JP2010144515A - Swash plate hydraulic rotary machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control a flow from a restriction part according to a change in the temperature of a pressure oil when the supply amount of the pressure oil to the sliding surface between a shoe and a swash plate is regulated by providing the restriction part in an oil guide path which is formed in the shoe. <P>SOLUTION: The pressure oil in a cylinder bore 10 is guided, through the oil guide path 21, to a static pressure pocket 22 at the slidable contact part of the shoe 12, to which a piston 11 sliding in the cylinder bore 10 of a cylinder block 3, which is in slidable contact with the tilted flat surface 4a of the swash plate 4. A land part 23 is formed around the static pressure pocket 22, and a storage part 26 having a restriction wall is formed in the body part 16 of the shoe 12. A flow passage restriction member 25 in which a restriction flow passage 24 is drilled is attached to the inside of the storage part 26. The flow passage restriction part 25 is formed of a member with a large coefficient of thermal expansion. The cross sectional area of the restriction flow passage 24 is changed according to the temperature of the pressure oil which flows therein. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a swash plate type hydraulic rotating machine used as a hydraulic pump or a hydraulic motor.

  A swash plate type hydraulic rotating machine constituting a hydraulic pump or a hydraulic motor is provided with a cylinder block having a plurality of cylinder bores formed in a casing, and is connected to the cylinder block in a state in which a rotating shaft is integrally rotated. Each has a piston slidably mounted. Further, a swash plate is provided on the cylinder block so as to face each other, and a shoe that is in sliding contact with the swash plate is connected to the piston so as to swing freely.

  Here, the swash plate has an inclined plane inclined with respect to the cylinder block and the rotation axis. When the cylinder block rotates, the shoe slides with respect to the swash plate. When the cylinder block rotates once, the piston connected to the shoe reciprocates in the cylinder bore by an amount corresponding to the inclination angle of the swash plate. It will be. As a result, when configured as a hydraulic pump, when the piston is extended from the cylinder bore by rotating the rotary shaft, the hydraulic oil is sucked in as the cylinder bore expands, and the piston enters the cylinder bore during operation. The hydraulic oil in the cylinder bore is pressurized and discharged. In addition, when the hydraulic rotating machine is configured as a hydraulic motor, the piston is extended by introducing pressure oil into the cylinder bore, and during this time, the shoe moves along the inclination of the swash plate. The cylinder block and the rotating shaft that rotates integrally with the cylinder block are driven to rotate. In the cylinder block, the surface opposite to the side facing the swash plate is in sliding contact with the valve plate, and a pair of ports communicating with the cylinder bore is formed on the valve plate, and the cylinder bore is between the ports. A top dead center and a bottom dead center that do not communicate with the port are formed.

  In the swash plate type hydraulic rotating machine having the above-described configuration, when the cylinder bore communicates with one of the pair of ports formed in the valve plate, the direction in which the piston is pushed from the cylinder bore, that is, the shoe is There is a possibility that seizing due to contact between metals occurs between the shoe and the swash plate due to the force that presses against the swash plate. In order to prevent this, the pressure oil in the cylinder bore is guided to the sliding contact surface between the shoe and the swash plate, the pressing force of the shoe against the swash plate is eased, and an appropriate lubricating film is held between them. As a result, friction loss can be reduced, the occurrence of seizure can be prevented, and the sliding operation of the shoe to the swash plate can be performed smoothly. For this purpose, an oil guide passage is formed in the piston and the shoe, and the oil guide passage is configured such that one end opens in the cylinder bore and the other end opens in the sliding contact surface between the shoe and the swash plate. ing.

Here, in order to smoothly slide the shoe against the swash plate and to prevent excessive pressing force from acting during that time, a static pressure pocket is formed on the sliding surface of the shoe against the swash plate. For example, as described in Japanese Patent Application Laid-Open No. H10-293707, the conventional one is known. In this static pressure pocket, pressure oil from the cylinder bore is introduced, and hydraulic pressure is applied in a direction opposite to the pressing force to the swash plate of the shoe. As a result, the pressing force when the shoe slides along the swash plate is relaxed, and the operation of the hydraulic rotating machine is performed smoothly. An annular land is formed on the outer surface of the static pressure pocket on the sliding contact surface of the shoe with the swash plate to minimize the flow of pressure oil from the static pressure pocket. It is made to function as a seal part.
JP 2006-17075 A

  As described above, by forming a static pressure pocket between the shoe and the swash plate and guiding the pressure oil in the cylinder bore, the pressing force of the shoe against the swash plate is relieved, and the lubricating film is formed on the sliding surface. Is formed. And since a pressure difference arises inside and outside a static pressure pocket, pressure oil will leak from between a land part and the surface of a swash plate from a static pressure pocket. This leakage becomes a pressure loss in the hydraulic rotary machine, and when configured as a hydraulic pump, the pump efficiency is reduced, and when configured as a hydraulic motor, it results in a loss of torque. Therefore, the pressing force acting between the shoe and the swash plate is suppressed by setting the area ratio between the land portion and the static pressure pocket on the sliding contact surface between the shoe and the swash plate to an appropriate value. An appropriate oil film is held on the surface, and the slidability therebetween is good, and the pressure loss due to the leakage of the pressure oil from the static pressure pocket is suppressed.

  By the way, since the hydraulic oil leaks from the static pressure pocket, it is necessary to flow an amount of hydraulic oil commensurate with the amount of leakage into the static pressure pocket and set the pressure in the static pressure pocket appropriately. And it is beneficial for suppressing pressure oil leakage. For this purpose, it is necessary to control the flow rate to the static pressure pocket by forming a throttle at the opening to the static pressure pocket in the oil guide passage.

  However, since the swash plate type hydraulic rotating machine is usually mounted on a construction machine, and the construction machine works outdoors, the hydraulic oil tank is affected by the outside air temperature. For this reason, the temperature of the hydraulic oil supplied to the hydraulic rotating machine varies greatly depending on the region and season. When the temperature of the hydraulic oil is low, the viscosity of the hydraulic oil increases. When the temperature of the hydraulic oil is high, the viscosity decreases. As described above, when the oil guide passage to the static pressure pocket is provided with a throttle and the oil guide flow rate to the static pressure pocket is set to a predetermined value, when the hydraulic oil temperature is low, the static pressure pocket is As a result, there is a risk that the oil film will be cut, and when the hydraulic oil temperature is high, the amount of pressure oil leakage increases.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a throttle portion in an oil guide passage formed in a shoe so as to provide a sliding surface between the shoe and the swash plate. In adjusting the supply amount of the pressure oil, the flow rate from the throttle portion can be adjusted according to the temperature change of the pressure oil.

  In order to achieve the above-described object, the present invention provides a cylinder block and a rotating shaft that rotates integrally with the cylinder block in a casing, and allows pistons to slide in a plurality of cylinder bores formed in the cylinder block. The piston is a swash plate type hydraulic rotating machine in which a shoe slidably contacting a swash plate opposed to the cylinder block so as to be adjustable in angle is connected to the piston, wherein the swash plate slides between the shoe and the swash plate. In order to lubricate the contact surface, an oil guide passage is formed in the piston and the shoe, and a throttle channel that communicates with the oil guide passage and opens in the sliding contact surface is formed in the shoe. A flow restrictor is provided, and the flow restrictor is composed of a member having a coefficient of thermal expansion greater than that of the main body of the shoe, and the cross sectional area of the flow varies according to the temperature of the pressure oil flowing through the restrictive flow. Make It is an its characterized in that a formed.

  The shoe structure is provided with an oil guide passage for guiding the pressure oil in the cylinder bore. However, a static pressure pocket is not provided on the sliding surface of the swash plate, and no special static pressure pocket is provided. Some have just opened the oil guide passage. Although the present invention can be applied to any one of them, it is desirable to have a configuration having a static pressure pocket in view of opening the throttle channel. That is, a circular static pressure pocket is formed on the sliding surface of the shoe against the swash plate, a sealing land is formed on the outer peripheral side of the static pressure pocket, and the throttle channel is opened to the static pressure pocket. The configuration. Here, since it is the land portion that is in sliding contact with the swash plate of the shoe, the entire shoe can be constructed as a single piece, and the portion of the land portion smoothly slides on the swash plate. For this reason, there is a configuration in which a base portion made of a material different from the main body portion of the shoe and made of a member having excellent slidability is provided.

  The shoe or the main body portion is composed of a highly rigid member such as carbon steel, and the material has a predetermined coefficient of thermal expansion. Therefore, the flow path restricting portion is made of a member having a larger coefficient of thermal expansion than that of the shoe main body, such as zinc or aluminum. A throttle channel is formed in the channel throttle unit, and when the temperature of the channel throttle unit is increased, the channel section of the throttle channel changes as a result of thermal deformation. The channel restricting portion is formed in a cylindrical shape that extends at least the entire length of the restricting channel. Then, a housing portion is formed in the main body portion of the shoe, and the flow passage restricting portion is mounted in the housing portion, and the outer peripheral surface of the flow passage restricting portion is inserted in a tightly fitted state in the housing portion. The housing portion functions as a restriction wall for the outer peripheral surface of the flow path restricting portion. As a result, when the temperature of the pressure oil flowing through the throttle channel rises and the channel throttle portion is thermally deformed, the channel cross-sectional area of the throttle channel is deformed in the direction of reduction, and the temperature change The followability of the change in the cross-sectional area of the flow path with respect to the is further improved.

  As described above, the flow passage restricting portion is provided by being inserted into the housing portion formed in the main body portion of the shoe. However, the flow passage restricting member is formed independently of the main body portion of the shoe, and this flow restricting member. Can be configured to be inserted into and fixed to the accommodating portion. This fixing can be performed by appropriate means such as press-fitting or screwing. Further, when the land portion is formed as a base portion made of a member having excellent slidability, the flow path restricting portion can be formed integrally with the base portion. Also in this case, a concave housing portion is formed in the main body portion of the shoe, and the flow passage restricting portion is inserted into the housing portion. Here, when mounting the base portion to the main body portion of the shoe, it is common to use casting. When the flow passage restricting portion is integrated with the base portion, the flow passage is simultaneously introduced when casting the base portion. The throttle part can also be fixed.

  The amount of hydraulic oil supplied to the sliding surface between the shoe and the swash plate is reduced by providing a throttle in the oil guide path and making this throttle variable a variable throttle whose flow path cross-sectional area changes with temperature changes. In adjusting, the flow rate from the throttle can be adjusted according to the temperature of the pressure oil, the flow rate can be increased when the viscosity of the pressure oil is high, and the flow rate is decreased when the viscosity of the pressure oil is low. Thus, an appropriate oil film can be held between the shoe and the swash plate, and leakage of pressurized oil from the sliding surface can be minimized.

    Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, FIG. 1 shows an overall configuration of a swash plate type hydraulic rotating machine. In the figure, reference numeral 1 denotes a casing of a hydraulic rotating machine, and the casing 1 is composed of a front casing 1a and a rear casing 1b. A valve plate 2, a cylinder block 3 and a swash plate 4 are mounted inside the casing 1, and a rotating shaft 5 is inserted into the casing 1 from the rear casing 1b side.

  The rotating shaft 5 is rotatably supported on the rear casing 1b via a bearing 6, and is connected to the cylinder block 3 so as to rotate integrally by spline coupling or the like through the swash plate 4 in a loosely fitted state. ing. Further, the rotary shaft 5 passes through the valve plate 2 in a loosely fitted state, and is rotatably supported by the front casing 1a via a bearing 7. The rotary shaft 5 serves as a drive shaft when configured as a hydraulic pump, and serves as an output shaft when configured as a hydraulic motor. Therefore, in the following description, the hydraulic rotating machine of the present invention is configured as a hydraulic pump, but it goes without saying that it can also be configured as a hydraulic motor.

  The cylinder block 3 is provided with a plurality of cylinder bores 10 in the circumferential direction. Here, it is desirable to provide an odd number of cylinder bores 10 such as 5 or 7. A piston 11 is slidably inserted in each cylinder bore 10, and a shoe 12 is connected to each piston 11. The shoe 12 is in contact with the swash plate 4, and when the rotary shaft 5 is driven to rotate, the cylinder block 3 rotates integrally. For this purpose, the rotating shaft 5 and the cylinder block 3 are connected via a spline or key. When the cylinder block 3 rotates, the shoe 12 slides along the inclined plane 4 a of the swash plate 4. Although not shown, a tilting mechanism is connected to the swash plate 4, and the tilting angle of the swash plate 4 can be changed by this tilting mechanism, so that a stroke corresponding to the tilting angle can be obtained. Thus, the piston 11 reciprocates in the cylinder bore 10.

  The valve plate 4 is formed with a pair of ports 13a and 13b. One port 13a is a suction port and the other port 13b is a discharge port. Both the ports 13a and 13b have an eyebrow shape, and each cylinder bore 10 is provided with a communication hole 14. The communication hole 14 is switched and connected to the ports 13a and 13b. Therefore, when the cylinder block 3 rotates, the piston 11 extends from the cylinder bore 10 while the communication hole 14 of the cylinder bore 10 is in communication with the port 13a, whereby the hydraulic oil is sucked into the cylinder bore 10 ( Suction process). Further, while the communication hole 14 is connected to the port 13b, the piston 11 enters the cylinder bore 10, and the hydraulic oil sucked during this time is pressurized and discharged from the port 13b (discharge stroke). ). Further, the transition from the port 13a to the port 13b and the transition from the port 13b to the port 13a become a bottom dead center and a top dead center at which the cylinder bore 10 does not communicate with both ports.

  The shoe 12 is connected to the piston 11 through a spherical joint so as to be swingable. The shoe 12 is held by the shoe pressing member 15 so as to be in sliding contact with the inclined plane 4 a of the swash plate 4. Yes. Therefore, the shoe 12 is not separated from the inclined plane 4a of the swash plate 4 not only during the discharge stroke but also during the suction stroke. The pressure oil in the cylinder bore 10 is guided to the sliding contact portion between the shoe 12 and the inclined plane 4 a of the swash plate 4. For this purpose, an oil guide passage 20 penetrating in the length direction is formed in the piston 11, and an oil guide passage 21 is also formed in the shoe 12. Are always in communication.

  FIG. 2 shows the configuration of the sliding contact portion between the shoe 12 and the inclined plane 4a of the swash plate 4, and FIG. 3 shows a bottom view of the shoe 12. As shown in FIG. As is clear from these drawings, a circular recess is provided at the end of the shoe 12, and this recess forms a static pressure pocket 22, and the outer periphery of the static pressure pocket 22 has a circular shape. An annular land portion 23 is formed. The pressure oil in the cylinder bore 10 is guided into the static pressure pocket 22 from the oil guide passages 20, 21, and the land portion 23 minimizes the flow of pressure oil from the static pressure pocket 22. The seal part for this is comprised. Therefore, only the land portion 23 of the shoe 12 is in sliding contact with the inclined plane 4a of the swash plate 4, and the inside of the static pressure pocket 22 is kept in a non-contact state with respect to the inclined plane 4a.

  The shoe 12 includes a main body portion 16 and a base portion 17. The main body portion 16 includes a spherical portion 16a that is swingably connected to the piston 11, and a pedestal portion 16b that is provided integrally with the spherical portion 16a. Has been. The pedestal 16b comes into sliding contact with the inclined plane 4a of the swash plate 4. However, the pedestal portion 16b does not directly contact the inclined plane 4a, but the base portion 17 is fixedly provided on the pedestal portion 16b. Here, since the shoe 12 is desired to have high rigidity, the shoe 12 is made of carbon steel or the like, and is not necessarily a member having good slidability. Therefore, a base part 17 made of a material having good slidability, for example, a material such as zinc, is attached to the bottom surface of the pedestal part 16b so as to be integrated by casting means or the like. Therefore, from the viewpoint of material, the shoe 12 is composed of a main body portion composed of a spherical portion 16a and a pedestal portion 16b and a base portion 17 made of a material different from the main body portion.

  The above-described static pressure pocket 22 is formed in the base portion 17, and the pressure oil in the cylinder bore 10 is guided into the static pressure pocket 22, but oil guide paths 20 and 21 are formed in the piston 11 and the shoe 12. The pressure oil flows into the static pressure pocket 22 through the oil guide paths 20 and 21. However, the flow path of the oil guide paths 20 and 21 does not communicate with the static pressure pocket 22 as it is, but the communicating portion to the static pressure pocket 22 is a throttle flow path 24. In addition, the throttle channel 24 is formed in the channel throttle member 25, and the throttle channel 24 is fixedly provided in the accommodating portion 26 provided in the shoe 12. Here, the accommodating part 26 is formed in the base part 16b which comprises the main-body part of the shoe 12, and the flow-path throttle member 25 with which this accommodating part 26 is mounted | worn is a member with a large thermal expansion coefficient, for example, zinc or It is comprised from metal materials, such as aluminum.

  The throttle channel 24 is a channel having a length extending over the entire length of the channel throttle member 25, and the channel throttle member 25 is screwed into the accommodating portion 26. Therefore, the inner wall of the accommodating portion 26 is in contact with the outer peripheral surface of the flow path restricting member 25, and the inner wall of the accommodating portion 26 functions as a regulating wall that restricts thermal expansion toward the outer peripheral side of the flow restricting member 25. Is.

  When the rotary shaft 5 is driven to rotate, the cylinder block 3 rotates integrally with the rotary shaft 5. A swash plate 4 is provided inside the casing 1, and a piston 11 is mounted in each cylinder bore 10 constituting the cylinder block 3, and a shoe that is in sliding contact with the inclined plane 4 a of the swash plate 4 is attached to the piston 11. 12 are connected. Therefore, when the cylinder block 3 rotates, the piston 11 reciprocates in the cylinder bore 10 by the shoe 12 that slides along the inclined plane 4a. While the cylinder bore 10 is connected to the port 13 a on the suction side of the valve plate 2, the piston 11 extends from the cylinder bore 10, and hydraulic oil is sucked into the cylinder bore 10 during this time. When the cylinder bore 10 is connected to the discharge-side port 13b, the piston 11 enters the cylinder bore 10, and the hydraulic oil in the cylinder bore 10 is pressurized and discharged from the port 13b. When the tilt angle of the swash plate 4 is changed by driving a tilt mechanism (not shown) connected to the swash plate 4, the discharge pressure and the discharge flow rate change.

  When the rotary shaft 5 is rotationally driven, the pressure in the cylinder bore 10 increases in the stroke in which the piston 11 enters the cylinder bore 10. This pressure acts on the end face of the piston 11 and presses the shoe 12 connected to the piston 11 against the inclined plane 4 a of the swash plate 4. However, the pressure in the cylinder bore 10 is guided to the static pressure pocket 22 formed between the shoe 12 and the inclined plane 4a, and a hydraulic reaction force that opposes the pressing force of the shoe 12 against the swash plate 4 acts. It will be.

  A land portion 23 is formed around the static pressure pocket 22, and the land portion 23 and the inclined plane 4a are sealed. However, since the inside of the casing 1 is in a low pressure state, a high pressure acts. An oil film is formed between the land portion 23 and the inclined plane 4a of the swash plate 4 from the static pressure pocket 22, and the pressure oil leaks from the gap. The flow rate from the cylinder bore 10 to the static pressure pocket 22 is limited by the throttle channel 24, and an amount of pressurized oil corresponding to the amount of leakage described above is supplied into the static pressure pocket 22. As a result, an appropriate oil film is formed between the shoe 12 and the inclined flat surface 4a to reduce friction loss, and the shoe 12 slides smoothly to prevent the occurrence of seizure or the like. In addition, since the amount of pressure oil supplied by the throttle channel 24 is limited, leakage of the pressure oil from that interval is minimized, and the volumetric efficiency can be maintained at a high level.

  By the way, the flow rate of the pressure oil flowing through the throttle channel 24 varies depending on its viscosity. That is, when the hydraulic oil is in a low temperature state, its viscosity increases and the flow rate of the throttle channel 24 decreases. On the other hand, when the temperature of the hydraulic oil rises, the viscosity decreases, and as a result, the flow rate of the throttle channel 24 increases. From the above, the flow rate of the throttle channel 24 is changed according to the temperature of the hydraulic oil flowing through the throttle channel 24. For this reason, the flow path restricting member 25 is formed of a member having a larger coefficient of thermal expansion than the main body portion 16 of the shoe 12.

  Accordingly, when the temperature of the pressure oil flowing into the static pressure pocket 22 rises, the flow path restricting member 25 is thermally expanded. The body portion of the shoe 12 has a coefficient of thermal expansion smaller than that of the flow restrictor 1 material 25, and the outer peripheral side of the flow restrictor 25 does not expand outward because the inner wall of the accommodating portion 26 serves as a regulating wall. To be regulated. For this reason, it expands toward the inner peripheral side. As a result, the channel cross-sectional area of the throttle channel 24 is reduced. On the other hand, when the ambient temperature decreases, the viscosity of the pressure oil flowing through the throttle channel 22 increases and the flow rate decreases. However, when the oil temperature is low, the flow restrictor 25 does not thermally expand, so that the restrictive flow 24 can ensure a large flow cross-sectional area.

  From the above, the throttle channel 24 exhibits the function of the variable throttle, and when the oil temperature rises, the flow rate of the pressure oil supplied to the static pressure pocket 22 decreases, and the amount of leakage from the land portion 23 Decrease. Further, when the oil temperature is low, the flow restrictor 25 does not thermally expand, so that the restrictive flow 24 can ensure a large flow cross-sectional area. As a result, the necessary pressure oil is supplied to the static pressure pocket 22 via the throttle channel 24, and an appropriate oil film is secured between the land portion 23 and the inclined plane 4 a of the swash plate 4.

  As described above, the flow rate of the pressure oil flowing through the throttle channel 24 changes according to the oil temperature, and the change in the throttle amount of the throttle channel 24 with respect to the change in the oil temperature is caused by the channel breakage of the throttle channel 24. This is based on the difference in the area and the total length of the flow path, and the coefficient of thermal expansion between the main body portion 16 of the shoe 12 and the flow path restricting member 25. Therefore, by setting these elements as appropriate, even if the oil temperature changes and the viscosity changes, an appropriate oil film can be held between the shoe 12 and the swash plate 4, and the cylinder block 3 The slidability of the shoe 12 during the rotation is maintained well. Further, even when the viscosity of the pressure oil in the cylinder bore 10 is lowered, the pressure oil leakage from between the inclined plane 4a of the swash plate 4 and the land portion 23 can be suppressed to the minimum, and the volumetric efficiency in the hydraulic pump Can be kept good.

  In the above-described embodiment, the flow path restricting member 25 is configured as an independent member, and is configured to be fixed to the accommodating portion 26 formed in the main body portion 16 of the shoe 12. However, as shown in FIGS. Further, in the shoe 112 composed of the main body 116 and the base portion 117, an annular projecting portion is integrally formed at the center position of the base portion 117, and this projecting portion serves as a flow passage restricting portion 125. Alternatively, the throttle channel 124 may be formed.

  In this second embodiment, the base portion 117, in particular the land portion 123 for defining the static pressure pocket 122, is made of zinc or the like in order to improve the slidability with respect to the inclined plane 4a of the swash plate 4. Although a member having high slidability is used, the base portion 117 is a member having a larger thermal expansion coefficient than the main body portion 116 of the shoe 112 made of carbon steel or the like. The body portion 116 of the shoe 112 is composed of a spherical portion 116a and a pedestal portion 116b, and the oil guide passage 121 drilled from the end portion of the spherical portion 116a is expanded at the portion of the pedestal portion 116b. The enlarged diameter portion functions as the accommodating portion 126. Therefore, the flow path restricting portion 125 constituting the base portion 117 is inserted into the accommodating portion 126. And the inner wall surface of the accommodating part 126 exhibits the function as a control wall which controls the outer peripheral surface of the flow-path restricting part 125. FIG.

  Also with the above configuration, when the pressure oil in the cylinder bore is introduced into the static pressure pocket 122 as in the first embodiment described above, the throttle flow is changed according to the temperature of the pressure oil. The flow passage cross-sectional area of the passage 124 can be changed, so that an appropriate oil film is held between the shoe 112 and the swash plate 4, and pressure oil leakage from the sliding surface therebetween is minimized. . Moreover, since the flow path restricting portion 125 is formed integrally with the base portion 117, when the base portion 117 is configured to be connected to the main body portion 116 by casting means, the flow restricting portion is integrally formed therewith. The 125 shoe 112 is assembled. Of course, the flow passage restricting portion 125 is assembled to the accommodating portion 126 by casting, and thus the outer peripheral surface of the flow restricting portion 125 is regulated. Accordingly, the amount of restriction by the restriction passage 124 is adjusted according to the temperature of the pressure oil flowing through the oil guide passage 121 based on the difference in coefficient of thermal expansion between the main body 116 and the base portion 117 of the shoe 112.

  By the way, in 1st Embodiment, since the flow-path throttle member 25 is comprised with the member independent of the main-body part 16 and the base part 17 of the shoe 12, it is what a special external force does not act on. It can be composed of a member having a desired coefficient of thermal expansion. Therefore, the throttle channel 24 can be made to have a short length by using a member whose expansion coefficient changes greatly when the oil temperature changes. On the other hand, in the second embodiment, the flow path restricting portion 125 is formed of a member integrated with the base portion 117, so that the change in the expansion rate with respect to the change in the oil temperature cannot be extremely increased. In this case, by increasing the length of the throttle channel 124, the flow rate change of the throttle channel 124 when the oil temperature change can be increased.

It is sectional drawing which shows the structure of the swash plate type hydraulic rotating machine of this invention. FIG. 2 is a cross-sectional view of a shoe used in the swash plate type hydraulic rotating machine of FIG. 1, showing the first embodiment of the present invention. FIG. 3 is a bottom view of FIG. 2. It is sectional drawing of the shoe which shows the 2nd Embodiment of this invention. FIG. 3 is a bottom view of FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Casing 2 Valve plate 3 Cylinder block 4 Swash plate 4a Inclination plane 5 Rotating shaft 10 Cylinder bore 11 Piston 12, 112 Shoe 15 Shoe holding member 16, 116 Main body part 16a, 116a Spherical part 16b, 116b Base part 17,117 Base part 20 , 21, 121 Oil guide path 22, 122 Static pressure pocket 23, 123 Land part 24, 124 Restriction flow path 125 Flow restriction part 26, 126 Storage part 125 a Flow restriction part

Claims (4)

A cylinder block and a rotating shaft that rotates integrally with the cylinder block are provided in the casing, and pistons are slidably mounted in a plurality of cylinder bores formed in the cylinder block, and the piston is attached to the cylinder block. In a swash plate type hydraulic rotating machine that connects a shoe that is in sliding contact with a swash plate that is oppositely arranged so that the angle can be adjusted,
In order to lubricate the sliding contact surface between the shoe and the swash plate, an oil guide passage is provided in the piston and the shoe,
The shoe is provided with a flow restrictor that communicates with the oil guide passage and forms a restrictive passage that opens in the sliding contact surface.
The flow passage restricting portion is formed of a member having a thermal expansion coefficient larger than that of the main body portion of the shoe, and the flow passage cross-sectional area is changed according to the temperature of the pressure oil flowing through the restrictive flow passage. A swash plate type hydraulic rotating machine. The slidable contact surface of the shoe with the swash plate is formed with a land portion on the outer peripheral side, and a static pressure pocket is formed inside the land portion, and the throttle channel opens into the static pressure pocket. The swash plate type hydraulic rotating machine according to claim 1, wherein the swash plate type hydraulic rotating machine is configured. The shoe is formed with a circular concave regulating wall that communicates with the oil guide passage, the flow restrictor is formed of a cylindrical member, and the outer peripheral surface of the flow restrictor is outwardly formed by the restricting wall. 3. The swash plate type hydraulic rotating machine according to claim 1, wherein the swash plate type hydraulic rotating machine is configured to be fixed to a mounting portion formed on the shoe in a state of being restricted so as not to bulge. The shoe is composed of a main body portion connected to the piston and a base portion formed by a member different from the main body portion, and the land portion and the static pressure pocket are formed in the base portion. The part is integrally formed with a flow restrictor as a cylindrical projecting part having a restrictive flow path leading to the oil guide passage, and the main body has an outer peripheral surface of the flow restrictor. 3. The swash plate type hydraulic rotating machine according to claim 2, wherein a regulating wall having a circular cross section is formed so as to be in close contact and not bulge outward.

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