JPH0251074B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic rotating machine used as a hydraulic pump or motor, such as a swash plate type or an oblique shaft type.

FIGS. 1 and 2 show a swash plate type hydraulic pump as a conventional hydraulic rotary machine.

In the figure, 1 is a casing, 2 is a rotating shaft supported by a pair of bearings 3 (however, one not shown), and 4 is a rotary shaft that is press-fitted into the rotating shaft 2. It is a cylinder block fixed by means. The cylinder block 4 has a plurality of cylinders 5, 5, ... bored in its axial direction, and a piston 6 whose one end is supported by a swash plate (not shown) can slide inside each cylinder 5. Each piston 6 is reciprocated by the rotation of the rotating shaft 2.

Reference numeral 7 designates a pressing plate as a valve plate crimping mechanism that rotates together with the cylinder block 4. The pressing plate 7 has auxiliary piston portions 9, 9, . Each auxiliary piston part 9 is fitted into each cylinder 5 of the cylinder block 4, and has a sliding surface 7A that is brought into sliding contact. Further, a communicating passage 10 having a diameter smaller than that of each cylinder 5 is bored in the axial direction of the auxiliary piston portion 9, and each communicating passage 10 opens to the sliding surface 7A of the pressing plate 7. Furthermore, a spring seat 11 is provided in the middle of each communication path 10.
is provided, and a spring 12 is stretched between the spring seat 11 and the end surface of the piston 6.

Next, the valve plate 8 has one side facing the sliding surface 7A of the pressing plate 7.
The other surface has a sliding surface 8A that comes into sliding contact with the pin 13.
is fixed to the casing 1 by. and,
A suction port 14 and a discharge port 15 are bored in the valve plate 8 as a pair of suction/discharge ports, and the suction port 14 and the discharge port 15 are connected to the suction passage 16 and the discharge passage 1, respectively, which are bored in the casing 1.
7, and intermittently communicates with a communication passage 10 formed in the press plate 7 while the cylinder block 4 and the press plate 7 rotate together (see Fig. 2). ).

In addition, in the figure, 18, 18, . . . are seal members provided between the auxiliary piston portion 9 and the cylinder 5. The swash plate type hydraulic pump according to the prior art has the above-mentioned configuration, and when the rotating shaft 2 is rotated by a driving means (not shown) such as an engine,
Cylinder block 4 rotates together with pressing plate 7.
For this reason, the piston 6 reciprocates within the cylinder 5 due to the cylinder block 4 and the swash plate provided at an angle with respect to the rotating shaft 2, and the communication passage 10 communicating with the cylinder 5 is intermittently connected to the valve plate 8. Suction port 1
4 or the discharge port 15, a pumping action is performed.

Thus, when the pump is driven under high load, the pressure inside the discharge port 14 becomes high. For this reason, the press plate 7 includes a communication passage 10 and a discharge port 14.
The leaking oil between the valve plate 8 and the valve plate 8 generates a separating force that tends to separate the press plate 7 from the valve plate 8. In response to this opening force, a pressing force is applied to the pressing plate 7 against the valve plate 8 by the spring force of the spring 12 and the fluid pressure acting on the end face of the auxiliary piston part 9 within the cylinder 5. By designing this pressing force to be larger than the above-mentioned opening force, leakage of fluid from between the sliding surface 7A of the pressing plate 7 and the sliding surface 8A of the valve plate 8 is prevented. It is prevented. Here, when the groove width of the suction/exhaust ports 14 and 15 is b and the diameter of the cylinder 5 or piston 6 is d, the above-mentioned opening force is determined by the groove width b, and the pressing force is determined by the diameter d. . For this reason, the suction and exhaust ports 14, 15
By making the groove width b as small as possible with respect to the diameter d of the cylinder 5, the pressing force is increased and excessive leakage of fluid is prevented.

However, the prior art pumps described above had a number of drawbacks.

First of all, the diameter of the communication path 10 is the diameter of the suction/discharge port 1.
It is limited by the groove width b of 4 and 15. Therefore, if the groove width b of the suction/discharge ports 14 and 15 is made smaller, the flow resistance of the communication passage 10 will increase when the pump is driven at high speed, the pressure loss will increase, and a large load will be placed on the pump, so the machine The disadvantage was that the efficiency was significantly reduced and the self-priming ability was also reduced.

Second, the high-pressure oil in the communication passage 10 does not flow into the discharge passage 17 even during the pump discharge stroke, and the volume of the communication passage 10 out of the compression due to the bulk modulus of the fluid becomes a dead volume, resulting in an apparent leakage amount. I become confused. For this reason, there was also a drawback that the volumetric efficiency of the pump was reduced.

Thirdly, since the auxiliary piston portion 9 protrudes into the cylinder 5, the stroke S of the piston 6 is limited in order to avoid contact with the auxiliary piston portion 9 when the piston 6 is at its top dead center position. Therefore, in order to sufficiently increase the stroke S of the piston 6, the cylinder block 4 must be lengthened in its axial direction, which has the disadvantage of increasing the size of the entire device.

The present invention was developed in view of the above-mentioned drawbacks of the prior art, and it reduces the flow resistance of the suction and discharge flow paths when used as a pump or motor, improves self-priming performance and mechanical efficiency, and increases the stroke of the piston. An object of the present invention is to provide a hydraulic rotary machine capable of reducing dead volume.

In order to achieve this object, the hydraulic rotating machine according to the present invention has a configuration including a rotating shaft rotatably supported by a casing, and a rotating shaft arranged in the casing so as to rotate together with the rotating shaft. a plurality of cylinders bored in the axial direction of the cylinder block; a plurality of pistons provided in each cylinder so as to be able to reciprocate; A plurality of recesses are formed at corresponding positions to have a diameter larger than that of each cylinder, and a plurality of auxiliary piston parts are formed at the end of the cylinder block and fit into the respective recesses on one side. A pressing plate having a diameter larger than the diameter of the piston is formed in the axial direction at the position of each auxiliary piston portion of the pressing plate so as to communicate with each cylinder, and the piston has a top dead end. A plurality of auxiliary cylinders that can be entered when the cylinder block and the pressing plate are rotated together, a valve plate provided on the other side of the pressing plate, and The valve plate includes a pair of suction/exhaust ports that are bored in the valve plate so as to communicate intermittently with each auxiliary cylinder, and have a groove width larger than the diameter of the piston.

In this way, the auxiliary cylinder of the press plate and the suction/exhaust port of the valve plate are formed to have a diameter larger than the diameter of the piston that reciprocates within the cylinder block, and the auxiliary cylinder is provided with a valve when the piston is at the top dead center side. Since the structure allows the piston to enter the piston, it not only reduces pressure loss due to flow path resistance and improves self-priming performance and mechanical efficiency, but also reduces the dead volume when the piston reciprocates, The volumetric efficiency of the hydraulic rotary machine can be increased.

Embodiments of the present invention will be described in detail below with reference to FIGS. 3 and 4. In this figure, the same components as in FIGS. 1 and 2 are given the same reference numerals, and their explanations will be omitted.

21 is a cylinder block used in this example;
The cylinder block 21 has a cylinder 2 in the axial direction.
2, 22, .
It is now possible to enter inside. A recess 23 having a diameter D larger than the diameter d of each cylinder 22 is formed in the cylinder block 21 at a position corresponding to the end of each cylinder 22.

On the other hand, the reference numeral 24 designates a pressing plate used in this embodiment. Similar to the pressing plate 7 according to the prior art, the pressing plate 24 has an auxiliary piston portion 25 protruding from one side at a position corresponding to the cylinder 22, and the other side thereof. Although the sliding surface 24A is formed, each auxiliary piston section 25 is different in that it has a larger diameter than the auxiliary piston section 9 according to the prior art and is fitted into the recess 23. An auxiliary piston portion 25 is provided on the pressing plate 24.
An auxiliary cylinder 26 having a diameter larger than the diameter d of the piston 6 is bored through the piston 6, and the auxiliary cylinder 26 opens on the sliding surface 24A of the pressing plate 24. Therefore, the auxiliary cylinder 26 not only functions as the communication passage 10 in the prior art described above, but also allows the piston 6 to enter into the auxiliary cylinder 26 at its top dead center position. It also has the function of forming a part of the cylinder 22.

Furthermore, 27 is a valve plate according to the present embodiment, and one side of the valve plate 27 has a sliding surface 28A that is in sliding contact with the sliding surface 24A of the pressing plate 24, similar to the valve plate 8 according to the prior art.
The other side is connected to the casing 1 by the pin 13.
A suction port 29 and a discharge port 30 are provided as a pair of suction and discharge ports. However, in the valve plate 28 according to this embodiment, the groove width B of the suction port 29 and the discharge port 30 is
The difference is that it is larger than the diameter d of the piston 6.

In the figure, reference numeral 31 denotes a disc spring disposed between the stepped portion 2A formed on the rotating shaft 2 and the stepped portion 24B of the pressing plate 24, and the pressing plate 24 is pressed against the valve plate 28 by the disc spring 27. At the same time, the end surface 2 of the auxiliary piston part 25
A gap δ is formed between the cylinder block 5A and the bottom wall of the recess 23 of the cylinder block 21, on which fluid pressure acts. 32
is a sealing member provided between the auxiliary piston part 25 and the recessed part 23.

The hydraulic rotating machine according to this embodiment has the above-described configuration, and when it is a swash plate type hydraulic pump, its function as a pump is not particularly different from that of the prior art described above.

However, since the press plate 24 is fitted into the recess 23 whose diameter is larger than the diameter d of the cylinder 22, the diameter of the auxiliary piston part 25, together with the disc spring 31, determines the force with which the press plate 24 presses against the valve plate 28. D
can be appropriately increased without being restricted by the diameter d of the cylinder 22. Therefore, the recess 23
As the diameter D of the auxiliary piston part 25 is increased, the pressure receiving area formed on the end surface 25A of the auxiliary piston part 25 increases dramatically, and a larger pressing force can be obtained. As a result, even if the opening force is increased by increasing the groove width B of the suction and exhaust ports 29 and 30 formed in the valve plate 28, fluid is prevented from leaking from between the sliding surfaces 28A and 24A. can do. In this way, by increasing the groove width B of the suction and exhaust ports 29 and 30, the diameter of the auxiliary cylinder 26 can also be increased, so the flow resistance in the auxiliary cylinder 26 is significantly reduced, and pressure loss can be reduced. This not only increases the mechanical efficiency of the pump, but also improves its self-priming ability and prevents cavitation.

Next, since the diameter of the auxiliary cylinder 26 is larger than the diameter of the piston 6, the piston 6 can protrude into the auxiliary cylinder 26. Therefore, the stroke of the piston 6 is not restricted by the auxiliary piston part 25, and the top dead center position is set at the intake/discharge port in the auxiliary cylinder 26.
4 and 15, the stroke S of the piston 6 can be increased, and most of the fluid compressed within the cylinder 22 can be discharged into the discharge port 15. Moreover, the axial dimension of the cylinder block 21 can be shortened.

In addition, in the above-mentioned embodiment, the case where the hydraulic rotating machine according to the present invention is used as a swash plate type hydraulic pump was explained, but it can also be used as a hydraulic motor, and it can also be used as a type having a cylinder block and a valve plate. Of course, it can also be used as a pump or motor of other types, such as a diagonal shaft type.

As described in detail above, according to the hydraulic rotating machine according to the present invention, a recess having a diameter larger than that of each cylinder is formed at a position corresponding to the cylinder bored in the cylinder block, and a pressing plate is provided in the recess. An auxiliary piston part protruding from the cylinder is fitted, an auxiliary cylinder having a diameter larger than the diameter of the piston sliding in the cylinder is bored in the pressing plate, and the piston is made to enter into the auxiliary cylinder, and Since the groove width of the pair of suction/exhaust ports formed in the valve plate is formed larger than the diameter of the piston, the following effects can be achieved.

Since the auxiliary piston part of the pressing plate is fitted into a large diameter recess formed in the cylinder block, the diameter of the auxiliary piston part, which determines the pressing force of the pressing plate against the valve plate, is limited by the diameter of the piston. You can make it bigger without having to worry about it. As a result, it is possible to obtain sufficient pressing force against the valve plate.
Even if the opening force is increased by increasing the groove width of the suction/exhaust port of the valve plate, leakage of fluid can be prevented at the sliding surface between the valve plate and the pressing plate.

In relation to the above item, since the groove width of the pair of suction/exhaust ports bored in the valve plate is formed to be larger than the diameter of the piston, the diameter of the auxiliary cylinder that communicates between the suction/exhaust ports and each cylinder can also be increased. , pressure loss due to flow path resistance can be reduced. Thereby, it is possible to improve the mechanical efficiency of the hydraulic rotating machine, and also to improve the self-priming ability when used as a pump, and to prevent the occurrence of cavitation.

Since the diameter of the auxiliary cylinder is larger than the diameter of the piston, the piston can be inserted into the auxiliary cylinder, which significantly reduces the dead volume at the end of the stroke and improves the volumetric efficiency of the hydraulic rotating machine. This results in extremely good volumetric efficiency, especially during high-pressure operation.

As a result of the above, the top dead center of the piston can be set near the opening to the suction/exhaust port in the auxiliary cylinder, so the axial dimension of the cylinder block can be shortened and the stroke of the piston can be increased. This allows the hydraulic rotary machine to be shortened in its axial direction, making it possible to downsize the entire device.

[Brief explanation of drawings]

FIG. 1 is a partial vertical cross-sectional view of a hydraulic rotating machine according to the prior art, FIG. 2 is a cross-sectional view in the direction of the − arrow in FIG.
FIG. 3 is a partial vertical cross-sectional view of a hydraulic rotary machine according to an embodiment of the present invention, and FIG. 4 is a cross-sectional view in the direction indicated by the - arrow in FIG. 3. 2... Rotating shaft, 6... Piston, 21... Cylinder block, 22... Cylinder, 23... Recess, 24... Pressing plate, 25... Auxiliary piston part, 2
6... Auxiliary cylinder, 28... Valve plate, 29, 30
...Suction/exhaust port.

Claims (1)

[Claims] 1. A rotating shaft rotatably supported by a casing, a cylinder block disposed within the casing to rotate together with the rotating shaft, and a plurality of cylinders bored in the axial direction of the cylinder block. , a plurality of pistons provided reciprocally in each of the cylinders, and a plurality of recesses formed in positions corresponding to each of the cylinders on the end side of the cylinder block and having a diameter larger than that of each of the cylinders; A pressing plate provided at the end of the cylinder block and having a plurality of auxiliary pistons formed on one side thereof to fit into the respective recesses, and each auxiliary piston of the pressing plate communicating with each of the cylinders. a plurality of auxiliary cylinders that are bored in the axial direction with a diameter larger than the diameter of the piston at the position of the piston and that can enter when the piston reaches the top dead center side; and the other surface of the press plate. A valve plate is provided on the side, and a hole is formed in the valve plate so as to communicate intermittently with each of the auxiliary cylinders while the cylinder block and the pressing plate rotate together, and the piston A hydraulic rotary machine consisting of a pair of suction/exhaust ports having a groove width larger than the diameter of the hydraulic rotating machine.