JPH04259674A - Liquid pressure rotary machine with swash plate - Google Patents

Abstract

PURPOSE:To provide a bearing force to be, which is applied to a cylinder block by each static pressure pocket, as mating with the force corresponding to the pressure of an oil liquid on high pressure side by forming an oil path for the oil liquid led from the high pressure side cylinders to the static pressure pockets in the cylinder block and casing, and thereby shortening the oil path. CONSTITUTION:A cylinder block 22 is provided with a communication hole 24 leading from each cylinder 23 and located in the neighborhood of a valve plate 9. The casing body 21A is furnished with an arc-shaped groove 25 constituting the high pressure side, communication hole 26, No.1 static pressure pocket 27, and No.2 static pressure pocket 28. This permits shortening of the oil path length for the oil liquid introduced from each cylinder 23 on high pressure side to the static pressure pockets 27, 28.

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 hydraulic rotating machine used in a swash plate type hydraulic pump, motor, etc.

0002

2. Description of the Related Art A fixed capacity swash plate type hydraulic pump will be described as an example of a swash plate type hydraulic rotary machine according to the prior art with reference to FIGS. 5 to 9.

[0003] In the figure, 1 indicates a casing, and the casing 1 is composed of a casing main body 1A formed in the shape of a cylinder with a bottom, and a lid portion 1B for covering an opening. Also,
A rotating shaft 2 rotated by a drive source such as an engine is inserted into the casing body 1A from the outside, and the rotating shaft 2 is supported by a bearing (not shown). 3
indicates a cylinder block fitted to the inner circumferential surface of the casing body 1A, and the cylinder block 3 is connected to the rotating shaft 2 by a spline joint 4 so as to be rotated in synchronization with the rotating shaft 2. It has become. and,
A plurality of cylinders 5, 5, . Each cylinder 5 opens toward one end surface of the cylinder block 3 (towards the right in the figure). Further, a piston 6 is fitted into each cylinder 5 so as to be able to reciprocate.
A spherical portion 6A is formed at the tip. A shoe 7 as a sliding member is swingably attached to each spherical portion 6A.

Reference numeral 8 indicates a swash plate, and the surface of the swash plate 8 facing the cylinder block 3 serves as a shoe guide plate 8A as an inclined surface on which the shoe 7 slides.
A is inclined with respect to the rotation axis 2. Reference numeral 9 indicates a valve plate that is fixed to the inner surface of the lid portion 1A of the casing 1 and comes into sliding contact with the other end surface of the cylinder block 3. A pair of semicircular arc-shaped supply and discharge ports 9A and 9B are bored in the valve plate 9. The cylinder 5 is rotated according to the rotation of the cylinder block 3.
is connected to each supply/discharge port 9A, 9 via the cylinder port 5A.
It is configured to communicate with B intermittently. Further, the lid portion 1B of the casing 1 is provided with supply and discharge passages 10A and 10B that are constantly in communication with the supply and discharge ports 9A and 9B.

Furthermore, static pressure pockets 11 and 12 are provided on the inner surface of the casing body 1A by forming arc-shaped recesses at different positions in the axial direction of the cylinder block 3, and each of the static pressure pockets 11 and 12 It opens toward the outer peripheral surface of the cylinder block 3.

[0006] Here, one static pressure pocket 11 is connected to the swash plate 8.
It is arranged so as to extend on both sides in the circumferential direction with the bottom dead center position of the piston 6 as the center. Further, the other static pressure pocket 12 is arranged at a position close to the valve plate 9 so as to extend to both ends in the circumferential direction centering on the top dead center position of the piston 6, and its opening area is larger than that of the static pressure pocket 11. is also smaller.

Each of the static pressure pockets 11 and 12 is provided with an oil passage 13A located outside the casing 1.
, 13B are open, and the respective oil passages 13A, 13B are merged in the middle to form an oil passage 13, and the oil passage 13 communicates with the high pressure side passage of the supply/discharge passages 10A, 10B. Here, when the hydraulic rotary machine is used as a hydraulic pump, the high-pressure side passage is specified, so the oil passage 13 may be communicated with this high-pressure side passage. However, when used as a hydraulic motor capable of forward and reverse rotation, the high pressure side passage is different for forward and reverse rotation, so as shown in FIG.
is the supply/discharge passage 10A via the check valves 14A, 14B,
Just connect it to 10B.

Furthermore, as shown in FIGS. 6 and 7, a plurality of divided dynamic pressure pads 15, 15, .
On the other hand, dynamic pressure pads 16, 16, . . . are also formed at portions extending in the circumferential direction of the static pressure pocket 12. Further, a lubricating oil film is formed between each of the dynamic pressure pads 15 and 16 and the outer peripheral surface of the cylinder block 3. In this state, the cylinder block 3 rotates while sliding on the lubricating oil film while entraining hydraulic oil as oil into the gap between the dynamic pressure pads 15 and 16.

The hydraulic pump according to the prior art has the above-mentioned structure, and its operation will be explained next. First, the rotating shaft 2 is connected to a drive source such as an engine, and when the rotating shaft 2 is rotationally driven, the cylinder block 3 rotates in synchronization with this. Here, a piston 6 is provided in each cylinder 5 of the cylinder block 3, and a shoe 7 attached to the tip of the piston 6 is attached to a shoe guide plate 8 of the swash plate 8.
Since the shoe 7 is in contact with the shoe guide plate 8A, when the cylinder block 3 rotates, the shoe 7 slides on the shoe guide plate 8A.

However, since the shoe guide plate 8A is inclined with respect to the rotating shaft 2, the piston 6 reciprocates within the cylinder 5 as the shoe 7 slides on the shoe guide plate 8A. Then, the piston 6 is in the cylinder 5
During the half rotation extending from the piston 6, that is, while the piston 6 moves from the top dead center to the bottom dead center, the cylinder port 5A communicates with the supply port among the supply and discharge ports 9A and 9B bored in the valve plate 9, Hydraulic oil is supplied into the cylinder 5. On the other hand, during a half-turn when the piston 6 enters the cylinder 5, that is, while the piston 6 moves from the bottom dead center to the top dead center, the cylinder port 5A communicates with the discharge port and pressurizes the hydraulic oil to a high pressure. A pumping action is performed by discharging oil from the discharge port.

By the way, during the discharge stroke of the pump, the hydraulic oil in the cylinder 6 is at high pressure, and this high pressure oil causes a hydraulic reaction force to act on the piston 6. Since the swash plate 8 supports the piston 6 in an inclined state through the shoes 7, the cylinder block 3 receives a load in the radial direction. Then, this radial direction load is applied to a resultant force F (Fig. 5 and FIG. 9), and this resultant force F acts in a direction to rotate the cylinder block 3 parallel to the swash plate 8, that is, toward the bottom dead center position of the piston 6.

However, in the static pressure pockets 11 and 12, the pressure in the high pressure side passage of the high pressure supply and discharge passages 10A and 10B acts on the cylinder block 3. The pressure inside 12 functions as a hydrostatic bearing, and supporting forces in the X direction and Y direction shown in FIG. 9 act on the cylinder block 3, respectively. This results in
The cylinder block 3 rotates while being stably supported within the casing 1. The force acting on the cylinder block 3 changes depending on the pressure of the hydraulic rotating machine, but the supporting force due to each hydrostatic bearing also changes depending on the pressure.
The balance of power is extremely good.

[0013]Although high pressure oil leaks into the casing 1 from the static pressure pockets 11 and 12, the inside of the casing 1 is communicated with a tank through a drain pipe (not shown). No pressure builds up. In addition, for example, when irregular external forces act on the rotating shaft 2 due to vibrations of a power source such as an engine, even when the static pressure bearings formed by the static pressure pockets 11 and 12 cannot sufficiently absorb it. Since this can be absorbed by the dynamic pressure pads 15 and 16, the operation of the hydraulic rotating machine is extremely stable.

[0014]

By the way, in the above-mentioned prior art, high-pressure oil is statically discharged from either one of the supply and discharge passages 10A and 10B provided in the lid portion 1B of the casing 1 through the oil passage 13 disposed externally. Since the pressure is guided to the pressure pockets 11 and 12, the pressure generated in each cylinder 5 is generated in the static pressure pockets 11 and 12 with a momentary delay due to the influence of the flow path length required for pressure transmission. As a result, when the pressure inside each cylinder 5 changes continuously, the balance between the radial resultant force F and the supporting forces X and Y shown in FIG. 9 is lost, the accuracy as a hydrostatic bearing deteriorates, and the cylinder block 3 begins to rotate at an angle with respect to the rotation axis 2, and the cylinder block 3 comes to rotate by sliding on each dynamic pressure pad 15, 16, and this sliding resistance becomes rotational resistance, and the rotation There is a problem in that it interferes with the operation of the machine.

[0015] Also, the pressure oil on the high pressure side is transferred to the static pressure pocket 11,
12, an oil passage 13 and check valves 14A and 14B are provided externally, but for this reason,
It is necessary to provide a sealing member or the like at the connection site, which increases the number of parts and reduces reliability.

The present invention was developed in view of the problems of the prior art described above, and the present invention not only simplifies the configuration of the oil passage that introduces high-pressure oil into the static pressure pocket, but also reduces the pressure in the static pressure pocket by reducing the pressure of the high-pressure oil. It is an object of the present invention to provide a swash plate type hydraulic rotating machine that suppresses rotational resistance of a cylinder block by quickly responding to pressure fluctuations.

[0017]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the feature of the structure adopted by the present invention is that the cylinder block is located near the valve plate, and is arranged in the radial direction of the cylinder block for each cylinder. A communication hole is bored outward, and the casing is formed with a communication path that constantly communicates with at least one of the communication holes of each cylinder on the high pressure side, and the communication path is formed on the inner peripheral surface of the casing. At least one static pressure pocket communicating with the cylinder block and opening toward the outer peripheral surface of the cylinder block is provided.

[0018]

[Operation] With the above configuration, high pressure oil can be directly introduced from the cylinder on the high pressure side into the static pressure pocket through the communication hole and passage, and the pressure generated in the static pressure pocket is almost the same as the pressure on the high pressure side. At one time, the same pressure can be set.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to FIGS. 1 to 4, taking a swash plate type hydraulic pump as an example. In the embodiment, the same components as those in the prior art described above are given the same reference numerals, and their explanations will be omitted.

In the figure, reference numeral 21 indicates a casing according to the present embodiment, and the casing 21 is constructed almost in the same way as the casing 1 of the prior art, and includes a casing body 21A formed in a cylindrical shape with a bottom; Lid part 2 to be closed
It consists of 1B. Then, the casing body 21
Inside A are a rotating shaft 2, a cylinder block 22 (described later) that is fitted to the inner circumferential surface of the casing body 21A and attached to the rotating shaft 2 via a spline joint 4, and one part of the cylinder block 22. Pistons 6, 6, ... are inserted into each cylinder 23 from the end surface so as to be able to move back and forth, and a shoe as a sliding member is provided on a spherical part 6A formed on the tip side of the piston 6 so as to be able to swing freely. 7, 7, ... and a swash plate 8 having a shoe guide plate 8A that guides and slides each shoe 7.
and a valve plate 9 having a pair of supply/discharge ports 9A and 9B provided on the other end surface of the cylinder block 22.

Reference numeral 22 denotes a cylinder block fitted to the inner circumferential surface of the casing body 21A, and the cylinder block 22 is connected to the rotating shaft 2 through a spline joint 4, and rotates in synchronization with the rotating shaft 2. It is designed to be rotated. Further, a plurality of holes (for example, an odd number of holes such as 5 holes, 7 holes, etc.) are formed in the cylinder block 22 from one end surface at predetermined intervals in the circumferential direction and parallel to the axis B-B of the rotating shaft 2.
In addition to the cylinders 23, 23, . Communication holes 24, 24, . . . that communicate with each other are provided.

Reference numeral 25 indicates an arcuate groove formed on the inner circumferential surface of the casing body 21A, and the arcuate groove 25 is located at a position in the axial direction corresponding to each communication hole 24 of the cylinder block 22. 2, it corresponds to each cylinder 23 on the discharge side (the section where the piston 6 in the cylinder 23 moves from the bottom dead center to the top dead center), and is approximately 180 degrees with respect to the rotation center of the rotating shaft 2. It is formed with an opening angle of 170 degrees, for example, and the arcuate groove 25 and each cylinder 23 on the discharge side are always in communication via the communication hole 24 .

Reference numeral 26 indicates a communication hole formed in the axial direction in the casing body 21A, one end of the communication hole 26 is connected to the arcuate groove 25, and the other end is connected to the first static pressure pocket 27, which will be described later. They are communicated via connection holes 26A and 26B. The communication hole 26 and the arcuate groove 25
A communication path is formed.

Reference numeral 27 indicates a first static pressure pocket formed in an arc shape on the inner peripheral surface of the casing body 21A, and the first static pressure pocket 27 opens toward the outer peripheral surface of the cylinder block 22, At a position in the axial direction corresponding to one end side of the cylinder block 22, and as shown in FIG. It has a concave shape with a cross section that is shallower and wider than the arcuate groove 25. The first static pressure pocket 27 communicates with the communication hole 26 via the connection hole 26B.

Reference numeral 28 indicates a second static pressure pocket formed in an arc shape on the inner peripheral surface of the casing body 21A, and the second static pressure pocket 28 opens toward the outer peripheral surface of the cylinder block 22. An axial position adjacent to one side of the arcuate groove 25, and as shown in FIGS. 2 and 4, the top dead center of the piston 6 is at the center and approximately relative to the rotation center of the rotating shaft 2. It has an opening angle of 90 degrees and is formed into a concave shape with a cross section that is shallower and wider than the arcuate groove 25 . The second static pressure pocket 28 communicates with the arcuate groove 25 through an arcuate opening 28A.

Note that 29 is the lid portion 21B of the casing 21.
It shows the discharge passage of a pair of supply and discharge passages drilled in the
The discharge passage 29 is connected to the high pressure side port 9A (hereinafter referred to as "
The cylinder 2 on the discharge side via the discharge port 9A")
3 and discharges high pressure oil.

The swash plate type hydraulic pump according to this embodiment has the above-described configuration, and its basic operation is not particularly different from that of the prior art.

However, in this embodiment, the cylinder block 22 is provided with a communication hole 24 formed from each cylinder 23 outward in the radial direction of the cylinder block 22, and the casing body 21A is provided with a communication hole 24 formed from each cylinder 23 on the discharge side. Communication hole 2
4, and a communication hole 26 extending in the axial direction of the casing body 21A are formed. However, the cylinder block 22 is configured to have a first static pressure pocket 27 and a second static pressure pocket 28 that are open toward the outer circumferential surface of the cylinder block 22.

Therefore, by rotating the cylinder block 22, the high pressure oil in each cylinder 23 on the discharge side is transferred to each cylinder port 23A, discharge port 9A and discharge passage 29.
The high pressure oil is discharged through the cylinder 2 on the discharge side.
3 is supplied from the communication hole 24 to the first static pressure pocket 27 via the arcuate groove 25 and the communication hole 26, and is supplied to the second static pressure pocket 27 via the arcuate groove 25 and the arcuate opening 28A. is supplied to the static pressure pocket 28.

As a result, pressure from high pressure oil can be directly applied to the outer circumferential surface of the cylinder block 22 in each of the static pressure pockets 27 and 28, and as shown in FIG. Empower. That is, in the static pressure pockets 27 and 28, the pressure in the discharge port 9A acts on the cylinder block 22, and the static pressure pockets 27 and 28
, 28 function as a static pressure bearing, and support forces in the X and Y directions shown in FIG. 9 act on the cylinder block 3, respectively. Therefore, the cylinder block 22 can be stably supported within the casing body 21A against the resultant force F of the radial load due to the hydraulic reaction force, and the cylinder block 23 can be smoothly rotated within the casing body 21A.

Thus, in this embodiment, a portion of the high-pressure oil discharged from the cylinder 23 located on the discharge side is channeled through the communication holes 24 formed in the cylinder block 22 and the arc-shaped groove formed in the casing body 21A. 25 and communication hole 2
6 etc. into each static pressure pocket 27, 28, and the pressure in each static pressure pocket 27, 28 is directly set by this high pressure oil. It is possible to omit the oil passage 13 consisting of an external pipe for drawing out the oil, a seal member, etc., and the number of parts can be reduced, thereby making it possible to reliably reduce costs.

Further, the high pressure oil to be discharged can be introduced into the first static pressure pocket 27 from the circular arc groove 25 through the communication hole 26, and into the second pocket 28 through the circular arc groove 2.
5 through the arcuate opening 28A,
The distance of the oil passage between each cylinder 23 on the discharge side and each static pressure pocket 27, 28 can be reliably shortened. Therefore, the pressure in the static pressure pockets 27, 28 can be immediately made equal to the pressure corresponding to the fluctuation of the high pressure oil introduced from each cylinder 23 on the discharge side, and the pressure can be easily transmitted to each of the static pressure pockets 27, 28. Less time is required, and each static pressure pocket 27
, 28 are the radial support forces X, Y corresponding to the resultant force F.
This effectively prevents contact between the outer circumferential surface of the cylinder block 23 and the inner circumferential surface of the casing body 21A, reliably prevents an increase in rotational resistance, and improves pump efficiency.

[0033] In the above embodiment, the case where a swash plate type hydraulic pump is used as the swash plate type hydraulic rotary machine has been explained as an example, but the present invention is not limited to the swash plate type hydraulic pump.
It may also be used in a swash plate type hydraulic motor or the like. On the other hand, it may be a variable capacity hydraulic rotary machine in which the tilting angle of the swash plate is variable.

Further, in the above embodiment, the arcuate groove 25 constituting the communication path is approximately 18 mm away from the center of rotation of the rotating shaft 2.
Although the case where the opening angle is 0 degrees has been described, the present invention is not limited to this, and the opening angle may be made small.

Furthermore, in the embodiment, two static pressure pockets 2
7 and 28, but it is also possible to configure the structure with only one static pressure pocket. In this case, the static pressure pocket is designed to support the cylinder block 22 with a support force that balances the resultant force F. The opening angle may be increased.

Furthermore, each communication hole 24 bored in the cylinder block 22 was provided adjacent to the cylinder port 23A of each cylinder 23, but the communication hole 24 was bored at the position of each cylinder port 23A. , and the outer peripheral surface of the cylinder block 22 may be configured to communicate with each other.

[0037]

As described in detail above, according to the present invention, the cylinder block is provided with a communication hole located near the valve plate and communicating with each cylinder, which is bored outward in the radial direction of the cylinder block. , the casing main body is formed with a communication passage that constantly communicates with at least one of the communication holes of each of the cylinders on the high pressure side, and the inner circumferential surface of the casing is formed with a communication passage that communicates with the communication passage, Since the structure has at least one static pressure pocket that opens toward the outer circumferential surface, the static pressure pockets can be immediately set to the same pressure by the pressure of the oil introduced from each cylinder, and the bearing force can be increased without delay. can be generated, and the rotation of the cylinder block can be made smooth. Further, since communication holes and communication paths for introducing oil into the static pressure pockets are provided in the casing and cylinder block, the number of parts can be reduced compared to the prior art, and costs can be reduced. Furthermore, since the distance of the oil passage that introduces the oil into the static pressure pocket can be shortened, the pressure inside the static pressure pocket can quickly respond to fluctuations in pressure on the high pressure side, allowing high-precision static pressure A bearing can be configured.

[Brief explanation of the drawing]

FIG. 1 is a sectional view taken in the direction of arrow I-I in FIG. 2, showing a swash plate type hydraulic pump according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along II-II in FIG. 1;

FIG. 3 is a sectional view taken along the line III-III in FIG. 1; .

FIG. 4 is a sectional view taken along IV-IV in FIG. 1;

FIG. 5 is a longitudinal sectional view of a swash plate type hydraulic pump according to the prior art.

6 is a sectional view taken along arrow VI-VI in FIG. 5. FIG.

FIG. 7 is a sectional view taken along arrow VII-VII in FIG. 5;

FIG. 8 is a circuit diagram showing a connection state between an oil passage and a supply/discharge passage.

FIG. 9 is an explanatory diagram of loads acting on the cylinder block.

[Explanation of symbols]

2 Rotation axis 6 Piston 7 Shoe (sliding member) 8 Swash plate 8A Shoe guide plate (swash plate) 9 Valve plate 21 Casing 21A Casing body 22 Cylinder block 23 Cylinder 24 Communication hole 25 Arc-shaped groove 26 Communication hole 27 First static pressure pocket 28 Second static pressure pocket

Claims (1)

[Claims] 1. A cylindrical casing, a rotating shaft provided on the casing, and a rotary shaft that is attached to the rotating shaft with an outer circumferential surface fitted to an inner circumferential surface of the casing, and spaced apart at a predetermined interval in the circumferential direction. A cylinder block in which a plurality of cylinders are bored in the axial direction, a piston that is inserted into each cylinder from one end surface of the cylinder block so as to be able to reciprocate, and a side of each piston that protrudes from the cylinder block. a plurality of sliding members swingably attached to an end, a swash plate facing the cylinder block and having an inclined surface on which each sliding member slides, and slidingly contacting the other end surface of the cylinder block; In the swash plate type hydraulic rotating machine, the cylinder block includes a valve plate having a supply/discharge port for supplying and discharging oil into the cylinder, and the cylinder block has a cylinder block located near the valve plate for each cylinder. A communication hole is bored radially outward in the casing, a communication path is formed in the casing that constantly communicates with at least one of the communication holes of each cylinder on the high pressure side, and a communication path is formed in the inner circumferential surface of the casing. A swash plate type hydraulic rotating machine, characterized in that at least one static pressure pocket is provided that communicates with the communication passage and opens toward the outer peripheral surface of the cylinder block.