JP2009203836A - Internal gear pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve improvement of fuel consumption, and to solve problems such as cavitation by providing an internal gear pump as a variable displacement type. <P>SOLUTION: In the gear 3, pumping action is carried out by displacement change of a pump chamber between internal teeth of an outer gear 31 and external teeth of an inner gear 32 by engine-driving the inner gear 32 and co-rotating the outer gear 31. Delivery oil from the pump 3 is subjected to gear change control and lockup control of a converter, apply pressure Pap is low during low engine rotation, and it becomes high during high engine rotation. A seal member 33 receiving the apply pressure Pap largely displaces the inner gear 32 in an axis direction as an engine speed becomes high as indicated in (a)-(c), and a pump displacement is lowered due to lowering of an override amount L. Even under low engine speed with a small pump delivery amount, a necessary amount of hydraulic fluid can be delivered, and even under high engine speed wherein the pump delivery amount becomes slightly excessive, a hydraulic fluid delivery amount can be maintained at a predetermined amount. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a gear pump useful for an oil pump of an automatic transmission, and more particularly to an internal gear pump in which an inner gear is arranged eccentrically in the outer gear so as to mesh with the inner teeth of the outer gear. It is about change technology.

In this type of pump, although the pump discharge amount increases as the rotational speed increases, the pump capacity that is a characteristic of the pump is almost fixed.
When using such a pump with a fixed pump capacity, for example, a case of using it as an oil pump of an automatic transmission,
It is necessary to determine the pump specifications so that the pump capacity is such that the required amount of oil can be discharged even at a low engine speed where the pump discharge amount decreases because the engine is driven.

For this reason, the pump capacity becomes excessive under operating conditions where the engine speed is high, and drainage is performed without using an excess of the pump discharge flow rate.
The extra driving load is applied to the pump by that amount, and the fuel efficiency of the engine that drives the pump deteriorates.
Excessive pump flow rate causes cavitation and causes abnormal noise, and erosion causes deterioration of pump durability.

Note that some rotary vane pumps have a variable pump capacity by varying the amount of eccentricity of the rotor relative to the vane inscribed surface. It is difficult to maintain the meshing state between the outer gear and the inner gear, and the amount of eccentricity between them cannot be made variable.
In addition, even if the pump capacity variable technology of the rotary vane pump is applied to the internal gear pump, this pump capacity variable technology can be used with a special dedicated structure such as a variable eccentricity structure or a dedicated control device (hydraulic control system). Hydraulic circuit and solenoid valve) are indispensable, and these not only increase the weight and cost, but also deteriorate the mountability of the pump.

Conventionally, as described in Patent Document 1, as a technology for varying the pump capacity of the internal gear pump, the pump capacity can be varied by controlling the side clearance between the axial side surfaces of the outer gear and the inner gear and the pump housing. The technology to make is proposed.
JP-A-11-343882

  However, the pump capacity variable technology of the internal gear pump that controls the side clearance between the axial side surfaces of the outer gear and the inner gear and the pump housing eliminates the excess flow rate through the side clearance. However, the energy for discharging the excessive flow rate is saved, but the energy for sucking the excessive flow rate is not saved, and energy loss (deterioration of fuel consumption) is unavoidable.

  In addition, since the excessive flow rate is sucked, when this excess amount is eliminated through the side clearance, cavitation occurs and causes abnormal noise, or erosion occurs and deteriorates the durability of the pump. Concerns cannot be completely wiped out.

  In view of the above circumstances, the present invention provides an internal gear pump in which the pump capacity is variable without sucking an excessive flow rate, based on a technical idea different from the pump capacity varying technique described in Patent Document 1. Thus, an object of the present invention is to solve all the above-mentioned problems and concerns as well as problems caused by the pump displacement varying technique described in Patent Document 1.

For this purpose, the internal gear pump according to the invention is constructed as described in claim 1.
First, to explain the prerequisite internal gear pump,
The inner gear is arranged eccentrically in the outer gear so as to mesh with the inner teeth of the outer gear.

The present invention provides an internal gear pump of this type,
The inner gear and outer gear can be relatively displaced in the axial direction.
It is characterized in that the pump displacement can be changed by the relative displacement in the axial direction of the inner gear and the outer gear.

According to the internal gear pump according to the present invention described above, the inner gear and the outer gear can be relatively displaced in the axial direction, and the pump capacity is changed by the axial relative displacement of the inner gear and the outer gear.
Both the pump suction amount and pump discharge amount are determined by the relative axial position of the inner gear and outer gear (the axial length of the region where these gears overlap in the radial direction), and the internal gear pump exceeds this amount. There is no inhalation or discharge.

  Therefore, even when the pump capacity is reduced, only a corresponding amount of suction / discharge is performed, so that an excessive flow rate is not sucked and energy loss (deterioration of fuel consumption) is avoided. be able to.

  Moreover, since the excess flow rate is not inhaled, this excess amount is not excluded, and there is no concern about the occurrence of cavitation (abnormal noise) or erosion (deterioration of durability) due to this. Can be wiped off.

Furthermore, since it is an internal gear pump, since it is a variable pump capacity as described above, all the above-mentioned problems can be solved.
For example, when used as an oil pump for an automatic transmission,
Even if the pump specifications are determined so that the pump capacity can discharge the required amount of oil even at low engine speeds where the pump discharge volume is low,
Under the operating conditions where the engine speed is high, the pump discharge flow rate can be made appropriate by the decrease in the pump capacity.

Therefore, the pump discharge flow rate is not excessive, and the occurrence of cavitation (abnormal noise) and the occurrence of erosion (deterioration of the durability of the pump) due to the excessive amount can be avoided.
In addition, since the pump discharge flow rate does not become excessive, it is possible to prevent an excessive driving load from being applied to the pump and to prevent the fuel consumption of the engine from being deteriorated.

Furthermore, in order to make the pump capacity variable by the axial relative displacement of the inner gear and the outer gear,
The objective can be achieved without relying on the pump displacement variable technology of the rotary vane pump (pump displacement variable technology by eccentricity control), and a special dedicated structure such as a variable eccentricity structure or a dedicated control device (hydraulic control) Therefore, the internal gear pump can be of a variable pump capacity type without increasing the weight, increasing the cost, or deteriorating the mountability of the pump.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
FIG. 1 shows a main part of an automatic transmission having an internal gear pump according to an embodiment of the present invention, wherein 1 is a transmission case, 2 is a converter housing, and 3 is an oil pump.

  An internal gear pump according to an embodiment of the present invention is used as the oil pump 3 and is configured by incorporating a pump element described later in a space between the pump housing 4 and the pump cover 5.

The pump housing 4 and the pump cover 5 are connected to each other by a bolt 6, and an interconnected body of the pump housing 4 and the pump cover 5 closes the front end opening of the transmission case 1 facing the converter housing 2, and the bolt 7 The combined body of the pump housing 4 and the pump cover 5 is attached to the front end opening of the converter housing 2.
After this attachment, the converter housing 2 is fitted to the outer periphery of the pump housing 4 and brought into contact with the front end surface of the transmission case 1. In this state, the converter housing 2 is attached to the front end surface of the transmission case 1 with the bolts 8. To wear.

The hollow fixed shaft 9 is fitted into the center hole of the pump cover 5 to integrate them, and the hollow fixed shaft 9 extends from the pump cover 5 so as to protrude into the converter housing 2.
The input shaft 10 of the transmission gear mechanism housed in the transmission case 1 passes through the hollow fixed shaft 9 so as to be rotatable, and the tip of the transmission input shaft 10 projects into the converter housing 2.

The torque converter 11 is housed in the converter housing 2, and the torque converter 11 is disposed on the hollow fixed shaft 9 as described below, and is disposed on the tip of the transmission input shaft 10.
Here, the torque converter 11 mainly includes a pump impeller 12 as an input element, a turbine runner 13 as an output element, and a stator 14 as a reaction force element.

The pump impeller 12 is rotatably supported on the hollow fixed shaft 9 via a hollow pump drive shaft 15 attached to the center of the left end in the figure, and is attached to the converter cover so as to close the right end opening in the figure. 16 is connected to an engine crankshaft (not shown) through 16.
The turbine runner 13 is rotationally engaged with the tip of the transmission input shaft 10, and the stator 14 is placed on the hollow fixed shaft 9 via the one-way clutch 17 so as not to rotate in the reverse direction to the engine.

  Thus, the torque converter 11 causes the internal working fluid to collide with the turbine runner 13 by centrifugal force by the pump impeller 12 driven by the engine, and then returns the working fluid to the pump impeller 12 under the guidance of the stator 14 while the reaction force by the stator 14 is applied. The engine rotation can be transmitted from the pump impeller 12 to the turbine runner 13 and the transmission input shaft 10 while increasing the torque below. (Converter state)

The torque converter 11 has a built-in lock-up clutch piston 18 that can directly connect the pump impeller 12 that is the input element and the turbine runner 13 that is the output element in order to increase the transmission efficiency in the situation where the above torque increase is unnecessary. To do.
The lockup clutch piston 18 is rotationally coupled to the turbine runner 13 via a torsional damper 19, but is displaceable in the axial direction.
The lock-up clutch piston 18 is disposed so as to face the converter cover 16 and partitions the torque converter 11 into a lock-up chamber 20 and the converter chamber 21 between the lock-up clutch piston 18 and the converter cover 16.

A lockup chamber passage 22 communicating with the lockup chamber 20 and a converter chamber passage 23 communicating with the converter chamber 21 are set.
When the torque converter hydraulic fluid flows out from the converter chamber passage 23 sequentially from the lockup chamber passage 22 through the lockup chamber 20 and the converter chamber 21, the lockup clutch piston 18 moves away from the converter cover 16 and the pump impeller 12 and the turbine runner. The torque converter 11 is operated in the converter state without directly connecting 13.
On the other hand, when the torque converter hydraulic fluid flows out from the converter chamber passage 23 through the converter chamber 21 and the lockup chamber 20 through the lockup chamber passage 22 in sequence, the lockup clutch piston 18 is pressed by the converter cover 16 and the pump impeller 12 Further, the turbine runner 13 is directly connected, and the torque converter 11 is operated in a lock-up state.

The torque converter hydraulic oil is the same as that of the automatic transmission and uses the oil discharged from the oil pump 3. In this embodiment, the oil pump 3 is a variable displacement internal gear pump as follows. To do.
In other words, the oil pump 3 has an outer gear 31 and an inner gear 32 as main components as in the case of a normal internal gear pump, and the outer teeth 32a of the inner gear 32 are part of the inner teeth 31a of the outer gear 31 as shown in FIG. The center Oi of the inner gear 32 is decentered from the center Oo of the outer gear 31 so as to mesh with each other, and a pump chamber is defined between the inner teeth 31a of the outer gear 31 and the outer teeth 32a of the inner gear 32.

As shown in FIG. 1, the outer gear 31 is rotatably housed in the pump housing 4 as usual and positioned in the axial direction by the pump cover 5, but the inner gear 32 maintains the meshed state with the outer gear 31 and moves in the axial direction. Displaceable.
In order to keep the pump chamber defined between the inner teeth 31a of the outer gear 31 and the outer teeth 32a of the inner gear 32 during the displacement of the inner gear 32, the axial line is brought into contact with the end face of the inner gear 32 far from the torque converter 11. One end face seal member 33 in the direction and the other end face seal member 34 in the axial direction are provided in contact with the end face of the outer gear 31 close to the torque converter 11.

As shown in FIG. 2 (b) with hatching for the sake of convenience, the outer circumferential surface meshes with the inner teeth 31a of the outer gear 31 and can be displaced in the axial direction together with the inner gear 32. It is assumed that the corresponding end face of the pump chamber is continuously closed between the inner teeth 31a of the outer gear 31 and the outer teeth 32a of the inner gear 32.
As shown in FIG. 1, the axial end seal member 33 is axially slidably fitted into the pump cover 5 to define a pump capacity control hydraulic chamber 35, and the pump cover 5 A pump displacement control oil passage 36 is formed in

Via this oil passage 36, the hydraulic chamber 35 is supplied with an apply pressure (engagement pressure of the lockup clutch piston 18) Pap in the converter chamber 21, and by this apply pressure (engagement pressure of the lockup clutch piston 18) Pap. One end face seal member 33 (inner gear 32) in the axial direction is urged to the right in FIG.
A spring 37 as an elastic means is applied to the opposite end face of the inner gear 32 so as to oppose this urging force.
Therefore, the inner gear 31 is displaced to the axial position where the force due to the apply pressure (fastening pressure of the lockup clutch piston 18) Pap and the spring reaction force due to the spring 37 are balanced.

As shown in FIG. 2 (c) with hatching for convenience, the inner circumferential end meshes with the outer teeth 32a of the inner gear 32 and comes into close contact with the corresponding end surface of the outer gear 31. It is assumed that the corresponding end surface of the pump chamber between the inner teeth 31a of the outer gear 31 and the outer teeth 32a of the inner gear 32 is kept closed by close contact.
Therefore, the other end face seal member 34 in the axial direction is fitted in the pump housing 4 so as to be rotatable but not displaceable in the axial direction as shown in FIG.

  As shown in FIG. 1, the hollow pump drive shaft 15 is inserted into the pump housing 4, and the tip of the hollow pump drive shaft 15 enters the key groove 32b of the inner gear 32 (see also FIG. 2), and the pump drive shaft 15 rotates to the inner gear 32. Thus, the above-described oil pump 3 is driven by the engine.

Hereinafter, the operation of the oil pump 3 will be described.
In the oil pump 3, the inner gear 32 is driven by the engine, and the outer gear 31 is rotated around the inner gear 32, whereby a predetermined pump is generated by a change in volume of the pump chamber between the inner teeth 31a of the outer gear 31 and the outer teeth 32a of the inner gear 32 The operation is performed, and a predetermined amount of hydraulic oil corresponding to the rotation speed is discharged.
The oil discharged from the oil pump 3 is used for transmission operation including the shift control of the automatic transmission and the lock-up control of the torque converter 11.

  Therefore, the apply pressure Pap in the converter chamber 21 changes according to the engine speed, and when the engine speed is low, the torque converter 11 is brought into the converter state, so the apply pressure Pap is low and the engine speed is high. Accordingly, the apply pressure Pap increases because the torque converter 11 is brought into the lock-up state.

Therefore, the axial one-side seal member 33 that receives the applied pressure Pap and displaces the inner gear 32 in the axial direction displaces the inner gear 32 almost in the axial direction as shown in FIG. 3 (a) when the engine speed is low. It can not be done or it can be displaced slightly in the axial direction.
In this case, the override amount L of the inner gear 32 relative to the outer gear 31 (the axial length of the region where these gears overlap in the radial direction) is large, and the volume of each pump chamber is large, so that the pump capacity is large.
Therefore, a required amount of hydraulic fluid can be discharged even at a low engine speed with a small pump discharge amount.

As shown in FIGS. 3 (b) and 3 (c), the axial one side seal member 33 largely displaces the inner gear 32 against the spring 37 in the axial direction as shown in FIGS.
In this case, the override amount L of the inner gear 32 with respect to the outer gear 31 is reduced, and the volume of each pump chamber is reduced accordingly, so that the pump capacity is reduced.
Therefore, the hydraulic oil discharge amount can be kept at a predetermined amount even under a high engine speed at which the pump discharge amount becomes an excessive atmosphere, and it is possible to prevent this from becoming excessive.

By the way, according to the oil pump (internal gear pump) 3 of this embodiment,
The inner gear 32 can be displaced in the axial direction relative to the outer gear 31, and the pump displacement is changed by the relative axial displacement of the inner gear 32.
Both the pump suction amount and the pump discharge amount are determined by the axial relative positions of the inner gear 32 and the outer gear 31 (override amount L), and the oil pump (internal gear pump) 3 can perform suction and discharge exceeding this amount. Absent.

  Therefore, even at low engine speeds where the pump capacity is small, only a corresponding amount of intake / discharge is performed, and an excessive flow rate is not inhaled, resulting in a corresponding energy loss (deterioration of fuel consumption). It can be avoided.

  Moreover, since the excess flow rate is not inhaled, this excess amount is not excluded, and there is no concern about the occurrence of cavitation (abnormal noise) or erosion (deterioration of durability) due to this. Can be wiped off.

Furthermore, since it is an internal gear pump, it has the variable pump capacity as described above, so that the following effects can be obtained.
In the case of using as an oil pump of an automatic transmission as shown in the example,
Even if the pump specifications are determined so that the pump capacity can discharge the required amount of oil even at low engine speeds where the pump discharge volume is low,
Under the operating conditions where the engine speed is high, the pump discharge flow rate can be made appropriate by the decrease in the pump capacity.

Therefore, the pump discharge flow rate is not excessive, and the occurrence of cavitation (abnormal noise) and the occurrence of erosion (deterioration of the durability of the pump) due to the excessive amount can be avoided.
In addition, since the pump discharge flow rate does not become excessive, it is possible to prevent an excessive driving load from being applied to the pump and to prevent the fuel consumption of the engine from being deteriorated.

Furthermore, in order to make the pump capacity variable by the axial relative displacement of the inner gear 32 with respect to the outer gear 31,
The objective can be achieved without relying on the pump displacement variable technology of the rotary vane pump (pump displacement variable technology by eccentricity control), and a special dedicated structure such as a variable eccentricity structure or a dedicated control device (hydraulic control) Therefore, the internal gear pump can be of a variable pump capacity type without increasing the weight, increasing the cost, or deteriorating the mountability of the pump.

In the present embodiment, the axial gear one end face seal member 33 meshed with the inner teeth 31a of the outer gear 31 and brought into contact with the one axial end face of the inner gear 32, and the outer gear 32a of the inner gear 32 meshed with the outer gear 32a. The pump chamber is located between the inner teeth 31a of the outer gear 31 and the outer teeth 32a of the inner gear 32 even when the inner gear 32 is displaced in the axial direction with the axially other end face seal member 34 brought into contact with the other end face in the axial direction of 31. Was kept being defined,
Even though the inner gear 32 can be displaced in the axial direction in order to be of variable capacity, it does not hinder the pumping action described above.

Further, since the pump capacity control force that acts on the one axial side seal member 33 and the inner gear 32 is caused by the apply pressure Pap in the converter chamber 21 of the torque converter 11,
The capacity control of the oil pump 3 performed as described above appropriately matches the pump capacity required for the oil pump 3, so that it can be used during idling stop or idling operation with the transmission in a neutral state. It is possible to make the oil balance not excessive or deficient during all operations.
Therefore, it is ensured that the oil amount will be insufficient when the engine is running slowly, cavitation (abnormal noise) will occur due to excessive pump discharge flow when the engine is running at high speed, and erosion (deterioration of pump durability) will occur. Can be avoided.

Furthermore, since an elastic means such as a spring 37 acts on the inner gear 32 so as to face the apply pressure Pap,
By replacing the spring (elastic means) 37, the pump capacity characteristic with respect to the applied pressure Pap can be arbitrarily adjusted, and the effect of greatly increasing the degree of freedom in design can be achieved.

  In the above embodiment, the outer gear 31 is fixed in the axial direction and the inner gear 32 is displaced in the axial direction. Conversely, the inner gear 32 is fixed in the axial direction and the outer gear 31 is displaced in the axial direction. Of course, the idea of the present invention can be applied in the same way to achieve the same effect.

It is a vertical side view which shows the principal part of the automatic transmission which provided the internal gear pump which becomes one Example of this invention as an oil pump. FIG. 2 is a front view showing the inside of the oil pump in FIG. 1, wherein (a) is a front view showing the axial direction one side seal member and the other axial direction side seal member removed, and (b) is an axial direction one side. The front view shown in the state which attached the seal member, (c) is a front view shown in the state where it reversed right and left and the other axial direction seal member was attached. FIG. 2 is an explanatory diagram illustrating the principle of displacement control of the oil pump in FIG. 1. (a) is a diagram illustrating the principle of pump displacement control when the engine speed is low. FIG. FIG. 4C is a principle explanatory diagram showing a pump capacity control state when the engine speed is high, and FIG. 4C is a principle explanatory diagram showing a pump capacity control state when the engine speed is high.

Explanation of symbols

1 Transmission case
2 Converter housing
3 Oil pump (internal gear pump)
4 Pump housing
5 Pump cover
9 Hollow fixed shaft
10 Transmission input shaft
12 Pump impeller (torque converter input element)
13 Turbine runner (torque converter output element)
14 Stator
15 Pump drive shaft
16 Converter cover
17 One-way clutch
18 Lock-up clutch piston
19 Torsional damper
20 Lock-up room
21 Converter room
22 Lock-up room passage
23 Converter room passage
31 Outer Gear
31a Internal teeth
32 Inner gear
32a external teeth
32b keyway
33 Axial seal member
34 Seal on the other side in the axial direction
35 Pump capacity control hydraulic chamber
36 Pump capacity control oil passage
37 Spring (elastic means)

Claims (5)

In the internal gear pump in which the inner gear is arranged eccentrically in the outer gear so as to mesh with the inner teeth of the outer gear,
The inner gear and the outer gear can be relatively displaced in the axial direction,
An internal gear pump characterized in that the pump capacity can be changed by the axial relative displacement of the inner gear and the outer gear. In the internal gear pump according to claim 1,
An axial one-side end face seal member meshed with the inner teeth of the outer gear and brought into contact with the one axial end face of the inner gear;
An axial direction other side end face seal member meshed with the outer teeth of the inner gear and brought into contact with the axial direction other side end face of the outer gear;
An internal gear pump characterized in that, by these seal members, a pump chamber is continuously defined between the inner teeth of the outer gear and the outer teeth of the inner gear even during the axial relative displacement of the inner gear and the outer gear. The internal gear pump according to claim 2, wherein the outer gear is fixed in the axial direction, and the inner gear is displaced in the axial direction with respect to the outer gear to cause relative displacement in the axial direction of the inner gear and the outer gear.
A pump displacement control force in the corresponding axial direction is applied to the inner gear via the one axial end face seal member, and a predetermined axial reaction force in a direction opposite to the pump displacement control force is applied to the inner gear.
An internal gear pump characterized in that an inner gear is displaced relative to an outer gear at an axial position where the pump displacement control force and a predetermined axial reaction force are balanced. The internal gear pump according to claim 3, which is used for an automatic transmission having a torque converter that can be in a lockup state in which a torque converter input / output element is directly connected to a transmission system as appropriate.
An internal gear pump characterized in that a force generated by a torque converter apply pressure that puts the torque converter in a locked-up state on the one axial side seal member and an inner gear is used as the pump displacement control force. . In the internal gear pump according to claim 3 or 4,
An internal gear pump characterized in that the predetermined axial reaction force is generated by an elastic means.

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