JP2005220789A - Swash plate type fluid compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a swash plate type fluid compressor for suppressing the leakage of operating fluid from between a cylinder block and a valve plate particularly when a mouth is open on a high pressure side. <P>SOLUTION: The swash plate type fluid compressor comprises the cylinder block 5 rotatably provided, a piston 6 reciprocatively provided in the cylinder block with a piston shoe 7 at one end, a swash plate part 8 on which the piston shoe slides, and the valve plate 9A having a low pressure port 16A to be a relatively low pressure fluid flow path and a high pressure port 17A to be a relatively high pressure fluid flow path for sliding together with the cylinder block to seal fluid in the cylinder block with a seal surface 90A. The sealing surface of the valve plate on the high pressure port side is set to be lower than on the low pressure port side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a swash plate type fluid pressure device used as a pump or a motor, and in particular, even when a fluid having a low viscosity such as water is used as a working fluid, the sealing performance may deteriorate. There is no swash plate type fluid pressure equipment.

  FIG. 7 is a cross-sectional view showing a configuration of a swash plate type axial piston pump which is an example of a conventional swash plate type fluid pressure device. In FIG. 7, reference numeral 1 denotes a casing, 2 denotes an end plate, 3 denotes a grade, 4 Is a rotating shaft, 5 is a cylinder block, 6 is a piston, 7 is a piston shoe, 8 is a swash plate, and 9 is a valve plate.

  The end plate 2 is mounted on one end of the casing 1 and the gradle 3 is mounted on the other end of the end plate 2, and a rotary shaft 4 is rotatably supported by a bearing 11 provided individually at the center thereof. Has been. The end plate 2 is provided with a suction port 12 and a discharge port 13 that form a water inlet / outlet of the working fluid. A space surrounded by the casing 1, the end plate 2, and the grade 3 is used as a working fluid chamber 15.

  One end of the rotating shaft 4 passes through the grade 3 and is connected to an external driving device such as a motor or a prime mover (not shown). A metal cylinder block 5 fitted with a plurality of pistons 6 is attached so as to be spline-engaged with the rotating shaft 4 in the working fluid chamber 15 and rotated together with the shaft 4. The swash plate 8 is supported by the gradle 3 and is built in the working fluid chamber 15 so as to obliquely intersect the axis of the rotary shaft 4. The swash plate 8 has an annular thrust plate 14. Installed. The piston shoe 7 of each piston 6 is slid on the plate 14.

  The valve plate 9 is fixed to the end plate 2 and is sandwiched between the plate 2 and the cylinder block 5. The valve plate 9 on which the cylinder block 5 slides is formed entirely of stainless steel, and has a low pressure port 16 communicating with the suction port 12 and a high pressure port 17 communicating with the discharge port 13.

  The swash plate type axial piston pump having such a configuration can perform a pump operation by driving the rotating shaft 4. That is, when the rotary shaft 4 is driven, the piston shoe 7 slides on the thrust plate 14 of the swash plate 8 as the cylinder block 5 rotates together with the shaft 4, and the piston 6 and the swash plate 8. At the same time, the cylinder block 5 slides on the valve plate 9.

  Therefore, since the piston 6 is moved in the axial direction according to the inclination angle of the swash plate 8, water as a working fluid is sucked into the cylinder block 5 from the suction port 12 through the low pressure port 16 of the valve plate 9. Rarely, the water sucked in this way is compressed and discharged as high-pressure water from the discharge port 13 through the high-pressure port 17 of the valve plate 9.

  In the above pump configuration, after changing the shape of the valve plate 9, the pressurized water is caused to pass through the hydraulic fluid inlets 12, 13 in the opposite direction to cause the rotary shaft 4 to generate a rotational motion by the pressurized water. It can also be used as a swash plate type axial piston motor that performs work.

  A valve plate 9 is sandwiched between the cylinder block 5 and the end plate 2, and the valve plate 9 is fixed to the end plate 2. The valve plate 9 is a disc having the same diameter as the maximum outer diameter of the cylinder block 5. The configuration of the valve plate 9 will be described with reference to FIGS.

  8 is a cross-sectional view taken along line AA in FIG. 9 is a cross-sectional view taken along line BB in FIG. FIG. 8 shows a sliding surface 90 of the valve plate 9 with the cylinder block 5. As shown in FIGS. 8 and 9, the valve plate 9 includes a low pressure port 16 that is located on a line drawn with the same radius from the center and continues in an arc shape, and a plurality of high pressure ports that are arranged in an arc shape. Ports 17 are provided penetrating in the thickness direction.

  As shown in FIG. 7, the valve plate 9 has its low pressure port 16 continuous with the opening on the working fluid chamber 15 side of the suction port 12, and the high pressure port 17 on the opening of the discharge port 13 on the working fluid chamber 15 side. It is continuously fixed to the end plate 2. The ports 16 and 17 communicate with the inlet / outlet 5b of each cylinder chamber 5a as the cylinder block 5 rotates.

  A pin hole (not shown) is provided in the outer peripheral portion of the valve plate 9 so as to penetrate in the thickness direction, and a positioning pin (not shown) provided in the end plate 2 is fitted into the pin hole. . By the fitting, movement of the valve plate 9 due to sliding friction with the cylinder block 5 or the like is suppressed, and displacement of the hole position relative to the cylinder block 5 can be prevented.

  8 and 9, reference numeral 91 denotes an inner peripheral seal land formed on the surface of the valve plate 9, reference numeral 92 denotes an outer peripheral seal land, and reference numeral 93 denotes an intermediate seal land. Both ports 16 and 17 are disposed in a region where an intermediate seal land 93 between the inner and outer seal lands 91 and 92 is provided. These seal lands 91 to 93 function as seal surfaces that prevent leakage of working fluid from between the valve plate 9 and the cylinder block 5 that slides on the valve plate 9. As shown in FIG. 9, the inner and outer seal lands 91 and 92 are set to the same height (flat), and further, the intermediate seal land 93 is also set to the same height.

  Liquid leakage in the swash plate type fluid pressure device is likely to occur particularly on the contact (sliding) surface between the valve plate 9 and the cylinder block 5 on which high pressure acts. For this reason, the cylinder block 5 is strongly pressed against the valve plate 9 to minimize the gap at the contact surface.

JP-A-9-209918

The volumetric efficiency of the swash plate type fluid pressure device decreases as the liquid leakage from the sliding portion increases. In other words, the performance of the swash plate type fluid pressure device greatly depends on the sealing performance of the working fluid. The leakage flow rate of a swash plate type fluid pressure device is expressed by the following general formula.
Q = [(h ³ × P) / μ] × K

  In the above general formula, Q is the leakage flow rate, h is the gap, P is the pressure, K is a constant, and μ is the viscosity of the working fluid. From this general formula, it can be seen that the leakage amount Q increases when the pressure P is high and the gap h is large.

  Here, in particular, when the valve plate and the cylinder block are relatively opened (opening) on the high-pressure port side for some reason, the leakage flow rate increases, and the performance of the swash plate type fluid pressure device increases. Incurs a decline.

  In particular, when a fluid with a low viscosity μ, such as water, is used as the working fluid, the amount of water leakage increases even for a slight gap in the sliding part, leading to a decrease in performance. End up.

  An object of the present invention is to provide a swash plate type fluid pressure device capable of suppressing leakage of working fluid from between a cylinder block and a valve plate, particularly when an opening is generated on the high pressure side. .

  A swash plate type fluid pressure device according to the present invention includes a cylinder block that is rotatably provided, a piston that is reciprocally provided in the cylinder block and having a piston shoe at one end, and a swash plate portion on which the piston shoe slides. And a low-pressure port serving as a flow path for relatively low-pressure fluid and a high-pressure port serving as a flow path for relatively high-pressure fluid, and slides on the cylinder block to seal the fluid in the cylinder block. A swash plate type fluid pressure device having a valve plate for sealing at a surface, wherein the height of the outer peripheral seal land on the high pressure port side is set lower than that on the low pressure port side on the seal surface of the valve plate. It is characterized by being.

  In the present invention, the height of the high pressure port side outer peripheral seal land on the seal surface of the valve plate is set lower than that of the low pressure port side. The clearance between the block and the block is originally relatively large. For some reason, when the cylinder block opens on the high pressure port side of the seal surface of the valve plate, the leakage flow rate increases momentarily (temporarily). Since the clearance of the side seal land is larger than that of the high-pressure port side seal land, it is possible to suppress the generation of pressure on the valve plate and the outer peripheral side without preventing the leaked fluid from being discharged out of the valve plate.

  Furthermore, in the present invention, since the height on the low pressure port side of the seal surface of the valve plate is set higher than that on the high pressure port side, the gap with the cylinder block is set small even during normal times. In this case, when the high pressure port side of the sealing surface of the valve plate and the cylinder block are opened for some reason, the clearance between the low pressure port side of the sealing surface of the valve plate and the cylinder block becomes relatively smaller. Lean on. Then, the pressure of the working fluid between the low pressure port side and the cylinder block rises on the seal surface of the valve plate, and a reaction force in the direction of closing the high pressure port side is generated on the seal surface of the valve plate, and a large moment is generated. . As a result, the opening on the high pressure port side on the seal surface of the valve plate is eliminated, and the leakage flow rate on the high pressure side is suppressed. From the above, the sealing performance is improved and the efficiency is increased.

  In the swash plate type fluid pressure device of the present invention, the height of the low-pressure port side on the seal surface of the valve plate is set higher on the downstream side in the rotational direction than on the upstream side in the rotational direction of the cylinder block. It is characterized by being. Here, on the low pressure port side of the seal surface of the valve plate, the configuration in which the height on the downstream side is set higher than the height on the upstream side in the rotation direction of the cylinder block can be a taper or a step.

In the present invention, on the low pressure port side of the sealing surface of the valve plate, where the height on the downstream side is set higher than the height on the upstream side in the rotation direction of the cylinder block, the valve plate Since the pressure of the working fluid between the low pressure port side of the seal surface and the cylinder block rises and a large reaction force is generated in the direction of closing the high pressure port side of the valve plate seal surface, a large moment is generated, Opening on the high pressure port side of the sealing surface of the valve plate is eliminated.
In addition, when the working fluid is water, water has a low viscosity and is inferior in lubrication performance on the friction surface, so seizure and wear on the friction surface become a problem. By setting the height of the downstream side of the low pressure port side of the sealing surface higher than the height of the upstream side of the rotation direction of the cylinder block, the generated pressure increases, which is effective in preventing seizure.

  A swash plate type fluid pressure device according to the present invention includes a cylinder block that is rotatably provided, a piston that is reciprocally provided in the cylinder block and having a piston shoe at one end, and a swash plate portion on which the piston shoe slides. And a low-pressure port serving as a flow path for relatively low-pressure fluid and a high-pressure port serving as a flow path for relatively high-pressure fluid, and slides on the cylinder block to seal the fluid in the cylinder block. A swash plate type fluid pressure device provided with a valve plate that seals on the surface, wherein the high pressure port side of the sealing surface of the valve plate is set to have a lower height toward the radially outer side. It is said.

  In the present invention, since the high pressure port side of the seal surface of the valve plate is set to be lower in the radial direction, when the high pressure port side of the seal surface of the valve plate and the cylinder block are opened, the valve An increase in pressure on the outer peripheral side of the plate seal surface on the high pressure port side is suppressed, thereby eliminating the opening on the high pressure port side of the seal surface of the valve plate.

  A swash plate type fluid pressure device according to the present invention includes a cylinder block that is rotatably provided, a piston that is reciprocally provided in the cylinder block and having a piston shoe at one end, and a swash plate portion on which the piston shoe slides. And a low-pressure port serving as a flow path for relatively low-pressure fluid and a high-pressure port serving as a flow path for relatively high-pressure fluid, and slides on the cylinder block to seal the fluid in the cylinder block. A swash plate type fluid pressure device including a valve plate that seals at a surface, wherein a concave portion communicating in a radial direction is provided along a rotation direction of the cylinder block on the high pressure port side of the sealing surface of the valve plate. It is characterized by being formed in plural.

In the present invention described above, the valve plate having a plurality of radially communicating recesses formed along the rotation direction of the cylinder block during normal operation (when the high-pressure port side of the seal surface of the valve plate is not open). Like the spiral groove type fluid bearing, the high pressure port side outer peripheral seal land has a relatively large working fluid pressure in the narrow gap between the recess and the cylinder block. Great power to support the block. Therefore, seizure is prevented.
On the other hand, when the high-pressure port side of the valve plate seal surface opens, the gap between the recess and the cylinder block widens, so that the drainage of the working fluid on the high-pressure port side of the valve plate seal surface is improved. The pressure of the working fluid in the gap at the high-pressure side seal land portion decreases. As a result, the opening on the high pressure port side of the sealing surface of the valve plate is suppressed. In addition, since the working fluid generated by sliding between the cylinder block and the valve plate is cooled by the working fluid in the other recess, seizure is prevented.

  A swash plate type fluid pressure device according to the present invention includes a cylinder block that is rotatably provided, a piston that is reciprocally provided in the cylinder block and having a piston shoe at one end, and a swash plate portion on which the piston shoe slides. And a low-pressure port serving as a flow path for relatively low-pressure fluid and a high-pressure port serving as a flow path for relatively high-pressure fluid, and slides on the cylinder block to seal the fluid in the cylinder block. A swash plate type fluid pressure device including a valve plate that seals at a surface, wherein the balance of load support capacity of the valve plate is smaller on the high pressure port side than on the low pressure port side on the seal surface. It is configured as described above.

  In the present invention, the ratio of the load support capability of the seal surface on the low pressure port side of the valve plate is relatively large, so that when the gap with the cylinder block is opened on the seal surface on the high pressure port side of the valve plate, The generation of pressure on the high pressure port side seal surface of the valve plate is suppressed, and a large reaction force is generated on the low pressure port side seal surface of the valve plate.

  According to the present invention, when an opening occurs on the high pressure side, the force works so as to eliminate the opening, and the opening is eliminated immediately. Therefore, the working fluid from between the cylinder block and the valve plate is removed. Leakage is suppressed as a result.

  Hereinafter, a swash plate type hydraulic pump in which water is used as a working fluid will be described in detail with reference to the drawings as an embodiment of the swash plate type hydraulic device of the present invention. In addition, about the component which is common in the said prior art, the code | symbol with the same or clear correspondence relationship is attached | subjected, the detailed description is abbreviate | omitted, and it demonstrates centering around the characteristic part of this embodiment.

  With reference to FIGS. 1-1 and 1-2, the swash plate type hydraulic pump of the first embodiment will be described. 1-1 has shown the sliding surface with the cylinder block in the valve plate of the swash plate type hydraulic pump of 1st Embodiment. FIG. 1-2 is a cross-sectional view taken along the line CC of FIG. 1-1.

  1-1 and FIG. 1-2, about the member corresponding to FIG.8 and FIG.9, A is appended to each code | symbol. That is, the valve plate 9A includes a low pressure port 16A that is located on a line drawn with the same radius from the center thereof and that continues in an arc shape, and a plurality of high pressure ports 17A that are arranged in an arc shape in the thickness direction. It is provided to penetrate through. In the sliding surface 90A of the valve plate 9A, reference numeral 91A denotes an inner peripheral seal land formed on the surface of the valve plate 9A, and 93A denotes an intermediate seal land.

  Reference numeral 92AL denotes an outer peripheral seal land (hereinafter referred to as a low-pressure side outer peripheral seal land) provided on the low-pressure port 16A side (hereinafter referred to as a low-pressure side). Similarly, 92AH is a side of the high-pressure port 17A (hereinafter referred to as a low-pressure port 17A). This is an outer peripheral seal land (hereinafter referred to as a high pressure side outer peripheral seal land) provided on the high pressure side.

  Both ports 16A and 17A are arranged in a region where an intermediate seal land 93A between the inner and outer seal lands 91A, 92AL and 92AH is provided. These seal lands 91 </ b> A to 93 </ b> A function as seal surfaces that prevent leakage of working fluid from between the valve plate 9 </ b> A and the cylinder block 5 that slides on the valve plate 9 </ b> A.

  As shown in FIG. 1-2, the high pressure side outer peripheral seal land 92AH is set lower than the low pressure side outer peripheral seal land 92AL. The height difference (step) D is about 10 to several hundred μm. When the viscosity of the working fluid is as low as water, the height difference D is set to be relatively small, and when the viscosity is high like oil, the height difference D is set to be relatively large.

  As in the conventional case shown in FIG. 9, the intermediate seal land 93A and the inner peripheral seal land 91A have the same height (flat), the high pressure side outer peripheral seal land 92AH is lower than the height, and the low pressure side outer peripheral seal land 92AL. Is set high. That is, the high-pressure side outer peripheral seal land 92AH is set lower than before, and the low-pressure side outer peripheral seal land 92AL is set higher than before.

  The height difference D between the low pressure side outer peripheral seal land 92AL and the high pressure side outer peripheral seal land 92AH is appropriately set depending on the scale of the swash plate type hydraulic pump, the size of the valve plate 9A, the rotational speed of the rotary shaft 4, and the like.

  Next, the operation of the first embodiment will be described.

  For some reason, for example, when the rotation of the rotary shaft 4 is shaken, the high pressure side of the valve plate 9 and the cylinder block 5 may be relatively opened (opening). When the height of the high-pressure side outer peripheral seal land 92 is not set to be particularly low as in a conventional swash plate type fluid pressure device, in the normal state (when the opening is not open), the high-pressure side of the valve plate 9 And the cylinder block 5 are relatively smaller than those between the high pressure side outer peripheral seal land 92AH and the cylinder block 5 in the first embodiment. As described above, the conventional high-pressure side outer peripheral seal land 92 has a relatively small gap with the cylinder block 5, and therefore, for some reason, when the high-pressure side of the valve plate 9 and the cylinder block 5 are opened, The pressure of the working fluid increases in a wide area range in the surface direction of the valve plate 9, and the leakage flow rate increases. In this case, if the leakage flow rate is large, the force that pushes the cylinder block 5 due to the pressure of the working fluid increases, and the high pressure side of the valve plate 9 opens with respect to the cylinder block 5 further, and the leakage flow rate further increases.

  Therefore, in the first embodiment, the high pressure side outer peripheral seal land 92AH is set lower than the low pressure side outer peripheral seal land 92AL. Thus, even during normal times, the gap between the high pressure side outer peripheral seal land 92AH and the cylinder block 5 is originally relatively large, and for some reason, when the high pressure side of the valve plate 9A and the cylinder block 5 are opened, Although the leakage flow rate increases temporarily (temporarily), the clearance of the high-pressure port side seal land is larger than that of the high-pressure port side seal land. Pressure generation on the plate and the outer peripheral side can be suppressed.

  In the first embodiment, the low-pressure side outer peripheral seal land 92AL is set higher than the high-pressure side outer peripheral seal land 92AH (and is higher than the conventional flat surface). The gap is set small. In this case, when the high pressure side of the valve plate 9 </ b> A and the cylinder block 5 are opened for some reason, the low pressure side outer peripheral seal land 92 </ b> AL is inclined in a direction in which the gap with the cylinder block 5 becomes relatively smaller. Then, the pressure of the working fluid between the low pressure side outer peripheral seal land 92AL and the cylinder block 5 rises, and a reaction force in the direction of closing the high pressure side of the valve plate 9A is generated, and a large moment is generated. Thereby, the opening on the high pressure side of the valve plate 9A is eliminated, and the leakage flow rate on the high pressure side is suppressed.

  In the present embodiment, the load (pressure) balance of the high-pressure side seal land and the low-pressure side seal land is changed. By relatively increasing the load ratio of the low-pressure side seal land, when the gap between the high-pressure side seal land and the cylinder block 5 is opened, the generation of pressure on the high-pressure side seal land is suppressed. A large reaction force is generated in the seal land on the low pressure side. As means for changing the load (pressure) balance of the high-pressure side seal land and the low-pressure side seal land, the heights of the high-pressure side outer peripheral seal land 92AH and the low-pressure side outer peripheral seal land 92AL are changed.

  From the above, in the swash plate type hydraulic pump using the valve plate 9A of the first embodiment, the sealing performance is improved and the efficiency is increased.

  In the conventional general case, when the gap between the valve plate 9 and the cylinder block 5 opens on the high pressure side, the leakage flow rate increases. As a result, the outer peripheral seal land 92 on the high pressure side becomes a seal and pressure is generated. In contrast, in the first embodiment, the generation of pressure at the high-pressure side outer peripheral seal land 92AH is suppressed by lowering the high-pressure side outer peripheral seal land 92AH from the low-pressure side outer peripheral seal land 92AL. Further, in the low-pressure side outer peripheral seal land 92AL, the gap is extremely small and a large reaction force is generated. Therefore, a large moment is generated, and the effect of eliminating the high-pressure side opening is obtained.

  In the present embodiment, in the high pressure side outer peripheral seal land 92AH and the low pressure side outer peripheral seal land 92AL, the height difference can be given to all of the high pressure side and the low pressure side (three in FIG. 1-1). Alternatively, it may be one each on the high pressure side and the low pressure side (the CC line is drawn in FIG. 1-1) located at the center of the low pressure port 16A and the high pressure port 17A (the following). The same applies to the embodiment).

  In the above description, a height difference is provided in the height of only the outer peripheral seal lands 92AL and 92AH of the valve plate 9A, but a difference in height can also be provided in the inner peripheral seal lands 91A on the high pressure side and the low pressure side. . In this case, the height of each seal land is set higher in the order of the outer peripheral side on the high pressure side, the inner peripheral side on the high pressure side, the inner peripheral side on the low pressure side, and the outer peripheral side on the low pressure side. It can be formed in a tapered shape. In this case, the effect of the moment is largely related to the radius of the point where the force acts (distance from the center point of the valve plate 9A), so there is a difference in height between the high-pressure side and low-pressure side outer peripheral seal lands 92AH and 92AL. Is particularly effective.

  In the first embodiment, the swash plate hydraulic pump that uses water as the working fluid has been described. However, even if the technique of the first embodiment is applied to a swash plate hydraulic pump that uses oil as the working fluid, This is effective in suppressing leakage of working fluid from between the cylinder block and the valve plate. In the first embodiment, the swash plate type hydraulic pump has been described, but it is also effective when used as a swash plate type axial piston motor.

  Next, a swash plate type hydraulic pump according to a second embodiment will be described with reference to FIGS. In the second embodiment, components that are the same as those described above will be given the same or corresponding reference numerals, and detailed descriptions thereof will be omitted, and the description will focus on the features of the present embodiment.

  As shown in FIGS. 2-1 and 2-3, the gap between the single or plural low-pressure side outer peripheral seal lands 92BL and the cylinder block 5 in the circumferential direction according to the rotational direction Y1 of the rotary shaft 4 is provided. A tapered surface 101 is provided which becomes smaller. The taper depth 101d is about 10 to several 100 μm. Other configurations are the same as those in the first embodiment, as shown in FIGS. 2-1 and 2-2.

  According to the second embodiment, the following operation occurs in addition to the first embodiment.

  Since the low pressure side outer peripheral seal land 92BL is set higher than the high pressure side outer peripheral seal land 92BH (and is higher than the conventional flat surface), the high pressure side of the valve plate 9B and the cylinder block 5 are opened for some reason. In this case, the gap between the low-pressure side outer peripheral seal land 92BL and the cylinder block 5 is further reduced, and the low-pressure side outer peripheral seal land 92BL formed with the tapered surface 101 has a taper wedge effect due to the taper wedge effect. Since the pressure of the working fluid between the land 92BL and the cylinder block 5 further increases and a large reaction force is generated in the direction of closing the high pressure side of the valve plate 9B, a large moment is generated, and the opening on the high pressure side is opened. The effect to be eliminated is obtained.

  In the swash plate hydraulic pump, the friction surface is lubricated with water, which is the working fluid, but water has low viscosity and inferior lubrication performance on the friction surface, so seizure and wear on the friction surface are problems. Become. In the second embodiment, providing the tapered surface 101 increases the generated pressure, which is effective in preventing seizure.

  The tapered surface 101 can be provided not only on the low-pressure side outer peripheral seal land 92BL but also on the low-pressure side inner peripheral seal land.

  In the above description, the taper surface 101 is formed only on the low-pressure side seal land, but not on the high-pressure side seal land. On the other hand, the tapered surface 101 can be formed on both the low-pressure side and the high-pressure side seal land. However, when the taper is provided on both the high-pressure side and the low-pressure side in this way, the low-pressure side seal land is relatively The taper angle (taper depth) is set such that a large pressure (load) is generated.

  Next, a swash plate type hydraulic pump according to a third embodiment will be described with reference to FIGS. In the third embodiment, components that are the same as those described above will be given the same or corresponding reference numerals, and detailed descriptions thereof will be omitted, and the description will focus on the features of the present embodiment.

  As shown in FIGS. 3A and 3B, the gap between the single or plural low-pressure side outer peripheral seal lands 92CL and the cylinder block 5 in the rotational direction Y1 of the rotary shaft 4 is provided in the circumferential direction. A step 102 that decreases is provided. The depth 102d of the step is about 10 to several hundred μm. Other configurations are the same as those in the first embodiment, as shown in FIGS. 3-1 and 3-2.

  According to the third embodiment, the following operation occurs in addition to the first embodiment.

  Since the low pressure side outer peripheral seal land 92CL is set higher than the conventional one, when the high pressure side of the valve plate 9C and the cylinder block 5 are opened for some reason, the low pressure side outer peripheral seal land 92CL and the cylinder block 5 In the low pressure side outer peripheral seal land 92CL provided with the step 102, the pressure of the working fluid between the low pressure side outer peripheral seal land 92CL and the cylinder block 5 is obtained due to the damming effect in the step 102. Is further increased, and a large reaction force is generated in the direction of closing the high pressure side of the valve plate 9C, so that a large moment is generated and an effect of eliminating the opening on the high pressure side is obtained. In addition, by providing step 102, the generated pressure increases. Effective in preventing seizure.

  The step 102 can be provided not only on the low pressure side outer peripheral seal land 92CL but also on the low pressure side inner peripheral seal land.

  Next, a swash plate type hydraulic pump according to a fourth embodiment will be described with reference to FIGS. In the fourth embodiment, components that are the same as those described above are given the same or clear reference numerals, and detailed descriptions thereof are omitted, and the characteristic portions of the present embodiment will be mainly described.

  As illustrated in FIG. 4A and FIG. 4C, the single or plural high-pressure side outer peripheral seal lands 92DH are provided with tapered surfaces 103 that extend in the radial direction. The tapered surface 103 is formed so that its height decreases from the inner peripheral side to the outer peripheral side of the valve plate 9D. The taper depth 103d is about 10 to several hundred μm. In the fourth embodiment, as in the first to third embodiments, there is no difference in height in the high pressure side outer peripheral seal land 92DH and the low pressure side outer peripheral seal land 92DL.

  In the fourth embodiment, the high pressure side outer peripheral seal land 92DH is formed so that its height decreases toward the outer peripheral side, and therefore, for some reason, the high pressure side of the valve plate 9D and the cylinder block 5 are opened. In some cases, an increase in pressure at the high-pressure side outer peripheral seal land 92DH is suppressed, thereby eliminating the opening of the valve plate 9D on the high-pressure side. When the opening on the high pressure side of the valve plate 9D occurs, the working fluid that flows radially outward due to the centrifugal force by the rotation of the cylinder block 5 flows on the tapered surface 103 that spreads in the radial direction. An increase in pressure at the land 92DH is suppressed. Thus, also in 4th Embodiment, the ratio of the load (pressure) which the seal land of a high voltage | pressure side has is set small compared with the low voltage | pressure side.

  The tapered surface 103 can be provided not only on the high-pressure side outer peripheral seal land 92DH but also on the high-pressure side inner peripheral seal land 92DH.

  Next, a swash plate type hydraulic pump according to a fifth embodiment will be described with reference to FIGS. In the fifth embodiment, components that are the same as those described above are given the same or clear reference numerals, and detailed descriptions thereof are omitted, and the characteristic portions of the present embodiment will be mainly described.

  As illustrated in FIGS. 5A and 5C, the single or multiple high-pressure side outer peripheral seal lands 92EH are densely provided with a plurality of grooves 104 in the rotational direction Y1 of the rotary shaft 4. The depth of these grooves (steps) 104 is about several μm to several tens of μm. In the fifth embodiment, as shown in FIG. 5B, the high pressure side outer peripheral seal land 92EH and the low pressure side outer peripheral seal land 92EL have no difference in height as in the first to third embodiments. .

  Next, the operation of the fifth embodiment will be described.

  In a normal state (when the high pressure side of the valve plate 9E is not open), the plurality of grooves 104 of the high pressure side outer peripheral seal land 92EH are similar to the hydrodynamic bearing by the spiral groove, and the recesses 105 of the groove 104 and the cylinder block 5 Since a relatively large pressure (load) of the working fluid is generated in the narrow gap, the force for supporting the cylinder block 5 as a bearing is larger than that in the case of a flat surface instead of the groove 104. For this reason, image sticking is prevented. As shown in FIG. 6, when there is a step in the groove 104, the pressure generated when the gap between the valve plate and the cylinder block 5 is narrow in a normal state as compared with a flat and no step. Is expensive.

  On the other hand, when the high pressure side of the valve plate 9E is opened, the gap between the recess 105 of the groove 104 and the cylinder block 5 widens, so that the working fluid drains on the high pressure side and the clearance on the high pressure side becomes good. The pressure of the working fluid decreases. Thereby, as shown in FIG. 6, opening of the valve plate 9 </ b> E on the high-pressure side is suppressed as compared with the case where there is no groove 104.

  Further, since the working fluid generated by sliding between the cylinder block 5 and the valve plate 9E is cooled by the working fluid in the recesses 105 of the other grooves 104, seizure is prevented.

  The groove 104 can be provided not only in the high pressure side outer peripheral seal land 92EH but also in the high pressure side inner peripheral seal land.

  As described above, in the first to fifth embodiments, when the opening of the valve plate is generated on the high pressure side, the pressure on the high pressure side is decreased and the pressure on the low pressure side is increased. Suppress opening. Therefore, as described above, the balance of the load (pressure) of each of the high-pressure side seal land and the low-pressure side seal land is changed. By relatively increasing the load ratio of the low-pressure side seal land, when the gap between the high-pressure side seal land and the cylinder block 5 is opened, the generation of pressure on the high-pressure side seal land is suppressed. A large reaction force is generated in the seal land on the low pressure side.

It is a figure which shows the sealing surface of the valve plate of 1st Embodiment of the swash plate type fluid pressure apparatus of this invention. It is CC sectional drawing of FIGS. 1-1. It is a figure which shows the sealing surface of the valve plate of 2nd Embodiment of the swash plate type fluid pressure apparatus of this invention. It is DD sectional drawing of FIGS. It is EE sectional drawing of FIGS. It is a figure which shows the sealing surface of the valve plate of 3rd Embodiment of the swash plate type fluid pressure apparatus of this invention. It is FF sectional drawing of FIGS. It is GG sectional drawing of FIGS. It is a figure which shows the sealing surface of the valve plate of 4th Embodiment of the swash plate type fluid pressure apparatus of this invention. It is HH sectional drawing of FIGS. It is a figure which shows the sealing surface of the valve plate of 5th Embodiment of the swash plate type fluid pressure apparatus of this invention. It is II sectional drawing of FIGS. It is JJ sectional drawing of FIGS. It is a graph which shows the characteristic of the clearance gap and pressure of the valve plate of 5th Embodiment of the swash plate type fluid pressure apparatus of this invention. It is sectional drawing which shows the structure of the conventional swash plate type fluid pressure apparatus. It is the sectional view on the AA line of FIG. It is the BB sectional drawing of FIG.

Explanation of symbols

4 Rotating shaft 5 Cylinder block 6 Piston 7 Piston shoe 8 Swash plate 9A Valve plate 12 Suction port 13 Discharge port 15 Working fluid chamber 16A Low pressure port 17A High pressure port 90A Sliding surface 91A Inner peripheral seal land 92A Outer seal land 92AH High pressure side outer periphery Seal land 92AL Low pressure side outer peripheral seal land 93A Intermediate seal land D Height difference

Claims (5)

A cylinder block provided rotatably,
A piston provided in the cylinder block so as to be capable of reciprocating and having a piston shoe at one end;
A swash plate portion on which the piston shoe slides;
A low-pressure port that serves as a flow path for relatively low-pressure fluid and a high-pressure port that serves as a flow path for relatively high-pressure fluid, and slides on the cylinder block to bring fluid in the cylinder block into a sealing surface A swash plate type fluid pressure device equipped with a valve plate for sealing
The swash plate type fluid pressure device, wherein a height of the high pressure port side on the sealing surface of the valve plate is set lower than that of the low pressure port side. In the swash plate type fluid pressure device according to claim 1,
Furthermore,
The swash plate type fluid pressure is characterized in that the low pressure port side of the sealing surface of the valve plate is set to have a height on the downstream side in the rotational direction higher than a height on the upstream side in the rotational direction of the cylinder block. machine. A cylinder block provided rotatably,
A piston provided in the cylinder block so as to be capable of reciprocating and having a piston shoe at one end;
A swash plate portion on which the piston shoe slides;
A low-pressure port that serves as a flow path for relatively low-pressure fluid and a high-pressure port that serves as a flow path for relatively high-pressure fluid, and slides on the cylinder block to bring fluid in the cylinder block into a sealing surface A swash plate type fluid pressure device equipped with a valve plate for sealing
The swash plate type fluid pressure device characterized in that the high pressure port side of the sealing surface of the valve plate is set to have a height that decreases toward the radially outer side. A cylinder block provided rotatably,
A piston provided in the cylinder block so as to be capable of reciprocating and having a piston shoe at one end;
A swash plate portion on which the piston shoe slides;
A low-pressure port that serves as a flow path for relatively low-pressure fluid and a high-pressure port that serves as a flow path for relatively high-pressure fluid, and slides on the cylinder block to bring fluid in the cylinder block into a sealing surface A swash plate type fluid pressure device equipped with a valve plate for sealing
A swash plate type fluid pressure device characterized in that a plurality of recesses communicating in the radial direction are formed along the rotation direction of the cylinder block on the high pressure port side on the sealing surface of the valve plate. A cylinder block provided rotatably,
A piston provided in the cylinder block so as to be capable of reciprocating and having a piston shoe at one end;
A swash plate portion on which the piston shoe slides;
A low-pressure port that serves as a flow path for relatively low-pressure fluid and a high-pressure port that serves as a flow path for relatively high-pressure fluid, and slides on the cylinder block to bring fluid in the cylinder block into a sealing surface A swash plate type fluid pressure device equipped with a valve plate for sealing
The swash plate type fluid pressure device is characterized in that the load balance of the valve plate is configured such that the high pressure port side of the seal surface is smaller than the low pressure port side.

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