of the casing 1, so that the thrust of the auxiliary plunger 15 is large. It doesn't have to be something. The thrust required for the auxiliary plunger 15 is sufficient as long as it satisfies the above-mentioned formula.

The above configuration and operation are an embodiment of the present invention as a hydraulic motor, but when it is used instead as an embodiment of a hydraulic pump, when rotating with the rotating shaft 2 as a drive shaft, the suction oil passage Of course, it is possible to suck unpressurized oil from 11 and discharge pressurized oil from the discharge oil passage 12, and at that time, high-speed, medium-speed, and low-speed discharge are possible. Of course, it is also possible to do so.

As described above, according to the present invention, it is possible to obtain a variable hydraulic actuator as a hydraulic motor or a hydraulic pump that can be freely changed to three constant speeds: high speed, medium speed, and low speed. Moreover, since it has a simple structure, it is easy to manufacture, increasing the possibility of implementation, and has the advantage of reducing the number of parts, making it economical. Further, when installing and using the device, not only does it not require a large volume, but also the installation and preparation of complicated operating devices are not required, and it has the advantage that it can be used with simple operations.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram when the variable hydraulic actuator according to the present invention is used as a hydraulic motor, Fig. 2 is a longitudinal sectional view showing the hydraulic motor according to the present embodiment, and Fig. 3 A is a front view of the swash plate. , FIG. 3B is a side view of the swash plate, FIGS. 4A, 4B, and 4B are side views showing the operating state of the swash plate, and FIG. 5 is a front view of the plate. 1... Casing, 2... Rotating shaft, 3... Cylinder block, 4... Swash plate, 5... Plate, 1
4a, 14b...Auxiliary cylinder, 15a, 15b
...Auxiliary plunger, 16a, 16b...Auxiliary shoe, 30...Cylinder, 31...Plunger,
32...Show, 40...Smooth surface portion, 41a, 4
1b...Slope portion, 43a, 43b...Ball hole, 44a, 44b...Ball.

Claims (1)

[Claims] 1. A casing, a rotating shaft pivotally connected to the casing, a cylinder block connected to the rotating shaft, and a shoe fitted to a plunger inserted into the cylinder block are slidable. In a hydraulic actuator, the swash plate is composed of a swash plate that contacts the cylinder block, and a plate installed in the casing so as to be adjacent to the cylinder block. A surface portion and two sloped surface portions, one of the two sloped surface portions is brought into surface contact with the casing when either one of the pair of pressing members formed on the casing is activated, and a vertical surface portion is formed when the pair of pressing members formed on the casing is not activated. A variable hydraulic actuator that is formed so that its angle of inclination can be changed by rotating it up and down so that it makes surface contact with the casing. 2. The variable hydraulic actuator according to claim 1, wherein the cylinder block has a pressing device that operates to press the cylinder block against the plate and to press the shoe fitted on the plunger against the swash plate. . 3. The swash plate is formed so as to be able to tilt with one of the balls installed in upper and lower stages adjacent to the casing as the center of its up-and-down rotation. variable hydraulic actuator.