JP2018053865A - Fluid pressure pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluid pressure pump capable of preventing deterioration of pump efficiency even in a case where a temperature of fluid rises.SOLUTION: An intermediate member 30 is arranged in a pump chamber PS of a pump housing 20, and a pump rotor is arranged in a rotor storage chamber RS of the intermediate member 30. The intermediate member 30 has a peripheral partition wall part 31 along an inner peripheral wall 24 forming the pump chamber PS, and a main partition wall part 32 along a first inner wall 25 forming the pump chamber PS, and on an opposite side to the main partition wall part 32, an opening is formed. On a second inner wall 26 forming the pump chamber PS, provided is an energization member 36 configured to energize the opening of the intermediate member 30 to a direction of approaching the second inner wall.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fluid pressure pump in which a pump rotor is rotatably accommodated in a pump housing.

  As a fluid pressure pump, Patent Document 1 describes a technology in which a gear pump rotor including an outer rotor and an inner rotor is housed in a pump housing chamber of a pump housing, and the gear pump sets thermal expansion in a radial direction smaller than an axial direction. Has been.

  In Patent Document 1, a resin containing a fibrous filler is used for the outer rotor and the inner rotor, and the thermal expansion coefficient in the radial direction is made smaller than the axial direction due to the fiber orientation.

JP 2014-206072 A

  As described in Patent Document 1, in an internal gear type pump rotor in which an outer rotor and an inner rotor are formed using a resin containing fibers, a change in meshing amount due to a coefficient of thermal expansion is suppressed, and pump efficiency is increased. .

  However, it is difficult to ensure high accuracy in the case where the outer rotor and the inner rotor are formed using a resin material, compared to the case where the outer rotor and the inner rotor are formed using a metal material. Moreover, as described in Patent Document 1, it is considered difficult to orient the fibrous filler so that the thermal expansion in the radial direction is smaller than the axial direction.

  Considering the process of connecting the metal drive shaft to the inner rotor, the drive shaft cannot be driven and connected to the resin inner rotor, and when a resin inner rotor is used, a dedicated fitting structure is formed. Such a process is also required.

  From this, the effectiveness of forming the outer rotor and the inner rotor with a metal material will be recognized again.For example, in a vehicle such as an automobile, as a fluid pressure pump that sends out lubricating oil of an engine oil pan, it is made of aluminum. Considering the fluid pressure pump using the pump housing and the iron pump rotor, it is necessary to consider the influence of thermal expansion.

  In other words, when the temperature of the lubricating oil rises as the engine operates, the clearance at the boundary between the inner surface of the pump housing and the outer surface of the pump rotor increases due to the difference in coefficient of thermal expansion, which reduces the pump efficiency. It leads to.

  For these reasons, there is a need for a fluid pressure pump that does not decrease pump efficiency even when the temperature of the fluid rises.

A feature of the present invention is that a pump housing having a pump chamber surrounded by an inner peripheral wall having a circular cross-section centered on an axis, and a first inner wall and a second inner wall in a posture orthogonal to the axis;
A peripheral partition wall portion in a posture along the inner peripheral wall and a main partition wall portion in a posture along the first inner wall are accommodated in the pump chamber. An intermediate member in which an opening is formed;
A pump rotor rotatably accommodated in the rotor accommodating space of the intermediate member;
A biasing member that biases the opening of the intermediate member in a direction to approach the second inner wall;
The difference in coefficient of thermal expansion between the pump rotor and the intermediate member is less than a set value, and the difference in coefficient of thermal expansion between the intermediate member and the pump housing exceeds a set value.

  According to this characteristic configuration, the difference in the coefficient of thermal expansion between the intermediate member and the pump rotor is less than the set value. Therefore, when the outer diameter of the pump rotor is increased as the fluid temperature rises, the inner diameter of the peripheral partition wall is the same. However, the difference is small, and the expansion of the gap between the outer periphery of the pump rotor and the inner periphery of the peripheral partition wall can be suppressed. Further, the main partition wall portion of the intermediate member is disposed on the opposite side of the pump rotor from the second inner wall, and the state in which the main partition wall portion is brought close to the end surface of the pump rotor can be maintained by the biasing force of the biasing member acting. .

In other words, in this configuration, for example, the outer rotor and the inner rotor can be configured with high precision using an iron-based sintered material, and the pump housing is more thermally expanded than an iron-based material such as an aluminum material. Even when a material having a high rate is used, the leakage of fluid when the temperature of the fluid rises can be suppressed by using an iron-based material for the intermediate member.
Therefore, a fluid pressure pump is configured in which the pump efficiency does not decrease even when the temperature of the fluid rises. In particular, this configuration also realizes energy saving in order to suppress fluid leakage.

A feature of the present invention is that a pump housing having a pump chamber surrounded by an inner peripheral wall having a circular cross-section centered on an axis, and a first inner wall and a second inner wall in a posture orthogonal to the axis;
A peripheral partition wall portion in a posture along the inner peripheral wall and a main partition wall portion in a posture along the first inner wall are accommodated in the pump chamber. An intermediate member in which an opening is formed;
A pump rotor rotatably accommodated in the rotor accommodating space of the intermediate member;
A biasing member that biases the opening of the intermediate member in a direction to approach the second inner wall;
The difference in coefficient of thermal expansion between the pump rotor and the intermediate member exceeds a set value, and the difference in coefficient of thermal expansion between the intermediate member and the pump housing is less than a set value.

  According to this characteristic configuration, since the difference in the coefficient of thermal expansion between the intermediate member and the pump rotor exceeds the set value, for example, a material whose outer diameter of the pump rotor is larger than the inner diameter of the intermediate member is used as the temperature of the fluid increases. However, when the temperature of the fluid rises, the intermediate member can suppress the expansion of the outer diameter of the pump rotor. In addition, even when the outer diameter of the peripheral partition wall of the intermediate member increases as the fluid temperature rises, the inner diameter of the inner peripheral wall of the pump housing increases in the same way, so the difference is small and the expansion of these gaps is suppressed. it can. Further, the main partition wall portion of the intermediate member is disposed on the opposite side of the pump rotor from the second inner wall, and the state in which the main partition wall portion is brought close to the end surface of the pump rotor can be maintained by the biasing force of the biasing member acting. .

That is, in this configuration, for example, the pump rotor is configured by using an aluminum material for the outer rotor and the inner rotor, and an iron-based material is used for the pump housing and the intermediate member. Leakage can be suppressed.
Therefore, a fluid pressure pump is configured in which the pump efficiency does not decrease even when the temperature of the fluid rises. In particular, this configuration also realizes energy saving in order to suppress fluid leakage.

As another configuration, the pump rotor is configured as an internal gear type with an outer rotor that is rotatably accommodated in the rotor accommodating space, and an inner rotor that is accommodated inside the outer rotor,
When the discharge pressure acting on the fluid in the pump rotor exceeds a set value, the biasing force of the biasing member is allowed to allow the intermediate member to move away from the pump rotor by the action of the discharge pressure. A value may be set.

  According to this, when the discharge pressure exceeds the set value, the intermediate member is displaced in a direction away from the pump rotor against the urging force of the urging member, and the inner surface of the main partition wall portion of the intermediate member and the pump rotor A gap is formed between the two. By forming the gap in this manner, a part of the fluid on the discharge side can escape to the suction side, and an excessive increase in pressure can be suppressed. That is, it is possible to configure a fluid pressure pump that suppresses the action of excessive pressure without using a relief valve.

  As another configuration, a portion of the rotor accommodating space where the discharge pressure acts and a communication hole communicating with the outside of the intermediate member in the pump chamber may be formed in the main partition wall portion.

  According to this, since the discharge pressure of the pump rotor acts on the pump chamber via the communication hole, the pressure in the space between the main partition wall and the pump chamber is maintained at the discharge pressure, and the intermediate member is separated from the pump rotor. It is possible to suppress displacement in the direction in which it is performed. Thereby, the urging | biasing force of an urging member can be made to act appropriately, and the position of an intermediate member can be maintained.

It is a cross section of an oil pump. It is the II-II sectional view taken on the line of FIG. It is sectional drawing which shows the operating state of the intermediate member at the time of the raise of load. It is a disassembled perspective view which shows an intermediate member, an inner rotor, an outer rotor, etc. It is sectional drawing of the pump part of the oil pump of another embodiment (a). It is sectional drawing which shows the operation state of the intermediate member at the time of the raise of load with the oil pump of another embodiment (a).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Basic configuration]
As shown in FIG. 1, a motor housing 10 and a pump housing 20 are connected, the motor housing 10 includes the electric motor 1, and the pump housing 20 includes an intermediate member 30 and a pump unit 2. An oil pump 100 is configured.

  The oil pump 100 is provided in a hybrid vehicle or a vehicle in which idle stop is performed, and enables oil (an example of fluid) to be supplied to a transmission such as a CVT even in a situation where the engine is stopped.

  The motor housing 10 is made of a resin material, and the pump housing 20 is made of an aluminum material. The oil pump 100 is configured to drive the pump unit 2 by a drive shaft 11 driven by the electric motor 1. The motor housing 10 includes a control unit 15 at the end opposite to the pump housing 20. Yes.

[Electric motor / drive shaft]
As shown in FIGS. 1 and 2, the drive shaft 11 is disposed coaxially with the drive shaft core X and is rotatably supported by the pump housing 20. The motor rotor 12 is connected to one shaft end of the drive shaft 11, and the inner rotor 4 of the pump unit 2 is connected to the other end.

  The electric motor 1 includes a motor rotor 12 in which a plurality of permanent magnets 12M are embedded, and a stator 13 disposed in a region surrounding the motor rotor 12. The stator 13 is inserted into the motor housing 10 and is configured by winding a coil 13b around a stator core 13a.

  The electric motor 1 is configured as a brushless DC motor, but may be configured as a synchronous motor or a three-phase motor.

  The control unit 15 includes a cover body 15a attached to the end of the motor housing 10 and a substrate 15b accommodated inside the cover body 15a, and rotates the electric motor 1 in response to an external control signal. Control. That is, the electric power supplied to the coil 13b of the stator 13 is controlled.

[Pump housing / pump]
As shown in FIGS. 1 to 4, the pump housing 20 is configured by connecting a first housing 21 and a second housing 22, and a concave space formed in the first housing 21 is formed into a plate-shaped first. The pump chamber PS is formed by being closed by the two housings 22.

  The pump chamber PS is formed as a space surrounded by the inner peripheral wall 24, the first inner wall 25, and the second inner wall 26. The inner peripheral wall 24 is formed in a circular cross-sectional shape in the first housing 21 around a rotor axis Y that is parallel to the drive axis X. The first inner wall 25 is formed in the first housing 21 in a posture orthogonal to the rotor axis Y. The second inner wall 26 is formed in the second housing 22 in a posture orthogonal to the rotor axis Y.

  The intermediate member 30 is accommodated in the pump chamber PS, and the pump unit 2 is accommodated in the rotor accommodating space RS of the intermediate member 30. The configuration of the intermediate member 30 will be described later.

  The pump unit 2 includes an internal gear type pump rotor including an inner rotor 4 and an outer rotor 5 that are arranged coaxially with the drive shaft core X.

  The inner rotor 4 is formed of an iron-based sintered metal and includes a plurality of external teeth 4A. The outer rotor 5 includes a plurality of inner teeth 5 </ b> A that are formed of iron-based sintered metal like the inner rotor 4 and mesh with the outer teeth 4 </ b> A of the inner rotor 4. The outer periphery of the outer rotor 5 is formed in a cylindrical surface centered on the rotor axis Y.

  In the second housing 22, a suction region 28 that is low in the pump portion 2 is formed in a groove shape, and a suction port 28 </ b> P communicates therewith. A discharge region 29 having a high pressure in the pump unit 2 is formed in a groove shape, and a discharge port 29P communicates with the discharge region 29.

[Intermediate member]
As described above, the inner rotor 4 and the outer rotor 5 are formed of iron-based sintered metal, and the intermediate member 30 is set such that the difference between the thermal expansion coefficient and the thermal expansion coefficient of the intermediate member 30 is less than a set value. The iron material is used. Further, the thermal expansion coefficient of the aluminum material constituting the pump housing 20 is larger than the thermal expansion coefficient of the intermediate member 30.

  In this configuration, when the temperature of the oil rises because the difference in coefficient of thermal expansion between the intermediate member 30 and the pump housing 20 exceeds the set value, the outer diameter of the peripheral partition wall portion 31 of the intermediate member 30 increases, and the pump The inner diameter of the inner peripheral wall 24 of the housing 20 is enlarged, and the gap between them is enlarged. However, since the difference in coefficient of thermal expansion between the outer rotor 5 and the intermediate member 30 is less than the set value, the outer diameter of the outer rotor 5 and the outer diameter of the peripheral partition wall 31 of the intermediate member 30 even when the oil temperature rises. Can be substantially equal. Therefore, the gap between the outer surface of the outer rotor 5 and the inner surface of the peripheral partition wall portion 31 of the intermediate member 30 is hardly enlarged, and oil leakage is suppressed.

  In this description, the description of the difference between the thermal expansion coefficient and the thermal expansion coefficient between the sintered metal constituting the inner rotor 4 and the outer rotor 5 and the intermediate member 30 and the thermal expansion coefficient between the intermediate member 30 and the pump housing 20 are provided. The “set value” is used to explain the difference between the two, but the two types of “set value” may be the same value or different values.

  As shown in FIGS. 1 to 4, the intermediate member 30 is accommodated in the pump chamber PS and has a peripheral partition wall portion 31 in a posture along the inner peripheral wall 24 and a main partition wall portion 32 in a posture along the first inner wall 25. And opening is formed in the opposite side to the main partition part 32 by forming rotor accommodating space RS inside.

  That is, the intermediate member 30 is formed in a generally covered cylinder shape, and a shaft insertion hole 34 through which the drive shaft 11 is inserted coaxially with the drive shaft core X is formed in the main partition wall 32. The shaft insertion hole 34 is formed with an inner diameter sufficiently larger than the outer diameter of the drive shaft 11 so as not to transmit the rotational force of the drive shaft 11 to the intermediate member 30 when the electric motor 1 is driven.

  The rotor housing space RS of the intermediate member 30 has an inner diameter slightly larger than the outer diameter of the outer rotor 5 and slightly larger than the dimension of the outer rotor 5 in the direction along the rotor axis Y so that the outer rotor 5 can be rotatably accommodated. It is formed as a dimensional space.

  Thereby, the whole pump part 2 is accommodated in a state in which the opening edge of the peripheral partition wall part 31 of the intermediate member 30 is in contact with the surface of the second housing 22.

  The outer diameter of the peripheral partition wall 31 of the intermediate member 30 is set to a value slightly smaller than the inner diameter of the inner peripheral wall 24 of the pump chamber PS. The dimension in the direction along the rotor axis Y of the peripheral partition wall 31 is set smaller than the dimension in the direction along the rotor axis Y of the inner peripheral wall 24 of the pump chamber.

  Thus, a gap is formed between the outer surface of the main partition wall 32 of the intermediate member 30 and the first inner wall 25 of the pump chamber PS, and an elastic ring 36 as an urging member is interposed in this gap.

[Operation mode: operation and effect of the embodiment]
With such a configuration of the oil pump 100, the inner rotor 4 rotates integrally with the drive shaft 11 by driving the electric motor 1, and the outer rotor 5 rotates in conjunction with this. Along with this rotation, a negative pressure acts on the suction region 28, so that oil is sucked from the suction port 28P, and the sucked oil is sent from the discharge region 29 to the discharge port 29P.

  Further, when the temperature of the oil rises as the engine temperature rises, the inner rotor 4, the outer rotor 5, the intermediate member 30, and the pump housing 20 are thermally expanded. In this situation, the distance between the outer surface of the main partition wall 32 of the intermediate member 30 and the inner peripheral wall 24 of the pump chamber PS is increased. However, since the difference between the coefficient of thermal expansion between the inner rotor 4 and the outer rotor 5 and the coefficient of thermal expansion of the intermediate member 30 is less than a set value (because it is substantially equal), the inner wall of the rotor housing space RS and the outer wall of the outer rotor 5 The gap at the boundary of no expansion. As a result, oil leakage can be suppressed, pump efficiency can be maintained high, and energy saving can also be realized.

  Further, when the load acting on the discharge port 29P increases during the operation of the oil pump 100 and the discharge pressure exceeds the set value, the main partition wall portion 32 of the intermediate member 30 is increased as the pressure in the rotor housing space RS increases. A high pressure acts on the inner surface side. By the action of this pressure, the intermediate member 30 is separated from the second housing 22 against the urging force of the elastic ring 36 as shown in FIG. As a result, a communication space G is created between the inner rotor 4, the outer rotor 5, and the main partition wall 32 of the intermediate member 30, and the high-pressure side oil can be released to the low-pressure side via this communication space G. Eliminates the effect of pressure.

  That is, when the load acting on the discharge port 29P is within the assumed range, the end of the peripheral partition wall 31 of the intermediate member 30 is brought into contact with the second inner wall 26, and the load acting on the discharge port 29P is set to the set value. The biasing force of the elastic ring 36 is set so that the intermediate member 30 can be displaced away from the second inner wall 26 when exceeding the above. Thereby, even if it does not have a relief valve, the effect of excessive pressure is eliminated and the inconvenience of damaging the pump part 2 etc. is suppressed.

  As the oil temperature rises, the gap between the outer surface of the peripheral partition wall 31 of the intermediate member 30 and the boundary portion of the inner peripheral wall 24 of the pump chamber PS increases, but the oil does not flow into this gap, and the pump efficiency is increased. There is no reduction. Further, the intermediate member 30 is configured to be accommodated in the pump chamber PS so as to be rotatable about the rotor axis Y. However, since the rotor axis Y is eccentric with respect to the drive axis X, the oil pump Even in a situation where a rotational force acts on the intermediate member 30 when driving 100, the rotation of the intermediate member 30 is prevented by the drive shaft 11 coming into contact with the shaft insertion hole 34.

  In this way, the oil pump 100 simply fits the covered cylindrical intermediate member 30 into the pump chamber PS of the pump housing 20 and fits the pump rotor (the inner rotor 4 and the outer rotor 5) into the rotor housing space RS of the intermediate member 30. It becomes the composition.

  In this configuration, it is possible to use an aluminum material that is easy to process and lightweight as the pump housing 20, and has high wear resistance for the inner rotor 4 and the outer rotor 5, and is an iron-based sintered metal that can form teeth with high accuracy. Can be used. Moreover, as described above, even when the temperature of the oil rises, the pump efficiency is maintained high, and the inconvenience of damaging the pump portion 2 and the like can be suppressed without providing a relief valve.

[Another embodiment]
In addition to the above-described embodiments, the present invention may be configured as follows (the components having the same functions as those of the embodiments are given the same numbers and symbols as those of the embodiments).

(A) As shown in FIGS. 5 and 6, a pressure balancing communication hole 35 is formed in the main partition wall 32 of the intermediate member 30. The communication hole 35 is formed at a position where the fluid from the region (discharge region 29) where the discharge pressure is high in the pump unit 2 is supplied to the space between the first inner wall 25 and the main partition wall 32 in the pump chamber PS. Has been.

  In another embodiment (a), a pair of disc springs 37 are used as the urging members, and an annular portion in which the opening portion of the peripheral partition wall portion 31 of the intermediate member 30 is fitted into the second inner wall 26 of the second housing 22. A recess 27 is formed.

  With such a configuration, the pressure oil of the pump unit 2 is supplied to the intermediate gap between the first inner wall 25 and the main partition wall 32 in the pump chamber PS through the communication hole 35. For this reason, the pressures acting on the inner surface side and the outer surface side of the main partition wall 32 are balanced, and only the urging force of the disc spring 37 acts on the intermediate member 30. Thereby, the intermediate member 30 maintains the state in which the opening edge of the peripheral partition wall 31 abuts against the bottom wall portion of the annular recess 27.

  From this configuration, the gap at the boundary with the outer wall of the outer rotor 5 does not expand even when the temperature of the oil rises, similar to that described above in [Operation Mode]. Can be kept high. When the discharge pressure exceeds a set value as the load acting on the discharge port 29P increases, the intermediate member 30 resists the biasing force of the disc spring 37 as shown in FIG. The communication space G is created by displacement in the direction away from the valve, and the problem of damaging the pump unit 2 and the like is suppressed by eliminating the action of excessive pressure without a relief valve.

  Thus, when the intermediate member 30 is displaced against the urging force of the disc spring 37 due to the action of the load, the positional relationship in which the end portion on the opening side of the peripheral partition wall portion 31 of the intermediate member 30 does not come out of the annular recess 27. It can also be maintained. By maintaining such a positional relationship, it is possible to always bring the outer peripheral surface of the outer rotor 5 into contact with the inner surface of the peripheral partition wall 31 of the intermediate member 30 and to stabilize the relative positional relationship between them.

(B) Similar to the configuration shown in FIGS. 1 to 4, the motor housing 10, the pump housing 20, and the intermediate member 30 are provided, the outer surface of the main partition wall 32 of the intermediate member 30 and the first inner wall of the pump chamber PS. The oil pump 100 is configured to include an elastic ring 36 in the gap between the two.

  In the configuration of the other embodiment (b), the inner rotor 4 and the outer rotor 5 are formed of an aluminum material, and the pump housing 20 and the intermediate member 30 are formed of an iron-based material. Thereby, the difference between the thermal expansion coefficients of the outer rotor 5 and the intermediate member 30 constituting the pump rotor exceeds the set value, and the difference between the thermal expansion coefficients of the intermediate member 30 and the pump housing 20 is set to be less than the set value. Is done.

  With such a configuration, the outer diameter of the pump rotor (outer diameter of the outer rotor 5) tends to increase due to the thermal expansion coefficient as the oil temperature rises. However, the thermal expansion coefficient of the intermediate member 30 is greater than the thermal expansion coefficient of the pump rotor. Since it is small, the intermediate member 30 suppresses the expansion of the outer diameter of the pump rotor (the outer diameter of the outer rotor 5). Further, although the intermediate member 30 and the pump housing 20 are thermally expanded as the oil temperature rises, the difference in the coefficient of thermal expansion is less than the set value (because they are substantially equal), so the peripheral partition wall 31 of the intermediate member 30 Expansion of the outer diameter and the inner diameter of the inner peripheral wall 24 of the pump housing 20 and the gap can be suppressed, and oil leakage can be suppressed.

  Further, the main partition wall portion 32 of the intermediate member 30 is disposed on the opposite side of the pump rotor from the second inner wall, and the biasing force of the elastic ring 36 as the biasing member acts, whereby the main partition wall portion 32 is connected to the pump rotor ( It is possible to maintain a state in which the end faces of the inner rotor 4 and the outer rotor 5) are approached.

  Thus, in another embodiment (b), although the thermal expansion coefficient of the intermediate member 30 is set larger than the thermal expansion coefficient of the outer rotor 5, the thermal expansion coefficient of the intermediate member 30 is substantially equal to the thermal expansion coefficient of the pump housing 20. By making them equal, the oil leakage between the peripheral partition wall 31 of the intermediate member 30 and the inner peripheral wall 24 of the pump housing 20 is suppressed.

  As a modification of this another embodiment (b), the inner rotor 4 and the outer rotor 5 may be formed of iron-based sintered metal, and the pump housing 20 and the intermediate member 30 may be formed of aluminum material. good.

  In this alternative embodiment (b), the difference between the thermal expansion coefficient and the thermal expansion coefficient between the inner rotor 4, the outer rotor 5 and the intermediate member 30, and the difference between the thermal expansion coefficients between the intermediate member 30 and the pump housing 20 are also explained. Although “setting values” are used in the description, these two types of “setting values” may be the same value or different values.

(C) The drive source of the fluid pressure pump is not limited to the electric motor, and may be configured to be driven by the driving force from the crankshaft of the engine, for example.

  The present invention can be used for a fluid pressure pump in which a pump rotor is rotatably housed in a pump housing.

4 Inner rotor 5 Outer rotor 20 Pump housing 24 Inner peripheral wall 25 First inner wall 26 Second inner wall 30 Intermediate member 31 Peripheral partition wall portion 32 Main partition wall portion 35 Communication hole 36 Elastic ring (biasing member)
37 Belleville spring (biasing member)
PS Pump chamber RS Rotor housing space Y Rotor shaft

Claims (4)

A pump housing having a pump chamber surrounded by an inner peripheral wall having a circular cross section centered on the shaft core, and a first inner wall and a second inner wall in a posture orthogonal to the shaft core;
A peripheral partition wall portion in a posture along the inner peripheral wall and a main partition wall portion in a posture along the first inner wall are accommodated in the pump chamber. An intermediate member in which an opening is formed;
A pump rotor rotatably accommodated in the rotor accommodating space of the intermediate member;
A biasing member that biases the opening of the intermediate member in a direction to approach the second inner wall;
A fluid pressure pump in which a difference in coefficient of thermal expansion between the pump rotor and the intermediate member is less than a set value, and a difference in coefficient of thermal expansion between the intermediate member and the pump housing exceeds a set value. A pump housing having a pump chamber surrounded by an inner peripheral wall having a circular cross section centered on the shaft core, and a first inner wall and a second inner wall in a posture orthogonal to the shaft core;
A peripheral partition wall portion in a posture along the inner peripheral wall and a main partition wall portion in a posture along the first inner wall are accommodated in the pump chamber. An intermediate member in which an opening is formed;
A pump rotor rotatably accommodated in the rotor accommodating space of the intermediate member;
A biasing member that biases the opening of the intermediate member in a direction to approach the second inner wall;
A fluid pressure pump in which a difference in coefficient of thermal expansion between the pump rotor and the intermediate member exceeds a set value, and a difference in coefficient of thermal expansion between the intermediate member and the pump housing is less than a set value. The pump rotor is configured in an internal gear type with an outer rotor that is rotatably accommodated in the rotor accommodating space, and an inner rotor that is accommodated inside the outer rotor,
When the discharge pressure acting on the fluid in the pump rotor exceeds a set value, the biasing force of the biasing member is allowed to allow the intermediate member to move away from the pump rotor by the action of the discharge pressure. The fluid pressure pump according to claim 1 or 2, wherein a value is set.   The part which discharge pressure acts among the said rotor accommodating space, and the communicating hole connected to the exterior of the said intermediate member among the said pump chambers are formed in the said main partition part as described in any one of Claims 1-3. The fluid pressure pump described.

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