JP6794745B2 - Fluid pressure pump - Google Patents

Description

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

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

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

Japanese Unexamined Patent Publication No. 2014-206072

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

However, it is difficult to ensure high accuracy in the case where the outer rotor and the inner rotor are formed by using a resin material as compared with the case where the outer rotor and the inner rotor are formed by 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 that in the axial direction.

Considering the process of connecting the metal drive shaft to the inner rotor, it is not possible to drive the drive shaft into the resin inner rotor to connect it, and when using the resin inner rotor, a dedicated fitting structure is formed. Etc. are also required.

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

That is, when the temperature of the lubricating oil rises with the operation of the engine, 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 the coefficient of thermal expansion, which is inconvenient to reduce the pump efficiency. It leads to.

For this reason, a fluid pressure pump that does not reduce pump efficiency even when the temperature of the fluid rises is required.

A feature of the present invention is a pump housing having a pump chamber surrounded by an inner peripheral wall having a circular cross-sectional shape centered on the shaft core, and a first inner wall and a second inner wall in a posture orthogonal to the shaft core.
It is housed in the pump chamber and has a peripheral partition wall portion having a posture along the inner peripheral wall and a main partition wall portion having a posture along the first inner wall, and by having a rotor accommodating space inside, it is on the opposite side of the main partition wall portion. An intermediate member with an opening and
A pump rotor rotatably accommodated in the rotor accommodating space of the intermediate member,
It is provided with an urging member that urges the opening of the intermediate member in a direction of approaching the second inner wall, and also includes a urging member.
Wherein is the difference in the thermal expansion rate of the pump rotor and the intermediate member exceeds the set value, Ri the difference is set below value der coefficient of thermal expansion between said intermediate member and the pump housing,
The pump rotor is made of aluminum material.
The pump housing and the intermediate member is that that is formed by an iron-based material.

According to this characteristic configuration, the difference in the coefficient of thermal expansion between the intermediate member and the pump rotor exceeds the set value. Therefore, as the temperature of the fluid rises, for example, a material whose outer diameter of the pump rotor expands from the inner diameter of the intermediate member is used. However, when the temperature of the fluid rises, the intermediate member can suppress the expansion of the outer diameter of the pump rotor. Further, even if the outer diameter of the peripheral partition wall of the intermediate member increases as the temperature of the fluid rises, the inner diameter of the inner peripheral wall of the pump housing also increases, 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 arranged on the side of the pump rotor opposite to the second inner wall, and the urging force of the urging member acts to maintain the state in which the main partition wall portion is brought close to the end face of the pump rotor. ..

That is, in this configuration, to configure the pump rotor using an aluminum material and the outer rotor and the inner rotor, by using the material of the ferrous in the pump housing and the intermediate member, the leakage of fluid when the temperature of the fluid rises 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, in this configuration, energy saving is also realized in order to suppress fluid leakage.

As another configuration, the pump rotor is configured as an inscribed gear type by an outer rotor rotatably accommodated in the rotor accommodating space and an inner rotor accommodated inside the outer rotor.
When the discharge pressure acting on the fluid in the pump rotor exceeds a set value, the urging force of the urging member allows the intermediate member to be displaced in the direction 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 the direction away from the pump rotor against the urging force of the urging member, and the inner surface of the main partition wall of the intermediate member and the pump rotor are displaced. A gap is formed between the and. By forming the gap in this way, a part of the fluid on the discharge side can be released to the suction side to suppress an excessive increase in pressure. That is, a fluid pressure pump that suppresses the action of excessive pressure can be configured without using a relief valve.

As another configuration, a portion of the rotor accommodating space on which 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 is applied to the pump chamber through 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 the displacement in the direction of pumping. As a result, the urging force of the urging member can be appropriately applied to maintain the position of the intermediate member.

It is a cross section of an oil pump. FIG. 2 is a sectional view taken along line II-II of FIG. It is sectional drawing which shows the operating state of the intermediate member at the time of increasing a load. It is an exploded perspective view which shows the intermediate member, the inner rotor, the outer rotor and the like. It is sectional drawing of the pump part of the oil pump of another embodiment (a). It is sectional drawing which shows the operating state of the intermediate member at the time of the load increase in 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, the motor housing 10 and the pump housing 20 are connected, the motor housing 10 is provided with the electric motor 1, and the pump housing 20 is provided with the intermediate member 30 and the pump portion 2 as a fluid pressure pump. The 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 when 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 an electric motor 1, and has a control unit 15 at an end of the motor housing 10 opposite to the pump housing 20. There is.

[Electric motor / drive shaft]
As shown in FIGS. 1 and 2, the drive shaft 11 is arranged on a coaxial core with the drive shaft core X, and is rotatably supported by the pump housing 20. The motor rotor 12 is connected to one 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 arranged in a region surrounding the motor rotor 12. The stator 13 is inserted into the motor housing 10, and the coil 13b is wound around the 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 housed inside the cover body 15a, and rotates the electric motor 1 in response to a control signal from the outside. Control. That is, the power supplied to the coil 13b of the stator 13 is controlled.

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

The pump chamber PS is formed as a space surrounded by an inner peripheral wall 24, a first inner wall 25, and a second inner wall 26. The inner peripheral wall 24 has a circular cross-sectional shape formed in the first housing 21 centering on the rotor shaft core Y parallel to the drive shaft core 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 housed in the pump chamber PS, and the pump unit 2 is housed in the rotor housing space RS of the intermediate member 30. The configuration of the intermediate member 30 will be described later.

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

The inner rotor 4 is made of an iron-based sintered metal and has a plurality of external teeth 4A. Like the inner rotor 4, the outer rotor 5 is formed of an iron-based sintered metal and includes a plurality of internal teeth 5A that mesh with the outer teeth 4A of the inner rotor 4. The outer circumference of the outer rotor 5 is formed on a cylindrical surface centered on the rotor axis Y.

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

[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 so that the difference between the coefficient of thermal expansion of these and the coefficient of thermal expansion of the intermediate member 30 is less than the set value. Iron material is used for. Further, the coefficient of thermal expansion of the aluminum material constituting the pump housing 20 is larger than the coefficient of thermal expansion of the intermediate member 30.

In this configuration, since the difference in the coefficient of thermal expansion between the intermediate member 30 and the pump housing 20 exceeds the set value, when the temperature of the oil rises, the outer diameter of the peripheral partition wall portion 31 of the intermediate member 30 expands, and the pump The inner diameter of the inner peripheral wall 24 of the housing 20 is expanded, and these gaps are expanded. However, since the difference in the 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 portion 31 of the intermediate member 30 even when the oil temperature rises. Can be approximately 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 expanded, and oil leakage is suppressed.

In this description, the difference between the coefficient of thermal expansion and the coefficient of thermal expansion between the sintered metal constituting the inner rotor 4 and the outer rotor 5 and the intermediate member 30 and the coefficient of thermal expansion between the intermediate member 30 and the pump housing 20 will be described. Although the "set value" is used to explain the difference between the two types, 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 housed 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. By forming the rotor accommodation space RS inside, an opening is formed on the side opposite to the main partition wall portion 32.

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

The rotor accommodating 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 in the direction along the rotor axis Y of the outer rotor 5 so that the outer rotor 5 can be rotatably accommodated. It is formed as a space of dimensions.

As a result, the entire pump portion 2 is accommodated in a state where the opening edge of the peripheral partition wall portion 31 of the intermediate member 30 is in contact with the surface of the second housing 22.

Further, the outer diameter of the peripheral partition wall portion 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 of the peripheral partition wall portion 31 in the direction along the rotor shaft core Y is set to be smaller than the dimension of the inner peripheral wall 24 of the pump chamber in the direction along the rotor shaft core Y.

As a result, a gap is formed between the outer surface of the main partition wall portion 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.

[Operating mode: Action / effect of the embodiment]
From 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 out from the discharge region 29 to the discharge port 29P.

Further, when the temperature of the oil rises as the temperature of the engine rises, the inner rotor 4, the outer rotor 5, the intermediate member 30, and the pump housing 20 thermally expand. 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 the set value (because they are substantially equal), the inner wall of the rotor accommodating space RS and the outer wall of the outer rotor 5 The gap at the boundary of the is not enlarged. As a result, oil leakage can be suppressed, pump efficiency can be maintained high, and energy saving can be realized.

Further, when the load acting on the discharge port 29P increases and the discharge pressure exceeds the set value during the operation of the oil pump 100, the pressure of the rotor accommodating space RS increases and the main partition wall portion 32 of the intermediate member 30 increases. High pressure acts on the inner surface side of. Due to the action of this pressure, as shown in FIG. 3, the intermediate member 30 is separated from the second housing 22 against the urging force of the elastic ring 36.
As a result, a communication space G is created between the inner rotor 4 and the outer rotor 5 and the main partition wall portion 32 of the intermediate member 30, and the oil on the high pressure side can be released to the low pressure side through the communication space G, which is excessive. Eliminate the effects of pressure.

That is, when the load acting on the discharge port 29P is within the assumed range, the end portion of the peripheral partition wall portion 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 the set value. The urging force of the elastic ring 36 is set so as to allow the intermediate member 30 to be displaced away from the second inner wall 26 when the above value is exceeded. As a result, even if the relief valve is not provided, the action of excessive pressure is eliminated and the inconvenience of damaging the pump portion 2 and the like is suppressed.

As the temperature of the oil 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 expands, but the oil does not flow into this gap, and the pump efficiency is improved. It does not decrease. Further, the intermediate member 30 is rotatably housed in the pump chamber PS about the rotor shaft core Y, but since the rotor shaft core Y is eccentric with respect to the drive shaft core X, the oil pump Even in a situation where a rotational force acts on the intermediate member 30 when the 100 is driven, 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 tubular intermediate member 30 into the pump chamber PS of the pump housing 20, and fits the pump rotor (inner rotor 4 and outer rotor 5) into the rotor accommodating space RS of the intermediate member 30. The configuration is as follows.

In this configuration, it is possible to use a lightweight aluminum material that is easy to process as the pump housing 20, and the inner rotor 4 and the outer rotor 5 have high wear resistance, and an iron-based sintered metal capable of forming teeth with high accuracy. Can be used. Moreover, as described above, the pump efficiency can be maintained high even when the temperature of the oil rises, and the inconvenience of damaging the pump portion 2 or the like can be suppressed even if the relief valve is not provided.

[Another Embodiment]
The present invention may be configured as follows in addition to the above-described embodiment (those having the same functions as those in the embodiment are designated by the same number and reference numeral as those in the embodiment).

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

Further, in the other embodiment (a), a pair of disc springs 37 are used as the urging members, and 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. The recess 27 is formed.

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

From this configuration, as in the case described in the [Operating mode] above, even if the oil temperature rises, the gap at the boundary with the outer wall of the outer rotor 5 does not expand, so that oil leakage is suppressed and the pump efficiency is suppressed. Can be kept high. Then, when the discharge pressure exceeds the set value as the load acting on the discharge port 29P increases, the intermediate member 30 opposes the urging force of the disc spring 37 and the second inner wall 26, as shown in FIG. The communication space G is created by displacing in the direction away from the above, and the inconvenience of damaging the pump portion 2 and the like is suppressed by eliminating the action of excessive pressure even if the relief valve is not provided.

When the intermediate member 30 is displaced against the urging force of the disc spring 37 due to the action of the load in this way, the positional relationship is such that the end portion of the intermediate member 30 on the opening side of the peripheral partition wall portion 31 does not come out of the annular recess 27. It is also possible to maintain. By maintaining such a positional relationship, it is possible to keep the outer peripheral surface of the outer rotor 5 in constant contact with the inner surface of the peripheral partition wall portion 31 of the intermediate member 30 and to stabilize these relative positional relationships.

(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, and the outer surface of the main partition wall portion 32 of the intermediate member 30 and the first inner wall of the pump chamber PS. An elastic ring 36 is provided in the gap between the oil pump 100 and the oil pump 100.

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

From such a configuration, the outer diameter of the pump rotor (outer diameter of the outer rotor 5) tends to increase due to the coefficient of thermal expansion as the temperature of the oil rises, but the coefficient of thermal expansion of the intermediate member 30 is higher than the coefficient of thermal expansion 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 thermally expand as the temperature of the oil rises, the difference in the coefficient of thermal expansion between them is less than the set value (because they are substantially equal), so that the peripheral partition wall portion 31 of the intermediate member 30 The outer diameter of the pump housing 20 and the inner diameter of the inner peripheral wall 24 of the pump housing 20 and the expansion of the gap are suppressed, and oil leakage can be suppressed.

Further, the main partition wall portion 32 of the intermediate member 30 is arranged on the side opposite to the second inner wall of the pump rotor, and the urging force of the elastic ring 36 as the urging member acts to cause the main partition wall portion 32 to be pumped. The state of being close to the end faces of the inner rotor 4 and the outer rotor 5) can be maintained.

As described above, in the separate embodiment (b), the coefficient of thermal expansion of the intermediate member 30 is set to be larger than the coefficient of thermal expansion of the outer rotor 5, but the coefficient of thermal expansion of the intermediate member 30 is abbreviated as the coefficient of thermal expansion of the pump housing 20. By making them equal, it is possible to suppress oil leakage between the peripheral partition wall portion 31 of the intermediate member 30 and the inner peripheral wall 24 of the pump housing 20.

As a modification of the other embodiment (b), a configuration in which the inner rotor 4 and the outer rotor 5 are formed of an iron-based sintered metal and the pump housing 20 and the intermediate member 30 are formed of an aluminum material may be adopted. good.

In this other embodiment (b), the difference in the coefficient of thermal expansion and the coefficient of thermal expansion between the inner rotor 4, the outer rotor 5, and the intermediate member 30 and the difference in the coefficient of thermal expansion between the intermediate member 30 and the pump housing 20 are explained. Although the "set value" is used in the explanation, these two types of "set value" 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 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 bulkhead 32 Main bulkhead 35 Communication hole 36 Elastic ring (urging member)
37 Belleville spring (biasing member)
PS Pump room RS Rotor accommodation space Y Rotor shaft core

Claims (3)

A pump housing having a pump chamber surrounded by an inner peripheral wall having a circular cross-sectional shape centered on the shaft core, and a first inner wall and a second inner wall in a posture orthogonal to the shaft core.
It is housed in the pump chamber and has a peripheral partition wall portion having a posture along the inner peripheral wall and a main partition wall portion having a posture along the first inner wall, and by having a rotor accommodating space inside, it is on the opposite side of the main partition wall portion. An intermediate member with an opening and
A pump rotor rotatably accommodated in the rotor accommodating space of the intermediate member,
It is provided with an urging member that urges the opening of the intermediate member in a direction of approaching the second inner wall, and also includes a urging member.
Wherein is the difference in the thermal expansion rate of the pump rotor and the intermediate member exceeds the set value, Ri the difference is set below value der coefficient of thermal expansion between said intermediate member and the pump housing,
The pump rotor is made of aluminum material.
The pump housing and the intermediate member, the fluid pressure pump that is formed by an iron-based material. The pump rotor is configured as an inscribed gear type by an outer rotor rotatably accommodated in the rotor accommodating space and an inner rotor accommodated inside the outer rotor.
When the discharge pressure acting on the fluid in the pump rotor exceeds a set value, the urging force of the urging member allows the intermediate member to be displaced in the direction away from the pump rotor by the action of the discharge pressure. The fluid pressure pump according to claim 1, wherein a value is set. The fluid pressure pump according to claim 1 or 2 , wherein a portion of the rotor accommodating space on which the discharge pressure acts and a communication hole communicating with the outside of the intermediate member in the pump chamber are formed in the main partition wall portion. ..

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