JPH0219307B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a swash plate type variable displacement hydraulic rotating machine suitable for use as a variable displacement swash plate pump or motor that can be tilted in both directions.

FIGS. 1 and 2 show a swash plate pump as a hydraulic rotary machine according to the prior art.

In the figure, 1 is a casing forming the main body of the swash plate pump, 2 is a rotating shaft provided by protruding into the casing 1, and 3 is an annular shape fixed to the casing 1 with a pin or the like (not shown). This is the valve plate. Suction/exhaust ports 4, 5 are bored in the valve plate 3, and the suction/exhaust ports 4, 5 are always in communication with suction/exhaust passages 6, 7 provided in the casing 1. Reference numeral 8 denotes a cylinder block. One end surface of the cylinder block 8 is slidably in close contact with the valve plate 3, and the rotating shaft 2 passes through the center thereof. The cylinder block 8 is connected to the rotating shaft 2 by a connecting member 9 such as a spline or a key provided between the inner peripheral part of the cylinder block 8 and the outer peripheral part of the rotating shaft 2. Rotationally driven by. The cylinder block 8 has a plurality of cylinder chambers 10, 10, . The piston 11 is formed with a spherical tip 11A, and the spherical tip 11A is fitted into the shoe 12, so that the piston 11 is swingably supported by the shoe 12.

Next, 13 is a swash plate, and the swash plate 13 faces the cylinder block 8 in an inclined state.
A shoe 12 is in contact with the surface thereof. The shoe 12 is guided by shoe pressing members 14, 14 provided on the swash plate 13 and slides on the surface of the swash plate 13. 15A, 15B are support shafts provided opposite to the swash plate 13, each of the support shafts 15A, 15B is orthogonal to the axis A-A of the rotating shaft 2, and each of the pistons 11
An axis line B along a plane including the entire center of the spherical part 11A of
-B, and each support shaft 15A, 15
The tip of B is in the recess 1A, 1 formed in the casing 1.
It is fitted and supported in B via bearings 16A and 16B. The support shafts 15A and 15B provided on the axis B-B are the axis A of the rotation shaft 2 of the swash plate 13.
- It forms the center axis of tilting for A.

In the figure, reference numeral 17 denotes a suction/discharge passage bored in the cylinder block 8, and as the cylinder block 8 rotates, the suction/discharge passage 17 intermittently communicates the cylinder chamber 10 with the suction/discharge ports 4, 5 provided on the valve plate 3. It is configured so that it can be done. Also, 18A, 18
B is an operation pin attached to the swash plate 13, and by operating the operation pins 18A and 18B, the swash plate 1
3 can be tilted and rotated about support shafts 15A and 15B.

The conventional swash plate pump has the above-mentioned configuration, and among the suction/discharge ports 4, 5 and suction/discharge passages 6, 7, port 4 and passage 6 are on the suction side, and port 5 and passage 7 are on the discharge side. The operation will be explained below. First, FIG. 1 shows a state in which the swash plate 13 is at the maximum tilt position. Therefore, when the rotating shaft 2 is rotated using a drive mechanism (not shown) such as an engine, the cylinder block 8 is also rotated at the same time via the connecting member 9. The cylinder block 8
Due to the rotation, the shoe 12 fitted into the tip ball portion 11A of the piston 11 is guided along the shoe holding member 14, so that the shoe 12 slides on the swash plate 13. The swash plate 13 is aligned with the axis of the cylinder block 8,
That is, since the piston 11 is inclined with respect to the axis A--A of the rotating shaft 2, the piston 11 reciprocates within the cylinder chamber 10 while the cylinder block 8 is rotating.
During the suction stroke when the piston 11 extends from the cylinder chamber 10, the suction and exhaust passage 17 communicates with the port 4 to supply low pressure fluid into the cylinder chamber 10, and during the discharge stroke when the piston 11 enters the cylinder chamber 10, the suction and exhaust passage 17 communicates with the port 4 to supply low pressure fluid into the cylinder chamber 10. 17 communicates with port 5, and high pressure fluid pressurized by piston 11 is discharged.

Next, in order to change the capacity of the pump, the operating pin 18 may be rotated in the direction of the arrow in FIG. 1 using a suitable drive means. As a result, the swash plate 13 rotates about the axis BB of the support shafts 15A, 15B, and the stroke of the piston 11 during one revolution of the cylinder block 8 changes.

By the way, at the maximum tilting position shown in FIG. 1, the piston 11 at the top in the figure is at the bottom dead center position where it has been extended to the maximum, and the piston 11 at the bottom in the figure is at the top dead center position where it has entered the maximum extent. It is shown. At the top dead center position of the piston 11 mentioned above, the cylinder chamber 1 indicated by the interval l in FIG.
The volume within 0 is a dead volume in which the high-pressure fluid remains without being discharged even during the discharge stroke and is returned to the low-pressure side. Therefore, this dead volume becomes an apparent amount of leakage, and the volume of the pump decreases. Therefore, it is preferable to reduce the dead volume described above from the viewpoint of improving the volumetric efficiency of the pump.

However, in the conventional swash plate pump described above, the tilting operation is performed by the support shafts 15A and 15B.
This is done by rotating the swash plate 13 about the axis B--B of the tilting axis. Therefore, when the piston 11 is tilted in the capacity decreasing direction from the maximum tilt position, the bottom dead center position of the piston 11 becomes the position where it has entered the cylinder chamber 10 from the state shown in FIG. The position is extended from. For this reason, when the stroke of the piston 11 at the time of maximum tilting is S, and the stroke of the piston 11 when the capacity is reduced is S', the dead volume increases by an interval corresponding to approximately S-S'/2. It turns out. As a result, the smaller the tilting angle of the swash plate 13, the more the dead volume increases, resulting in a disadvantage of lowering the volumetric efficiency of the pump. Furthermore, as described above, when the dead volume becomes large, the high pressure fluid flows into the low pressure side, which causes pulsation and increases noise.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide a swash plate type variable displacement hydraulic rotating machine that can maintain a small dead volume even when the tilt angle of the swash plate is changed in both directions. With the goal.

In order to achieve the above object, the present invention includes a rotating shaft provided by protruding into a casing, a cylinder block that fits into the rotating shaft and rotates together with the rotating shaft, and a cylinder block that is bored in the axial direction of the cylinder block. A plurality of cylinder chambers are provided, and the cylinder is slidably inserted into each of the cylinder chambers, and is located between a top dead center position at which the cylinder reaches its maximum extent inside the cylinder block and a bottom dead center position at which it extends maximum outside the cylinder block. A reciprocating piston, a shoe located outside the cylinder block and swingably provided at the tip of each piston, and a state in which the shoe is tiltably facing the cylinder block and in sliding contact with the shoe. In the swash plate type variable displacement hydraulic rotating machine, the swash plate includes a swash plate that reciprocates each piston between a bottom dead center and a top dead center as the cylinder block rotates. Two tilting center shafts are provided on the sides of the top dead center and bottom dead center of each piston, and arcuate guide grooves are provided in the casing to guide the respective tilting center shafts, and each of the tilting The present invention is characterized in that a tilting drive mechanism is provided that tilts the swash plate while guiding the central shaft along each of the arcuate guide grooves.

With this configuration, the tilting drive mechanism uses one of the two tilting central axes as a fulcrum and guides the other tilting central axis along the arcuate guide groove. When the swash plate is operated, the swash plate tilts about one of the tilting central axes. On this occasion,
The piston located on one side of the tilting center axis maintains its initial position and reaches the top dead center position, and the dead volume does not change.

Embodiments of the present invention will be described below with reference to FIGS. 3 to 6.

In this figure, the same components as those in FIGS. 1 and 2 are designated by the same reference numerals, and the explanation thereof will be omitted. However, the feature of the present invention is that the swash plate 21 is provided with two sets of support shafts 22A, 22B and 23A, 23B as tilting center shafts. Each set of support shafts 22A, 22B, 2
3A, 23B are along the plane including the entire center of the spherical portion 11A of each piston, and are along the axes C-C, DD and the spherical portion 1 at the upper and lower dead center positions of the piston 11.
They are located on the tilting center axes E-E and F-F, which are perpendicular to each other at the centers _O1 and _O2 of 1A. Each set of support shafts 22A, 22B, 23A, and 23B are formed so as to be parallel to the tilting center axes EE and FF. Further, arc-shaped guide grooves 24A, 24B and 25A, 25B are formed in the casing 1, and each support shaft 22A, 22B, 23A, 23B is connected to the guide groove 24A, 24B, 25A, 25B, respectively.
The swash plate 21 is rotatably supported by the casing 1 by being fitted into the casing 1 via bearings 26, 26, . Each support shaft 22A, 22B, 23A, 2
3B are guide grooves 24A, 24B, 25A, and 25, respectively, at the zero tilt rotation position as shown in FIG.
It is in a position where it touches the end of B. On the other hand, when the upper piston 11 in the figure is tilted in the direction where it reaches the bottom dead center, the support shafts 22A and 22B are moved into the guide groove 2.
4A, 24B, and when the lower piston 11 in the figure is at the bottom dead center, the support shaft 2
3A and 23B are slidably guided along guide grooves 25A and 25B.

Reference numerals 27A and 27B are operating cylinders serving as a tilting drive mechanism for tilting the swash plate 21 provided in the casing 1;
B indicates cylinder holes 28A, 28B and a piston 2 slidably provided in the cylinder holes 28A, 28B.
9A, 29B, and springs 30A, 30B that press the respective pistons 29A, 29B to the right in FIG. And piston 29A, 2
9B defines the cylinder holes 28A and 28B into oil chambers G ₁ , G ₂ , H ₁ and H ₂ , respectively. oil room
G ₁ , G ₂ , H ₁ , and H ₂ are pipes 31, 32, and 3, respectively.
3 and 34, it is possible to switch between a hydraulic power source or a tank (both not shown). Further, the pistons 29A and 29B have grooves 35 in the radial direction.
A, 35B are formed, and operation pins 18A, 18B
Operating rods 36A and 36B protruding from are fitted in and retractable.

The hydraulic rotating machine according to the present invention has the above-mentioned configuration, and its operation will be explained next. In FIG. 3, the swash plate 21 is at the zero tilt rotation position of the rotary shaft 2, and all the pistons 11 are placed at the top dead center position where they have entered the cylinder chamber 10 to the maximum extent. For this reason, the distance L between the end surface of each piston 11 and the end wall of the cylinder chamber 10 becomes minimum, and the cylinder chamber 1
The space within 0 is the minimum. Even if the cylinder block 8 is rotated in this state, the piston 11 does not stroke within the cylinder chamber 10, and no oil is sucked or discharged. In this zero tilt rotation state, the pipes 32 and 34 are connected to the tank, and the oil chambers G ₁ and
The pistons 29A, 29B are pushed to the right in the figure by the hydraulic pressure in _H1 and the spring force of the springs 30A, 30B, respectively, and the support shafts 22A, 22B, 23A, 2
3B are guide grooves 24A, 24B, 25A, respectively.
It is placed in contact with the end of 25B.

Therefore, when the pipe 32 is connected to a hydraulic pressure source and the other pipe 31 is opened to a tank, pressure oil is supplied to the oil chamber _G2 , and the piston 29A is displaced to the left in the figure against the spring 30A. As a result, the operating rod 3
6A follows the piston 29A and is displaced to the left in the figure. On the other hand, the piston 29B is displaced to the right in the figure by the pressing force of the spring 30B. For this purpose, swash plate 2
1 is rotated about the support shafts 23A and 23B as fulcrums, and is displaced in the direction of increasing tilt. At this time, the support shafts 22A, 22B are slidably guided along the guide grooves 24A, 24B. That is, the swash plate 21 rotates around a tilting center axis FF passing through the center of the spherical portion 11A of the piston 11 at the bottom in the figure. Due to this rotation of the swash plate 21, the piston 11 at the top in the figure extends from the cylinder chamber 10, and its position becomes the bottom dead center position, and the piston 11 at the bottom in the figure maintains its original position and moves to the top dead center position. becomes. Then, in accordance with the increase in the amount of extension of the piston 11 at the bottom dead center position, its stroke increases, and the capacity of the pump increases, and the piston 11 is displaced to the maximum tilting position as shown in Fig. 6. . Therefore, by controlling the hydraulic pressure supplied into the oil chamber _G2 via the pipe 32, the swash plate 21 can be moved from the zero tilt position shown in FIG. 4 to the maximum tilt position shown in FIG. It can be held in any position between. In this way, the tilting of the swash plate 21 is performed around the tilting center axis FF passing through the center of the spherical portion 11A of the piston 11 at the bottom in the figure, which is the top dead center position. The piston 11 does not change regardless of the tilting position. Therefore, the dead volume has a value determined by the interval L, and is always constant.

The above-mentioned operation connects port 4 and passage 6 to the suction side,
Although the description has been made with port 5 and passage 7 on the discharge side, next we will explain the case where port 5 and passage 7 are on the suction side, port 4 and passage 6 are on the discharge side, and cylinder block 8 is rotated in the opposite direction to the above. do. In this case, the oil chamber is
Supply hydraulic pressure inside _H2 . The piston 29B is displaced to the left in the figure against the spring 30B by this hydraulic pressure. On the other hand, since the piston 29A is pressed to the left in the figure by the spring 30A, the piston 29A is displaced to the left in the figure in response to the displacement of the piston 29B to the right in the figure. As a result, the swash plate 21 is
It is rotated about 2A and tilted in the direction shown by the dashed line in FIG. Therefore, the piston 11 at the top in the figure is at the top dead center position.
The distance L between the cylinder chamber 10 and the inner wall of the cylinder chamber 10 does not change during tilting, and the dead volume is always kept constant.

In addition, in the above-mentioned embodiment, the case where the hydraulic rotary machine according to the present invention is used as a hydraulic pump has been described, but it goes without saying that it can be used as a hydraulic motor. When used as a hydraulic motor, if a hydraulic pump is used to supply pressure oil to the hydraulic motor as a hydraulic pressure supply source to the operation cylinders 27A and 27B, the capacity of the hydraulic motor is adjusted according to the discharge pressure of the hydraulic pump. can be changed. In addition, an operating cylinder 27 is used as a tilting drive mechanism.
A and 27B have been described, but instead of this, the operation pins 18A and 18B may be mechanically operated using a rack and pinion mechanism or the like, or may be configured to be tilted and driven manually. Furthermore, although the central axis of tilting of the swash plate 21 has been described as being disposed at each of the upper and lower dead center positions of the piston 11, the dead space can also be reduced by arranging it near each of the dead center positions.

As described in detail above, according to the swash plate type variable displacement hydraulic rotary machine according to the present invention, the piston is positioned on the top dead center or bottom dead center side, and the tilting center axis of the swash plate is set at 2. The casing is provided with arcuate guide grooves for guiding each of the tilting center shafts, and the tilting drive mechanism guides each of the tilting center shafts along each of the arcuate guide grooves while driving the swash plate. Since the configuration is such that the swash plate is tilted, it is not only possible to perform forward/reverse hydraulic rotation that allows tilting in both directions using either one of the tilting central axes as a fulcrum, but also allows the swash plate to rotate on either side, which is the fulcrum when the swash plate is tilted. The piston can maintain its position before and after the tilting operation, and the dead volume of the cylinder guide can always be kept constant. Therefore, it is possible to improve the volumetric effect of the hydraulic rotary machine, and also to prevent the occurrence of pulsation and reduce noise.

[Brief explanation of drawings]

1 and 2 show the prior art, in which FIG. 1 is a longitudinal sectional view of a swash plate type variable displacement hydraulic rotating machine, FIG. 2 is a sectional view in the direction of the - arrow in FIG.
3 to 6 show embodiments of the present invention, in which FIG. 3 is a longitudinal cross-sectional view of a swash plate type variable displacement hydraulic rotating machine, and FIG. 4 is a cross-sectional view in the direction indicated by the − arrow in FIG. 3. , FIG. 5 is a sectional view taken in the direction indicated by the - arrow in FIG. 4, and FIG. 6 is a sectional view similar to FIG. 3 showing a different operating state. DESCRIPTION OF SYMBOLS 1... Casing, 2... Rotating shaft, 3... Valve plate, 8... Cylinder block, 10... Cylinder chamber, 11... Piston, 21... Swash plate, 22
A, 22B, 23A, 23B...Support shaft, 24
A, 24B, 25A, 25B...Guide groove, 27
A, 27B...Operation cylinder.

Claims (1)

[Claims] 1 A rotating shaft inserted into the casing,
a cylinder block that fits onto the rotating shaft and rotates together with the rotating shaft; a plurality of cylinder chambers bored in the axial direction of the cylinder block; and a cylinder block that is slidably fitted into each cylinder chamber; a piston that reciprocates between a top dead center position that has entered the cylinder block to the maximum extent and a bottom dead center position that has reached a maximum extent outside the cylinder block; The cylinder block rotates with the provided shoes movably facing the cylinder block and in sliding contact with each other, thereby moving each piston between the bottom dead center and the top dead center. In a swash plate type variable displacement hydraulic rotating machine comprising a swash plate that reciprocates between the swash plates, the swash plate is provided with two rotation center axes on the sides where each piston is at the top dead center and the bottom dead center, The casing is provided with an arcuate guide groove for guiding each of the tilting center shafts, and the swash plate is tilted while guiding each of the tilting center shafts along each of the arcuate guide grooves. A swash plate type variable capacity hydraulic rotary machine characterized by being equipped with a drive mechanism.