ROTATING PUMP

The present application claims the benefit of priority of Japanese Patent Application No. 2014-22442 filed on Feb. 7, 2014, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1.Technical Field of the Invention

This disclosure relates generally to a rotating pump designed to suck and then discharge fluid, and more particularly to such a rotating pump which is useful for a brake system working to suck and discharge brake fluid to regulate the pressure thereof for controlling the braking force.

2. Background Art

Japanese Patent First Publication No. 2002-295376 teaches use of an internal gear pump, such as a trochoid pump, as a rotating pump for an automotive brake system. This type of rotating pump is made up of an inner rotor, an outer rotor, and a casing. The inner rotor is equipped with outer teeth formed on an outer periphery thereof. The outer rotor is equipped with inner teeth formed on an inner periphery thereof. The outer and inner rotors are mounted in the casing. Specifically, within the casing, the teeth of the inner rotor mesh with those of the outer rotor to define a plurality of cavities (i.e., clearances). If a line passing through the centers of the inner rotor and the outer rotor is defined as the center line of the pump, the pump has an inlet port (i.e., a suction side) and an outlet port (i.e., a discharge side) which are diametrically opposed to each other across the center line of the pump.

In operation of the pump, the inner rotor is rotated by a drive shaft, so that the outer rotor is rotated in the same direction as the inner rotor through the meshing of the outer teeth and the inner teeth. This causes the volumes of the cavities to increase and then decrease continuously to suck fluid from the inlet port and then discharge it from the outlet port every 360° rotation of the outer and inner rotors.

During the operation of the pump, gaps between the outer periphery of the outer rotor and the casing are broken down into a low-pressure region and a high-pressure region. A sealing member is, therefore, disposed on the outer periphery of the outer rotor to hermetically isolate the low-pressure and high-pressure regions from each other. Specifically, the casing has two cavities formed on portions of the inner circumference thereof which face the outer circumference of the outer rotor. Sealing mechanisms each made up of a resin member and a rubber member are disposed in the cavities, respectively. The rubber member is placed on the bottom of the cavity of the casing, while the resin member is laid between the rubber member and the outer rotor. The rubber member, thus, presses the resin member into constant abutment with the peripheral surface of the outer rotor to hermetically seal between the low-pressure region and the high-pressure region.

In recent years, there has been an increasing demand for the pump to discharge brake fluid at high pressure. The above described conventional sealing mechanisms, however, need to have a large clearance between the casing and the outer rotor for meeting a pressure requirement because of design limitations in terms of production tolerance of the pump. It is, therefore, impossible for the pump to have the required endurance against the discharge of the brake fluid at high pressure. For instance, the resin member may deform into the clearance between the casing and the outer rotor, thereby resulting in breakage of the resin member, which leads to a lack of sealing ability of the sealing mechanism. Usually, the resin member is easy to deform, especially, at high temperature and high pressure, thereby facilitating the deformation thereof into the clearance between the casing and the outer rotor. It is, thus, difficult to ensure the durability of the sealing mechanisms and achieve the discharging of the brake fluid at high pressure.

SUMMARY OF THE INVENTION

It is therefore an object of this disclosure to provide an improved structure of a rotating pump designed to ensure a required degree of hermetic sealing and capable of discharging fluid at high pressure.

According to one aspect of the invention, there is provided a rotating pump which may be employed in a brake system for automotive vehicles. The rotating pump comprises: (a) a drive shaft; (b) a rotor assembly made up of an outer rotor and an inner rotor, the outer rotor having inner teeth formed on an inner periphery thereof, the inner rotor having outer teeth formed on an outer periphery thereof and being rotated by the drive shaft around an axis defined by the drive shaft, the outer teeth meshing with the inner teeth of the outer rotor to define a plurality of cavities; (c) a casing in which the drive shaft is installed, the casing including a rotor chamber in which the rotor assembly is mounted to be rotatable with a gap formed between an inner peripheral surface of the casing which faces the outer rotor and an outer peripheral surface of the outer rotor, the casing having an inlet port from which fluid is sucked into the rotor assembly and an outlet port from which the fluid is discharged with rotation of the rotor assembly; (d) a first and a second recess formed in the inner peripheral surface of the casing which is exposed to the gap; and (f) a first and a second sealing member which are disposed in the first and second recesses, respectively, to define within the gap a low-pressure region leading to the inlet port and a high-pressure region leading to the outlet port. Each of the first and second sealing members is made up of a seal functioning portion and an elastically pressing portion. The seal functioning portion is placed in contact with the outer periphery of the outer rotor and a low-pressure side surface that is a portion of an inner wall surface of a corresponding one of the first and second recesses which is closer to the low-pressure region than to the high-pressure region to establish a difference in pressure between the low-pressure region and the high-pressure region. The elastically pressing portion is located closer to a bottom of a corresponding one of the first and second recesses than the seal functioning portion is and works to press the seal functioning portion against the outer periphery of the outer rotor. The seal functioning portion includes a resinous member and a deformation-suppressing member. The resinous member is placed in contact with the outer periphery of the outer rotor and the low-pressure side surface of the inner wall surface of a corresponding one of the first and second recesses to establish the difference in pressure between the low-pressure region and the high-pressure region. The deformation-suppressing member is made of material which is more rigid than that of the resinous member and located closer to the low-pressure region than the resinous member is. A boundary between a surface of the deformation-suppressing member which faces the low-pressure side surface and a surface of the resinous member which faces the low-pressure side surface is located inside a corresponding one of the recesses.

The first and second sealing members are, as described above, installed in the casing to hermetically isolate between the low-pressure region and the high-pressure region in the gap. Specifically, the seal functioning portion of each of the first and second sealing members is pressed by an elastically reactive force, as produced by the elastically pressing portion, and the high pressure of the fluid in the gap toward the low-pressure region in the gap, thereby bringing the resinous member into constant abutment with the inner wall of a corresponding of the first and second recesses in addition to the outer periphery of the outer rotor and an inner wall of the casing to establish a hermetic seal between the high-pressure region and the low-pressure region in the gap.

The resinous member is pressed by the high pressure of the fluid, but stopped by the deformation-suppressing member of the seal functioning portion from being deformed into the low-pressure region of the gap, thereby minimizing the risk of breakage of the resinous member to ensure the stability of sealing the gap. This enables the rotating pump to discharge the fluid at an increased pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood more fully from the detailed description given hereinbelow and from the accompanying drawings of the preferred embodiments of the invention, which, however, should not be taken to limit the invention to the specific embodiments but are for the purpose of explanation and understanding only.

In the drawings:

FIG. 1 is a circuit diagram which illustrates a brake system equipped with a rotating pump according to the first embodiment of the invention;

FIG. 2 is a partially sectional view which illustrates an internal structure of the rotating pump of FIG. 1;

FIG. 3(
a) is an enlarged view of a sealing member shown in FIG. 2;

FIG. 3(
b) is an illustration which shows a seal functioning portion of a sealing member, as viewed in an axial direction of a drive shaft of the rotating pump of FIG. 2;

FIG. 3(
c) is an illustration of the seal functioning portion of FIG. 3(b), as viewed from the center of the rotating pump in a radius direction of the drive shaft;

FIG. 4 is an illustration which shows layout of the sealing member shown in FIG. 2, as viewed from the center of the rotating pump in a radius direction of a drive shaft of the rotating pump;

FIG. 5 is an illustration which shows a first modification of a sealing member, as viewed in an axial direction of a drive shaft of the rotating pump of FIG. 2;

FIG. 6 is an illustration which shows a second modification of a sealing member, as viewed in an axial direction of a drive shaft of the rotating pump of FIG. 2;

FIG. 7 is an illustration which shows a third modification of a sealing member, as viewed in an axial direction of a drive shaft of the rotating pump of FIG. 2;

FIG. 8(
a) is an illustration which shows a first modification of a joining structure of a resinous member and a deformation-suppressing member of a sealing member, as viewed in an axial direction of a drive shaft of the rotating pump of FIG. 2;

FIG. 8(
b) is a sectional illustration of the joining structure in FIG. 8(a), as viewed from the center of the rotating pump in a radius direction of the drive shaft;

FIG. 9(
a) is an illustration which shows a second modification of a joining structure of a resinous member and a deformation-suppressing member of a sealing member, as viewed in an axial direction of a drive shaft of the rotating pump of FIG. 2;

FIG. 9(
b) is a sectional illustration of the joining structure in FIG. 9(a), as viewed in a radius direction of the drive shaft;

FIG. 10(
a) is an illustration which shows a third modification of a joining structure of a resinous member and a deformation-suppressing member of a sealing member, as viewed in an axial direction of a drive shaft of the rotating pump of FIG. 2;

FIG. 10(
b) is a sectional illustration of the joining structure in FIG. 10(a), as viewed in a radius direction of the drive shaft; and

FIG. 11 is an illustration which shows a fourth modification of a joining structure of a resinous member and a deformation-suppressing member of a sealing member, as viewed in an axial direction of a drive shaft of the rotating pump of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments will be described below with reference to the drawings wherein like reference numbers refer to like or equivalent parts in several views.

First Embodiment

Referring to FIG. 1, there is shown an automotive brake system equipped with a rotating pump that is a part of a hydraulic circuit of the brake system. The brake system, as referred to herein, is designed as a so-called diagonal split system which includes two brake hydraulic circuits one of which controls the right front and the left rear wheel and the other of which controls the left front and the right rear wheel, but may be engineered as a front/rear split system.

The brake system is equipped with a brake pedal 1 (i.e., a brake actuating member) to be depressed by a vehicle occupant or driver for applying the brakes to the vehicle, a brake booster 12, a master cylinder 3, wheel cylinders 4 and 5, and a brake pressure control actuator 6. The master cylinder 3, as will be described later in detail, works to produce a braking hydraulic pressure in response to an operation of the brake actuating member (i.e., the brake pedal 1).

The brake pedal 1 is connected to the brake booster 2 and the master cylinder 3. When the driver of the vehicle depresses the brake pedal 1, the brake booster 2 works to boost the pressure applied to the brake pedal 1. Specifically, the brake booster 2 is equipped with a push rod which works to push master pistons installed in the master cylinder 3, thereby developing the pressure (which will also be referred to as M/C pressure below).

To the master cylinder 3, a master reservoir 3a is connected which stores therein an excess of the brake fluid in the master cylinder 3.

The M/C pressure is transmitted to the front right wheel cylinder 4 and the rear left wheel cylinder 5 as wheel cylinder (W/C) pressure. The brake pressure control actuator 6 is disposed between the master cylinder 3 and the wheel cylinders 4 and 5 and works to control the W/C pressure, as developed in each of the wheel cylinders 4 and 5.

The brake pressure control actuator 6 includes a first hydraulic circuit and a second hydraulic circuit. The first hydraulic circuit is a hydraulic circuit working to control the brake fluid to be applied to the front right wheel FR (i.e., the wheel cylinder 4) and the left rear wheel RL (i.e., the wheel cylinder 5). The second hydraulic circuit is a hydraulic circuit working to control the brake fluid to be applied to the left front wheel FL and the right rear wheel RR. The first hydraulic circuit and the second hydraulic circuit are substantially identical in structure with each other. The following discussion will refer only to the first hydraulic circuit for the brevity of disclosure.

The brake system (i.e., the first hydraulic circuit) is equipped with a main hydraulic line A (also called a main hydraulic path below) connecting with the master cylinder 3. The main hydraulic line A has disposed therein a differential pressure control valve 7 which divides the main hydraulic line A into two: a pipe line A1 which is a hydraulic line extending from the master cylinder 3 to the differential pressure control valve 7 and subjected to the M/C pressure and a pipe line A2 which is a hydraulic line extending from the differential pressure control valve 7 to the wheel cylinders 4 and 5.

The differential pressure control valve 7 is operable in either of two modes: an open mode and a pressure-difference mode. In a normal braking mode where it is required to produce the braking force as a function of an amount of depression of the brake pedal 11 by the driver, the valve position of the differential pressure control valve 7 is placed in the open mode. When the valve position of the differential pressure control valve 7 is placed in the pressure-difference mode, the differential pressure control valve 7 works to control the flow of the braking fluid to elevate and hold the W/C pressures above the M/C pressure by a pressure difference, as developed by the differential pressure control valve 7.

The pipe line A2 includes two branch lines: one being equipped with a pressure-increasing valve 8a which increases the pressure of the brake fluid supplied to the wheel cylinder 4, and one being equipped with a pressure-increasing valve 8b which increases the pressure of the brake fluid supplied to the wheel cylinder 5.

Each of the pressure-increasing valves 8a and 8b is implemented by a two-position valve which is opened or closed by a brake electronic control unit (ECU), not shown, to control increasing of the braking hydraulic pressure (i.e., the pressure of the brake fluid applied to the wheel cylinder 4 or 5). Specifically, when the pressure-increasing valve 8a is opened, the pressure of the brake fluid, as created by the M/C pressure, is transmitted to the wheel cylinder 4. In a normal braking mode where brake fluid pressure control, such as an anti-lock brake control, is not executed, the pressure-increasing valve 8a is opened. The same is true for the pressure-increasing valve 8b.

The brake pressure control actuator 6 also includes a hydraulic line B which extends as a pressure-reducing path between a pressure control reservoir 9 and a junction of the pressure-increasing valve 8a and the wheel cylinder 4 and between the pressure control reservoir 9 and a junction of the pressure-increasing valve 8b and the wheel cylinder 5. The brake fluid is drained to the pressure control reservoir 9 through the hydraulic line B to control the W/C pressure exerted on the wheel cylinders 4 and 5 to prevent the wheels of the vehicle from locking.

The hydraulic line B is equipped with pressure-reducing valves 10a and 10b which are each implemented by a two-position solenoid valve. The pressure-reducing valves 10a and 10b are opened or closed by the brake ECU to control decreasing of the braking hydraulic pressure (i.e., the pressure of the brake fluid applied to the wheel cylinder 4 or 5). In the normal braking mode where the brake fluid pressure control is not executed, the pressure-reducing valves 10a and 10b are kept closed. When it is required to drain the brake fluid to the pressure control reservoir 9, the pressure-reducing valves 10a and 10b are opened.

The brake pressure control actuator 6 also includes a hydraulic line C which extends between the pressure control reservoir 9 and the hydraulic line A. The hydraulic line C is equipped with a pump 11 which is disposed between a junction of the differential pressure control valve 7 and the pressure-increasing valves 8a and 8b and driven by an electric motor 12. The hydraulic line C also has check valves 11a and 11b mounted across the pump 11.

The hydraulic line C is also equipped with an accumulator 13 disposed downstream of the pump 11 to alleviate pulsation of the brake fluid discharged from the pump 11. The brake pressure control actuator 6 also includes a hydraulic line D which extends as a sub-hydraulic line between the pressure control reservoir 9 and the master cylinder 3. The pump 11 works to suck the brake fluid from the hydraulic line A1 through the hydraulic line D and the pressure control reservoir 9 and output it to the hydraulic line A2 to elevate the W/C pressures.

The second hydraulic circuit, as already described, has the same structure as described above as that of the first hydraulic circuit. The control valves 7, 8a, 8b, 10a, and 10b, the rotating pump 11, the pressure control reservoir 9, and the motor 12 are installed in a housing which is drilled to define the above described hydraulic lines and constitute the brake pressure control actuator 6. The brake pressure control actuator 6 is, as described above, disposed between the master cylinder 3 and the wheel cylinders 4 and 4, thereby making the brake system, as illustrated in FIG. 1.

The brake system works to execute brake fluid pressure control tasks such as the ABS control, the brake assist control, the adaptive cruise control, and the regenerative braking control and drive the rotating pump 11 to suck or discharge the brake fluid. In recent years, it has been required to develop the high W/C pressure quickly; for example, in the brake assist control mode or the adaptive cruise control mode where it is necessary to actuate the rotating pump 11 to create a high pressure of brake fluid. The discharge pressure of the rotating pump 11 is, thus, required to be increased.

In order to meet the above requirement, the rotating pump 11 of this embodiment is engineered in the following way. The structure of the rotating pump 11 will be described in detail with reference to FIGS. 2, 3, and 4.

The rotating pump 11 is installed in a rotor chamber 50a of a casing 50. Specifically, within the rotor chamber 50a, an outer rotor 51 and an inner rotor 52 are arranged with center axes X and Y thereof being eccentric from each other. A combination of the outer rotor 51 and the inner rotor 52 works as a rotor assembly in the rotating pump 11.

The outer rotor 51 has inner teeth 51a formed on an inner periphery thereof. The inner rotor 52 has outer teeth 52a formed on an outer periphery thereof. The inner teeth 51a of the outer rotor 51 mesh with the outer teeth 52a of the inner rotor 52 so as to create a plurality of gaps or enclosed cavities 53 therebetween. More specifically, surfaces of the inner teeth 51a and the outer teeth 52a are placed in contact with each other to define the cavities 53. The outer rotor 51 and the inner rotor 52 are rotated by a drive shaft 54 arranged in the center of the inner rotor 52, so that the cavities 53 are changed in volume thereof with rotation of the drive shaft 54, thereby sucking or discharging the brake fluid.

The thus constructed rotating pump 11 is a multi-tooth trochoid pump with no crescent in which the inner teeth 51a of the outer rotor 51 and the outer teeth 52a of the inner rotor 52 mesh with each other to define the cavities 53. The meshing surfaces of the outer teeth 52a contact at a plurality of points with those of the inner teeth 51a to transmit torque from the inner rotor 52 to the outer rotor 51.

The casing 50 includes a center plate 50b and side plates 50c and 50d, as illustrated in FIG. 4. The center plate 50b embraces the outer peripheries of the rotors 51 and 52. The side plates 50c and 50d sandwich axially-opposed end surfaces of the rotors 51 and 52 and the center plate 50b. The center plate 50b and the side plates 50c and 50d form a space which defines the rotor chamber 50a. The side plates 50c and 50d have center holes (not shown) in which the drive shaft 54 is fit. The outer rotor 51 and the inner rotor 52 are disposed to be rotatable within the rotor chamber 50a. In other words, a rotatable assembly of the outer rotor 51 and the inner rotor 52 is arranged rotatably in the rotor chamber 50a of the casing 50, so that the outer rotor 51 may rotate about the axis X, and the inner rotor 52 may rotate about the axis Y. The axis Y is an axis of rotation of the inner rotor 52 defined by the drive shaft 54 (i.e., a longitudinal center line of the drive shaft 54).

If a line traversing perpendicular to the axes X and Y of the outer rotor 51 and the inner rotor 52 is, as illustrated in FIG. 2, defined as the center line Z of the rotating pump 11, the side plate 50c has an inlet port 60 and an outlet port 61 which are located on the left and right sides of the center line Z and communicate with the rotor chamber 50a. The inlet port 60 communicates with some of the cavities 53 through which the brake fluid is sucked into the pump 11. The outlet port 61 which communicates with some of the cavities 53 through which the brake fluid is discharged from the pump 11.

The enclosed cavity 53a that is one of the cavities 53 which has the greatest volume does not communicate with the inlet port 60 or with the outlet port 61. The cavity 53a works to develop a difference between the suction pressure in the inlet port 60 and the discharge pressure in the outlet port 61. One of the side plates 50c and 50d has a first flow path and a second flow path formed therein. The first flow path communicates between an annular gap S on the outer circumference of the outer rotor 51, that is, a clearance between the outer periphery of the outer rotor 51 and the inner wall of the casing 50 (i.e., the inner wall of the rotor chamber 50a) and the inlet port 60, while the second flow path communicates between the gap S and the outlet port 61. This creates a low-pressure region, as defined by a portion of the gap S, as will be described later in detail, communicating with the inlet port 60, and a high-pressure region, as defined by a portion of the gap S communicating with the outlet port 61. In practice, the gap S is, as can be seen in FIG. 2, blocked on the side of the outlet port 61.

The center plate 50b of the casing 50, as clearly illustrated in FIG. 2, has recesses 50e and 50f formed in the inner wall thereof. The recesses 50e and 50f will also be referred to as a first and a second recess below. Each of the recesses 50e and 50f is located at a given angle away from the center line Z toward the inlet port 60 around the axis Y (i.e., the rotating center) of the outer rotor 51. In other words, each of the recesses 50e and 50f lies on a circle, as defined about the axis Y, and is separate from the center line Z by the given angle. Sealing members 80 and 90 are mounted in the recesses 50e and 50f to stop the brake fluid from flowing within the gap S on the outer circumference of the outer rotor 51. In other words, the sealing members 80 and 90 are separate from each other in a circumferential direction of the outer rotor 51 through a portion of the gap S which faces and communicates with the inlet port 60. The sealing members 80 and 90 will also be referred to as a first and a second sealing member below.

The sealing members 80 and 90 work to hermetically isolate a high-pressure portion (i.e., the high-pressure region) and a low-pressure portion (i.e., the low-pressure region) of the gap S, thereby avoiding the flow of the brake fluid from the high-pressure region to the low-pressure region. In other words, the sealing members 80 and 90 serve to keep a portion of the gap S which communicates with the inlet port 60 at the suction pressure and a portion of the gap S which communicates with the outlet port 61 at the discharge pressure, thereby developing a balance in pressure between outside and inside the outer rotor 51. This prevents the outer rotor 51 from being pressed by the pressure of the brake fluid locally against the inner rotor 52 and the casing 50, thereby minimizing irregular wear of the teeth 51a and 52a and the outer periphery of the outer rotor 51.

FIGS. 3(
a) to 3(c) illustrate the structure of the sealing member 80 in detail. The sealing member 90 is identical in structure with the sealing member 80. The following discussion will, thus, refer only to the sealing member 80 for the sake of simplicity of explanation.

The sealing member 80 is, as can be seen in FIGS. 3(a) to 3(c), made up of two parts: a seal functioning portion 81 and an elastically pressing portion 82.

The seal functioning portion 81 is pressed against the circumferential surface of the outer rotor 51 and the side plates 50c and 50d to establish a hermetical seal in the gap S, that is, to seal between the high-pressure region and the low-pressure region. The seal functioning portion 81 is made up of a resinous block 81a and a deformation-suppressing block 8b. The seal functioning portion 81 is substantially of a pentagonal prism shape. The main part of the seal functioning portion 81 is made of the resinous block 81a, while the other part of the seal functioning portion 81 is made of the deformation-suppressing block 81b to define a surface of the seal functioning portion 81 exposed to the low-pressure region of the gap S. In other words, the deformation-suppressing block 81b is arranged so as to define a portion of the seal functioning portion 81 which is exposed to the low-pressure region of the gap S, while the resinous block 81a is shaped or located so as not to be exposed to the low-pressure region of the gap S.

The resinous block 81a is made of a soft resin such as Teflon (Trade Mark). The resinous block 81a is shaped to have outer surfaces contacting the outer circumference of the outer rotor 51 (see FIG. 3(a)), the side plates 50c and 50d (see FIG. 4), and the inner wall surface of the recess 50e, i.e., a portion (which will also be referred to as a low-pressure side surface below) of the inner wall of the recess 50e which is closer to the low-pressure side than to the high-pressure side in the gap S. The circumference (i.e., the outer peripheral surface) and the side surfaces of the deformation-suppressing block 81b are substantially entirely enclosed or surrounded by the surfaces of the recess 50e, the resinous block 81a, the side plates 50c and 50d, and the outer rotor 51, thereby hermetically isolating between the high-pressure region and the low-pressure region in the gap S to develop a desired difference in pressure between the high-pressure region and the low-pressure region. The resinous block 81a is shaped to have a dimension (i.e., length L₁in FIG. 4) in the same direction as the axial direction of the outer rotor 51 (i.e., a direction parallel to the axis of rotation of the inner rotor 52) which is set greater than the thickness of the rotor chamber 50a in the axial direction of the outer rotor 51 (i.e., an interval between the side surfaces of the side plates 50c and 50d in a thickness-wise direction thereof). This causes the resinous block 81a, as indicated by a broken line in FIG. 4, to be elastically squeezed or deformed, so that the length (i.e., the dimension in the vertical direction in FIG. 4) of the resinous block 81a is decreased, thereby enhancing the ability to seal the gap S.

The resinous block 81a is also shaped to have the flat surface 81aa, as illustrated in FIGS. 3(a) and 3(b), which is diagonally opposed to the surface thereof with which the deformation-suppressing block 81b is placed in contact. The surface 81aa may be formed to extend substantially parallel to the surface the deformation-suppressing block 81b contacts. The elastically pressing portion 82 of the sealing member 80 is urged into abutment with the surface 81aa of the resinous block 81a.

The deformation-suppressing block 81b is made from material such as resin or metal which is more rigid than the resinous block 81a and works as a stopper to stop the resinous block 81a from elastically deforming toward the gap S. Specifically, the deformation-suppressing block 81b is located to be exposed to the low-pressure region of the gap S. In other words, the deformation-suppressing block 81b lies at a portion of the seal functioning portion 81 which is exposed to the low-pressure region of the gap S, so that the resinous block 81a is not exposed to the low-pressure region.

The deformation-suppressing block 81b is formed in the shape of a triangular prism made of two triangular bases and three side faces where the triangular bases are the end surfaces of the deformation-suppressing block 81b which face the side plates 50c and 50d, and the side faces are the side surfaces of the deformation-suppressing block 81b which extend in the axial direction of the outer rotor 51. The deformation-suppressing block 81b is dimensionally formed so that one of the side surfaces thereof partially faces or is partially exposed to the gap S, and a boundary 100, as illustrated in FIG. 3(a), between the one of the side surfaces and the surface of the resinous block 81a lies inside the recess 50e. The deformation-suppressing block 81b is also shaped to have a dimension (i.e., length L₂) in the same direction as the axial direction of the outer rotor 51 (i.e., a direction parallel to the axis of rotation of the inner rotor 52) which is, as can be seen from FIG. 4, set smaller than the thickness of the rotor chamber 50a in the axial direction of the outer rotor 51 (i.e., the minimum interval between the side surfaces of the side plates 50c and 50d ).

The resinous block 81a and the deformation-suppressing block 81b may be mechanically joined together or separate from each other. In this embodiment, they are joined together. Specifically, the resinous block 81a, as illustrated in FIG. 3(c), has a wedge-shaped recess 81ab formed in the surface thereof which diagonally faces the outer rotor 51. The wedge-shaped recess 81ab is shaped to have a depth, as can be seen from FIG. 3(b), substantially extending from the side of the low-pressure region to the side of the high-pressure region of the gap S. In other words, the wedge-shaped recess 81ab is recessed from the side of the low-pressure region to the side of the high-pressure region of the gap S. The deformation-suppressing block 81b is shaped to have a wedge-shaped protrusion 81ba formed on the surface thereof which faces the resinous block 81a. The wedge-shaped protrusion 81ba projects toward the high-pressure region of the gap S. The wedge-shaped protrusion 81ba is fit in the wedge-shaped recess 81ab to establish the joint of the resinous block 81a and the deformation-suppressing block 81b.

The seal functioning portion 81 is made up of the resinous block 81a and the deformation-suppressing block 81b in the above way.

The elastically pressing portion 82 is made of an elastically deformable material such as rubber and located deeper than the seal functioning portion 81 within the recess 50e, in other words, closer to the bottom of the recess 50e than the seal functioning portion 81 is. The elastically pressing portion 82 is elastically deformed within the recess 50e, thereby creating a reactive force which presses the resinous block 81a of the seal functioning portion 81 against the outer wall surface of the outer rotor 51 and the inner wall surface of the recess 50e. In other words, the elastically pressing portion 82 is elastically deformed between the inner wall surface of the recess 50e and the surface 81aa of the resinous block 81a of the seal functioning portion 81, thereby pressing the surface 81a a to urge the resinous block 81a against the inner wall of the recess 50e and the outer circumference of the outer rotor 51. This establishes a liquid-tight seal in the gap S, that is, hermetically blocks the gap S to isolate between the high-pressure region and the low-pressure region.

The operations of the brake system and the rotating pump 11 will be described below. For instance, when one of the above described brake fluid pressure control tasks is initiated, the control valves 7 and 30 to 33 are actuated according to the control mode, as specified by the one of the brake fluid pressure control tasks. Simultaneously, the motor 12 is actuated to suck and then discharge the brake fluid through the pump 11.

Specifically, when the motor 12 is actuated, the inner rotor 51 of the pump 11 is rotated by the drive shaft 54, thereby rotating the outer rotor 51 in the same direction as the inner rotor 51 through the meshing of the inner teeth 51a with the outer teeth 52a. The volumes of the cavities 53 are changed sequentially every rotation of the outer rotor 51 and the inner rotor 52, thereby sucking the brake fluid from the inlet port 60 and then discharge it from the outlet port 61 to the hydraulic line A2 to elevate the W/C pressure.

In the above way, the rotating pump 11 performs a normal pumping operation in which the rotors 51 and 52 are rotated to suck the brake fluid from the inlet port 60 and then discharge it from the outlet port 61. During the normal pumping operation, a portion of the gap S on the outer circumference of the outer rotor 51 communicating with the inlet port 60 is kept at the suction pressure, while a portion of the gap S communicating with the outlet port 61 is kept at the discharge pressure. This creates, as described above, the low-pressure region and the high-pressure region in the gap S.

The sealing members 80 and 90 are, as described above, installed in the center plate 50b of the casing 50 to hermetically isolate between the low-pressure region and the high-pressure region in the gap S. Specifically, the seal functioning portion 81 of each of the sealing members 80 and 90 is pressed by the elastically reactive force, as produced by the elastically pressing portion 82, and the high pressure of the brake fluid in the gap S toward the low-pressure region in the gap S, thereby bringing the resinous block 81a into constant abutment with the inner wall of the recess 50e in addition to the outer circumferential surface of the outer rotor 51 and the surfaces of the side plates 50c and 50d to establish the hermetic seal between the high-pressure region and the low-pressure region in the gap S.

The resinous block 81a is pressed by the high pressure of the brake fluid, but stopped by the deformation-suppressing block 81b of the seal functioning portion 81 from being deformed into the low-pressure region of the gap S, thereby minimizing the risk of breakage of the resinous block 81a to ensure the stability of sealing the gap S. This enables the rotating pump 11 to discharge the brake fluid at an increased pressure.

Other Embodiments

While the present invention has been disclosed in terms of the preferred embodiment in order to facilitate better understanding thereof, it should be appreciated that the invention can be embodied in various ways without departing from the principle of the invention.

For instance, the seal functioning portion 81 of each of the sealing members 80 and 90 may be engineered to have the resinous block 81a and the deformation-suppressing block 81b which are mechanically separate from each other. In this case, it is also advisable that at least the boundary 100 between one of the side surfaces of the deformation-suppressing block 81b which is exposed to the low-pressure region of the gap S and the surface of the resinous block 81a which faces in the same direction as the one of the side surfaces of the deformation-suppressing block 81b be located fully within a corresponding one of the recesses 50e and 50f.

The deformation-suppressing block 81b may be, as illustrated in FIG. 6, formed in the shape of a circular cylinder made of two circular bases and a side face substantially perpendicular to the circular bases where the circular bases are the end surfaces of the deformation-suppressing block 81b which face the side plates 50c and 50d, and the side face is the side surface of the deformation-suppressing block 81b which extends in the axial direction of the outer rotor 51. In this case, when the rotating pump 11 is at rest in operation, the resinous block 81a is located far away from the deformation-suppressing block 81b on a portion of the inner surface of, for example, the recess 50e which is closer to the low-pressure region than to the high-pressure region of the gap S, thus facilitating the ease of elastic deformation of the resinous block 81a into the gap S. This problem, however, may be alleviated by making the deformation-suppressing block 81b to have a radius greater than the thickness of the gap S (i.e., the dimension of the gap S in the radius direction of the outer rotor 50). In other words, it is advisable that the deformation-suppressing block 81b be shaped so that a boundary between the resinous block 81a and the deformation-suppressing block 81b on a portion of the inner wall of, for example, the recess 50e which is closer to the low-pressure region than to the high-pressure region fully lies, like in the first embodiment, inside the recess 50e when the resinous block 81a is deformed most greatly. The same applies to the case where the deformation-suppressing block 81b is of a shape other than the triangular prism or the circular cylinder. Specifically, the deformation of the resinous block 81a into the gap S is avoided by making the deformation-suppressing block 81b to have a dimension greater than that of the gap S in the radius direction of the drive shaft 54 (i.e., the outer rotor 51) so that the deformation-suppressing block 81b is at least partially placed in contact with the inner wall of the recess 50e.

The deformation-suppressing block 81b may alternatively be, as illustrated in FIG. 7, formed in the shape of a quadrangular prism made of two square or rectangular bases and four side faces substantially perpendicular to the rectangular bases where the rectangular bases are the end surfaces of the deformation-suppressing block 81b which face the side plates 50c and 50d, and the side faces are the side surfaces of the deformation-suppressing block 81b which extend in the axial direction of the outer rotor 51.

The jointing of the resinous block 81a and the deformation-suppressing block 81b of the seal functioning portion 81 may be changed from the one, as illustrated in FIGS. 3(b) and 3(c). The following discussion will refer to the case where the deformation-suppressing block 81b is, as illustrated in FIG. 7, of a quadrangular prism shape, but however, the same joining structure as described below may be used in the case where the deformation-suppressing block 81b is substantially of a triangular prism shape, as illustrated in FIG. 5, or a circular cylindrical shape, as illustrated in FIG. 6.

Specifically, the resinous block 81a, as illustrated in FIGS. 8(a) and 8(b), has formed on the surface thereof a protrusion 81ac which projects toward the low-pressure region of the gap S. The deformation-suppressing block 81b is shaped to have a recess 81bb which is shaped to have a depth, as can be seen from FIG. 8(b), substantially extending from the side of the high-pressure region to the side of the low-pressure region of the gap S. In other words, the recess 81bb is recessed from the side of the high-pressure region to the side of the low-pressure region of the gap S. The protrusion 81ac is fit in the recess 81bb to establish the mechanical joint between the resinous block 81a and the deformation-suppressing block 81b.

The jointing of the resinous block 81a and the deformation-suppressing block 81b of the seal functioning portion 81 may alternatively be established in the way, as illustrated in FIGS. 9(a) and 9(b). Specifically, the deformation-suppressing block 81b has a protrusion 81ba formed on two of the side surfaces thereof which face the resinous block 81a (i.e., the side surfaces of the deformation-suppressing block 81b which contact the resinous block 81a ) The protrusion 81ba is of a U-shaped in traverse cross section and extends from the corner of the deformation-suppressing block 81b which faces the outer rotor 51 to the corner of the deformation-suppressing block 81b which faces a portion of the inner wall of the recess 50e which is closer to the low-pressure region of the gap S. The resinous block 81a has formed therein a recess or groove 81ab which extends from the surface thereof which faces the outer rotor 51 and to the surface thereof which faces the portion of the inner wall of the recess 50e which is closer to the low-pressure region of the gap S. In other words, the groove 81ab is formed in the surface of the resinous block 81a which faces the deformation-suppressing block 81b. The groove 81ab is of a U-shaped in traverse cross section. The protrusion 81ba of the deformation-suppressing block 81b is fit in the groove 81ab of the resinous block 81a to establish the mechanical joining of the resinous block 81a and the deformation-suppressing block 81b.

The jointing of the resinous block 81a and the deformation-suppressing block 81b of the seal functioning portion 81 may alternatively be established, as illustrated in FIG. 11, by embedding at least a portion of the deformation-suppressing block 81b in the resinous block 81a. In other words, the side surface of the resinous block 81a which faces the deformation-suppressing block 81b is partially wrapped around the side surfaces of the deformation-suppressing block 81b to establish the mechanical joint between the resinous block 81a and the deformation-suppressing block 81b.

ROTATING PUMP

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