Rotary pump with better fluid sealing structure and brake apparatus having same

In the rotary pump, a sealing member is provided at a clearance between a casing and axial end surfaces of the inner and outer rotors, the sealing member extending from an outer circumference of the outer rotor, via the inner rotor between a drive shaft and a discharge port, to another circumference of the outer rotor so that brake fluid communication from the discharge port to an intake port may be prevented, but the brake fluid communication between the outer circumference of the outer rotor and almost all of teeth gap portions on a discharge port side and, further, between almost all of teeth gap portions on an intake port side and a clearance between the drive shaft and the inner rotor may be allowed.

CROSS REFERENCE TO RELATED APPLICATION
 This application is based upon and claims the benefit of priority of
 Japanese Patent Applications No. H.10-284227 filed on Oct. 6, 1998, No.
 H.10-284228 filed on Oct. 6, 1998, No. H.11-106911 filed on Apr. 14, 1999,
 and No. H. 11-224499 filed on Aug. 6, 1999, the contents of which are
 incorporated herein by reference.
 BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a rotary pump with better fluid sealing
 structure and a brake apparatus having the same. In particular, the
 present invention is preferably applied to an internal gear pump such as a
 trochoid pump or the like for brake apparatus for vehicles.
 2. Description of Related Art
 A rotary pump, for example, an internal gear pump, is comprised of a drive
 shaft to be driven by a motor, an inner rotor and an outer rotor to be
 rotated by the drive shaft and a casing for containing the drive shaft and
 the inner and outer rotors. The inner and outer rotors contained in the
 casing form a plurality of teeth gap portions constituted by inner teeth
 portions of the outer rotor and outer teeth portions of the inner rotor
 which are in mesh with each other. An intake port and a discharge port are
 disposed on opposite sides of a pump center line passing through the
 respective rotation axes of the inner and outer rotors.
 When the drive shaft is rotated for driving the pump, the inner rotor is
 rotated with the drive shaft with an axis of the drive shaft and,
 according to the rotation of the inner rotor, the outer rotor is rotated
 in a same direction as the inner teeth portions of the outer rotor are in
 mesh with the outer teeth portions of the inner rotor. As the respective
 volumes of the teeth gap portions between the inner and outer teeth
 portions are varied in every turn of the rotating inner and outer rotors,
 fluid is sucked from the intake port and discharged to the discharge port.
 In the pump mentioned above, there is a problem that the fluid is likely to
 leak from a high pressure side to a low pressure side through various
 clearances or gaps in the casing, since fluid pressure at the discharge
 port (hereinafter called discharge pressure) is higher than fluid pressure
 at the intake port (hereinafter called intake pressure) when the pump is
 driven.
 In more details, the high pressure fluid at the discharge port leaks to the
 low pressure intake port or a clearance between the drive shaft and the
 inner rotor through clearances between the casing and axial end surfaces
 of the inner and outer rotors, to the low pressure intake port through a
 clearance between the casing and an outer circumference of the outer rotor
 or to the low pressure intake port through teeth top gaps formed by
 forcing the meshed inner and outer teeth portions open.
 To cope with these problems, it is possible to narrow the clearance between
 the casing and the axial end surfaces of the inner and outer rotors or to
 diminish the clearance to such an extent that the casing and the axial end
 surfaces of the inner and outer rotors are always in direct contact with
 each other. However, even if the clearance is narrower, it is very
 difficult to prevent the fluid leakage and the extremely diminished
 clearance causes a mechanical loss due to the increased contact resistance
 with the casing.
 Further, it has been proposed to arrange a sealing member between the
 casing and all of the axial end surfaces of the rotors to restrain the
 fluid leakage. This is also likely to cause a mechanical loss due to the
 larger contact resistance with the sealing member.
 Furthermore, to prevent the fluid leakage from the outer circumference of
 the outer rotor, it has been proposed to arrange sealing member in
 recessed portions provided at an inner wall of the casing that faces the
 outer circumference of the outer rotor. However, it is very difficult to
 provide the thickness of the sealing member (the thickness in an axial
 direction of the inner and outer rotors) always equal to that of the
 casing because of manufacturing dimensional errors of the sealing member
 on the molding or machining processes thereof. If there exists a clearance
 between the casing and the sealing member due to the dimensional errors,
 fluid leaks through the clearance.
 SUMMARY OF THE INVENTION
 An object of the present invention is to provide a rotary pump having a
 better fluid sealing construction that the fluid leakage through the
 clearance between the casing and the axial end surfaces of the inner and
 outer rotors may be effectively prevented with a sealing member having a
 limited contact resistance with the casing and the rotors.
 Generally, the rotary pump is composed of an outer rotor provided with
 inner teeth at an inner circumference thereof, an inner rotor provided
 with outer teeth at an outer circumference thereof, the outer teeth being
 in mesh with the inner teeth so as to constitute a plurality of teeth gap
 portions therebetween, a drive shaft fitted to the inner rotor with a
 clearance between the drive shaft and the inner rotor for rotating the
 inner rotor together with the drive shaft, a casing provided with a rotor
 room where the inner and outer rotors are rotatably contained, a center
 bore communicating with the rotor room in which the drive shaft is
 rotatably housed and intake and discharge ports communicating respectively
 with the teeth gap portions, the rotor room having a first closed region
 between the intake and discharge ports on a side of the teeth gap portion
 whose volume is largest and a second closed region between the intake and
 discharge port on a side of the teeth gap portion whose volume is smallest
 and each of the first and second closed gap regions being operative for
 holding brake fluid pressure difference between the intake and discharge
 ports, wherein brake fluid is sucked from the intake port, being
 compressed through the teeth gap portions and discharged from the
 discharge port when the drive shaft is driven.
 To achieve the above object, in the rotary pump mentioned above, a
 transverse sealing member is provided at a transverse clearance between
 the casing and the axial end surfaces of the inner and outer rotors, the
 transverse sealing member extending from an outer circumference of the
 outer rotor, via the first closed region, the inner rotor between the
 drive shaft and the discharge port and the second closed region, to
 another circumference of the outer rotor so that brake fluid communication
 through the transverse clearance from the discharge port to the intake
 port may be prevented, but the brake fluid communication through the
 transverse clearance between the outer circumference of the outer rotor
 and almost all of the teeth gap portions on a side of the discharge port
 and, further, between almost all of the teeth gap portions on a side of
 the intake port and the clearance between the drive shaft and the inner
 rotor may be allowed.
 Further, it is preferable to provide the transverse sealing member in a
 manner that brake fluid communication through the transverse clearance
 between the outer circumference of the outer rotor and at least one of the
 teeth gap portions on the side of the intake port may be allowed.
 Furthermore, it is preferable that the casing is comprised of first and
 second side plates having respective center bores in which the drive shaft
 is housed and a center plate having a bore where the inner and outer rotor
 are contained, the center plate being put between the first and second
 plates for constituting the rotor room, wherein each of the first and
 second side plates is provided with grooved portion extending from the
 outer circumference of the outer rotor, via the first closed region, the
 inner rotor between the drive shaft and the discharge port and the second
 closed region, to the other circumference of the outer rotor and the
 transverse sealing member is housed in each of the grooved portions.
 Preferably, the inner and outer rotors are arranged to be in mesh with each
 other so that brake fluid in the teeth gap portion or teeth gap portions
 falling within the first closed region may be compressed. As a result,
 unusual frictional wear of the teeth of the inner and outer rotors may be
 prevented.
 As another aspect of the present invention, the rotary pump has a sealing
 member by which the fluid leakage through the clearance between the casing
 and the outer circumference surface of the outer rotor may be effectively
 prevented.
 To achieve the another aspect of the present invention in the rotary pump
 mentioned above, an inner wall of the bore of the center plate facing the
 outer circumference of the outer rotor is provided with two recessed
 portions and a lateral sealing member is housed in each of the recessed
 portions for preventing brake fluid communication from the discharge port
 side to the intake port side in the outer circumference of the outer
 rotor. The lateral sealing member has a portion whose length in an axial
 direction of the drive shaft is larger than the thickness of the center
 plate before the lateral sealing member is put and loaded by the
 transverse sealing member or directly by the first and second side plates.
 Preferably, the two recessed portions are located on the intake port side
 with respect to a hypothetical line connecting a center of the first
 closed region and a center of the second closed region.
 It is a further aspect of the present invention to provide detail
 structures of the transverse sealing members and the lateral sealing
 members that can effectively prevent the brake fluid leakage from the
 discharge port side to the intake port side through the respective
 clearances mentioned above.
 To this end, the transverse sealing member is comprised of a first element
 made of elastic material and arranged on a bottom side of the grooved
 portion and a second element arranged on an opening side of the grooved
 portion. The second element is in closed contact with the inner and outer
 rotor by means of elastic force of the first element so that the sealing
 function of the transverse sealing member may be ensured.
 Further, it is preferable that the grooved portion is shaped a ring that is
 off-centered with respect to an axis of the drive shaft, the first element
 is an o-ring and the second element is a resin ring. As a result, the
 transverse sealing member is in contact only with limited parts of the
 inner and outer rotors for sealing.
 Furthermore, an area of a surface of the second element actually in contact
 with the inner rotor is smaller than that of the surface being pressed by
 the first element for diminish the contact resistance.
 In particular, the surface in contact with the inner rotor is provided with
 a step portion that the surface of the second element is stepped. The
 second element hangs over the teeth gap portions on the discharge port
 side with a clearance between the step portion and the teeth gap portions
 in a direction perpendicular to the drive shaft so that the teeth gap
 portions on the discharge port side may communicate with the outer
 circumference of the outer rotor on the discharge port side.
 On the other hand, the lateral sealing member is comprised of an elastic
 element arranged on a bottom side of the recessed portion and a resin
 element on an opening side of the recessed portion. A length of the resin
 element in an axial direction of the drive shaft is larger than the
 thickness of the center plate before the resin element is put between and
 loaded by the transverse sealing members.
 Preferably, the resin element may have a tapered surface at a corner
 thereof on a bottom side of the recessed portion and on the discharge port
 side and the elastic element may be arranged between the tapered surface
 and the recessed portion.
 It is a final object of the present invention to provide a brake apparatus
 having a hydraulic circuit in which the rotary pump described above is
 applied. The rotary pump is used for increasing fluid pressure to wheel
 cylinders in the hydraulic circuit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 A first embodiment of the present invention is described with reference to
 FIGS. 1, 2A and 2B.
 FIG. 1 shows an outline structure of a brake apparatus to which a trochoid
 pump as a rotary pump is applied. The basic composition of the brake
 apparatus will be described with reference to FIG. 1. In this embodiment,
 a brake apparatus is applied to a vehicle provided with a hydraulic
 circuit of a diagonal conduit system having a first conduit connecting
 wheel cylinders of a front right wheel and a rear left wheel and a second
 conduit connecting wheel cylinders of a front left wheel and a rear right
 wheel. The vehicle is a four wheel vehicle of front wheel drive.
 As shown in FIG. 1, a brake pedal 1 is connected to a booster 2. The
 booster 2 boosts brake depression force.
 Further, the booster 2 is provided with a rod for transmitting boosted
 depression force to a master cylinder 3. In detail, the master cylinder 3
 generates master cylinder pressure when the rod pushes a master piston
 arranged in the master cylinder 3. The brake pedal 1, the booster 2 and
 the master cylinder 3 correspond to a brake fluid pressure generating
 device.
 The master cylinder 3 is provided with a master reservoir 3a for supplying
 brake fluid into the master cylinder 3 or storing extra brake fluid of the
 master cylinder 3.
 Further, the master cylinder pressure is transmitted to a wheel cylinder 4
 for a front right wheel (FR) and a wheel cylinder 5 for a rear left wheel
 (RL) via a brake assist system provided with a function of an antilock
 brake system (hereinafter, referred to as ABS). In the following
 explanation, the brake apparatus will be described with respect to the
 hydraulic circuit in the first conduit connecting the wheel cylinders of a
 front right wheel (FR) and a rear left wheel (RL). The explanation for the
 second conduit connecting the wheel cylinders of a front left wheel (FL)
 and a rear right wheel (RR) will be omitted since the hydraulic circuit in
 the second conduit is quite similar to that in the first conduit.
 The brake apparatus is provided with a conduit (main conduit) A connected
 to the master cylinder 3. A proportioning valve (PV) 22 is disposed in the
 main conduit A. The main conduit A is divided into two portions by the
 proportioning valve 22. That is, the main conduit A is divided into a
 first conduit A1 from the master cylinder 3 to the proportioning valve 22
 and a second conduit A2 from the proportioning valve 22 to the respective
 wheel cylinders 4 and 5.
 The proportioning valve 22 has a function of transmitting a reference
 pressure of a brake fluid to the downstream side with a predetermined
 attenuation rate when the braking fluid flows in the positive direction
 (in this embodiment, a direction from the side of the wheel cylinder to
 the side of the master cylinder is the positive direction). That is, by
 inversely connecting the proportioning valve 22 as shown in FIG. 1,
 pressure of the brake fluid on the side of the second conduit A2 becomes
 the reference pressure.
 Further, the second conduit A2 branches out two conduits. A pressure
 increasing control valve 30 for controlling an increase of brake fluid
 pressure of the wheel cylinder 4 is installed to one of the branched
 conduits and a pressure increasing control valve 31 for controlling an
 increase of brake fluid pressure of the wheel cylinder 5 is installed to
 the other thereof.
 The pressure increasing control valve 30 and 31 is a two-position valve
 capable of controlling communicating and shut-off states by an electronic
 control unit (hereinafter, referred to as ECU). When the two-position
 valve is controlled to a communicating state, the master cylinder pressure
 or the brake fluid pressure produced by a pump 10 can be applied to the
 respective wheel cylinders 4 and 5.
 In the normal braking operation where ABS is not controlled by the ECU as
 in the case where pressure reduction of the wheel cylinder pressure is not
 carried out, the pressure increasing control valves 30 and 31 are always
 controlled in the communicating state. Safety valves 30a and 31a are
 installed in parallel with the pressure increasing control valves 30 and
 31, respectively. The safety valve 30a, 31a allows the brake fluid to
 swiftly return from the wheel cylinder 4, 5 to the master cylinder 3 when
 ABS control has been finished by stopping depression of the brake pedal 1.
 A pressure reducing control valve 32, 33 capable of controlling
 communicating and shut-off states by the ECU is arranged at conduits B
 connecting the second conduit A2 between the pressure increasing control
 valve 30, 31 and the wheel cylinder 4, 5, and a reservoir port 20a of a
 reservoir 20. In the normal braking operation, the pressure reducing
 control valves 32 and 33 are always brought into a cut-off state.
 A rotary pump 10 is arranged at a conduit C connecting the reservoir hole
 20a of the reservoir 20 and the second conduit A2 between the
 proportioning valve 22 and the pressure increasing control valves 30 and
 31. Safety valves 10a and 10b are disposed in the conduit C on both sides
 of the rotary pump 10. A motor 11 is connected to the rotary pump 10 to
 drive the rotary pump 10. A detailed explanation of the rotary pump 10
 will be given later.
 A damper 12 is arranged on the discharge side of the rotary pump 10 in the
 conduit C to alleviate pulsation of the brake fluid delivered by the
 rotary pump 10. An auxiliary conduit D is installed to connect the conduit
 C between the reservoir 20 and the rotary pump 10, and the master cylinder
 3. The rotary pump 10 sucks the brake fluid of the first conduit A1 via
 the auxiliary conduit D and discharges it to the second conduit A2,
 whereby the brake fluid pressures of the wheel cylinders 4 and 5 are made
 higher than the master cylinder pressure. As a result, wheel braking
 forces of the wheel cylinders 4 and 5 are increased. The proportioning
 valve 22 works to hold the pressure difference between the master cylinder
 pressure and the wheel cylinder pressure.
 A control valve 34 is installed in the auxiliary conduit D. The control
 valve 34 is always brought into a cut-off state in the normal braking
 operation.
 A check valve 21 is arranged between a connection point of the conduit C
 and the auxiliary conduit D and the reservoir 20 to prevent the brake
 fluid drawn via the auxiliary conduit D from flowing in a reverse
 direction to the reservoir 20.
 A control valve 40 is disposed between the proportioning valve 22 and the
 pressure increasing control valves 30 and 31 in the second conduit A2. The
 control valve 40 is normally controlled in a communicating state. However,
 the control valve 40 is switched to a differential pressure producing
 state to hold the pressure difference between the master cylinder pressure
 and the wheel cylinder pressure, when the vehicle is braked in panic or
 traction control (TRC) is carried out so that the brake fluid pressure of
 the wheel cylinders 4 and 5 may be controlled to become higher than the
 master cylinder pressure.
 FIG. 2A shows a sectional view of the rotary pump 10. FIG. 2B shows a
 sectional view taken along a line IIB--IIB of FIG. 2 A. First, the
 structure of the rotary pump 10 will be described with reference to FIGS.
 2A and 2B.
 An outer rotor 51 and an inner rotor 52 are contained in a rotor room 50a
 of the casing 50 of the rotary pump 10. The outer rotor 51 and the inner
 rotor 52 are assembled in the casing 50 in a state where respective centre
 axes (point X and point Y in the drawing) are shifted from each other. The
 outer rotor 51 is provided with an inner teeth portion 51a at its inner
 periphery. The inner rotor 52 is provided with an outer teeth portion 52a
 at its outer periphery. The inner teeth portion 51a of the outer rotor 51
 and the outer teeth portion 52a of the inner rotor 52 are in mesh with
 each other and form a plurality of teeth gap portions 53. As is apparent
 from FIG. 2A, the rotary pump 10 is a multiple teeth trochoid type pump
 having no partition plates (crescent) in which the teeth gap portions 53
 are formed by the inner teeth portion 51a of the outer rotor 51 and the
 outer teeth portion 52a of the inner rotor 52. The inner rotor 52 and the
 outer rotor 51 share a plurality of contact points (that is, contact
 faces) at the mesh faces in order to transmit rotation torque of the inner
 rotor 52 to the outer rotor 51.
 As shown in FIG. 2B, the casing 50 is composed of a first side plate 71 and
 a second side plate 72 that are placed on opposite sides of the outer and
 inner rotors 51 and 52, and a center plate 73 placed between the first
 side plate 71 and a second side plate 72. The center plate 73 is provided
 with a bore in which the outer and inner rotors 51 and 52 are housed. The
 first and second side plates 71 and 72 and the center plate 73 constitute
 the rotor room 50a.
 The first and second side plates 71 and 72 are respectively provided at
 their center portions with center bores 71a and 72a which communicate with
 the rotor room 50a. The drive shaft 54 fitted to the inner rotor 52 is
 housed in the center bores 71a and 72a. The outer rotor 51 and the inner
 rotor 52 are rotatably arranged in the bore of the center plate 73. That
 is, a rotating unit constituted by the outer rotor 51 and the inner rotor
 52 is rotatably contained in the rotor room 50a of the casing 50. The
 outer rotor 51 rotates with a point X as a rotation axis and the inner
 rotor 52 rotates with a point Y as a rotation axis.
 When a line running on both point X and point Y respectively corresponding
 to the rotation axes of the outer rotor 51 and the inner rotor 52 is
 defined as a center line Z of the rotary pump 10, the intake port 60 and
 the discharge port 61 both of which communicate with the rotor room 50a
 are formed on the left and right sides of the center line Z in the first
 and second side plates 71 and 72. The intake port 60 and the discharge
 port 61 are arranged respectively at positions communicating with a
 plurality of teeth gap portions 53. The brake fluid from outside can be
 sucked into the teeth gap portions 53 via the intake port 60 and the brake
 fluid in the teeth gap portions 53 can be discharged to outside via the
 discharge port 61.
 There exist a maximum volume teeth gap portion where the brake fluid volume
 is the largest and a minimum volume teeth gap portion where the brake
 fluid volume is the smallest among the plurality of the teeth gap portions
 53. The rotor room 50a is provided, between the intake and discharge ports
 60 and 61, with first and second closed regions 53a and 53b respectively
 located on the sides of the maximum and minimum volume teeth gap portions
 and communicated neither with the intake port 60 nor with the discharge
 port 61. The first and second closed regions 53a and 53b serve to hold
 pressure difference between the intake pressure at the intake port 60 and
 the discharge pressure at the discharge port 61.
 The first and second side plates 71 and 72 and the center plate 73 are
 provided respectively with a communicating path 73a for communicating the
 outer circumference of the outer rotor 51 with the intake port 60 and
 communicating paths 73b and 73c for communicating the outer circumference
 of the outer rotor 51 with the discharge port 61. The communicating path
 73a is arranged at a position advanced in a direction from the center line
 Z to the intake port 60 by an angle of about 90 degrees centering on the
 point X constituting the rotation axis of the outer rotor 51. The
 communicating path 73b is formed to communicate the teeth gap portion 53
 most adjacent to the first closed region 53a among the plurality of teeth
 gap portions 53 communicating with the discharge port 61 with the outer
 circumference of the outer rotor 51. The communicating path 73c is formed
 to communicate the teeth gap portion 53 most adjacent to the second closed
 region 53b among the plurality of teeth gap portions 53 communicating with
 the discharge port 61 with the outer periphery of the outer rotor 51.
 Specifically, the communicating paths 73b and 73c are arranged
 respectively at positions advanced in right and left directions from the
 center line Z to the discharge port 61 by an angle of about 22.5 degrees
 centering on the point X.
 Recessed portions 73d and 73e are formed on an inner wall of the bore of
 the center plate 73 at positions advanced in the left and right
 directions, respectively, from the center line Z to the intake port 60 by
 an angle of about 45 degrees centering on the point X constituting the
 rotation axis of the outer rotor 51. Lateral sealing members 80 and 81 are
 respectively installed in the recessed portions 73a and 73b to restrain
 the brake fluid from flowing in the outer circumference of the outer rotor
 51. In more detail, the lateral sealing members 80 and 81 are arranged
 respectively at intermediate points between the communicating paths 73a
 and 73b and between the communicating paths 73a and 73c. The lateral
 sealing member 80, 81 serves to separate, in the clearance between the
 outer rotor 51 and the bore of the center plate 73, a portion in which
 pressure of the brake fluid is low from a portion in which pressure of the
 brake fluid is high.
 The lateral sealing member 80, 81 is constituted by a spherical or
 cylindrical rubber element 80a, 81a and a rectangular shaped resin element
 80b, 81b. The resin element 80b, 81b is made of PTFE, PTFE containing
 carbon fiber or PTFE containing graphite. The resin element 80b, 81b is
 biased or pressed by the rubber element 80a, 81a to be brought into
 contact with the outer rotor 51. That is, as the dimensional deviation of
 the outer rotor 51 due to manufacturing errors or the like is inevitable,
 the rubber element 80a, 81a having elastic force can absorb the
 dimensional deviation.
 A width of the resin element 80b, 81b is shorter than that of the recessed
 portion 73d, 73e so that there may exist a gap to a certain extent in a
 rotating direction of the outer rotor 51 when the resin element 80b, 81b
 is housed in the recessed portion 73d, 73e. That is, in case that the
 width of the resin element 80b, 81b is equal to that of the recessed
 portion 73d, 73e, the resin element 80b, 81b is unlikely to go out of the
 recessed portion 73d, 73e, once the resin element 80b, 81b is pushed into
 the recessed portion 73d, 73e by pressurized brake fluid flow upon driving
 the pump. However, in case that the resin element 80b, 81b is housed with
 a gap to some degree in the recessed portion 73d, 73e so that the brake
 fluid may enter into on a side of the rubber element 80a, 81a with respect
 to the resin member 80b, 81b, the resin member 80b, 81b goes easily out of
 the recessed portion 73d, 73e as the pressure of the brake fluid acts back
 and forth on the resign element 80b, 81b.
 As shown in FIG. 2B, the first and second side plates 71 and 72 are
 provided respectively with grooved portions 71b and 72b. Each of the
 grooved portion 71b, 72b is shaped a ring surrounding the drive shaft 54,
 as shown in a two dots-dash line in FIG. 2A. In more detail, the center of
 the grooved portion 71b, 72b is positioned eccentrically on a side of the
 intake port 60(on a left side of the drawing) with respect to the axial
 center of the drive shaft 54. The grooved portion 71b, 72b passes through
 a portion between the discharge port 61 and the drive shaft 54, the first
 closed region 53a and the second closed region 53b and portions where the
 lateral sealing members 80 and 81 seal the outer circumference of the
 outer rotor 51.
 Transverse sealing members 100 and 101 are housed respectively in the
 grooved portions 71b and 72b. The transverse sealing member 100, 101 is
 composed of an o-ring 100a, 101a and a ring shaped resin element 100b,
 101b. The resin element 100b, 101b is arranged to be in contact with the
 inner rotor 52, the outer rotor 51 and the center plate 73 and, for
 performing the sealing function, biased by the o-ring 100a, 101a placed on
 a bottom side of the grooved portion 71b, 72b with respect to the resin
 element 100b, 101b. The resin element 100b, 101b is made of PEEK or PEEK
 containing carbon which is harder than material of the resin element 80b,
 81b.
 As mentioned above, the transverse sealing members 100 and 101 serve to
 seal the brake fluid communication between the high pressure discharge
 port 61 and the low pressure clearance between the drive shaft 54 and the
 inner rotor 52 or the low pressure intake port 60 through respective
 clearances between the axial end surfaces of the inner and outer rotors 52
 and 51 and the first and second side plates 71 and 72.
 To seal effectively the clearances between the axial end surfaces of the
 inner and outer rotors 52 and 51 and the first and second side plates 71
 and 72, it is essential that each of the transverse sealing members 100
 and 101 extends from the lateral sealing member 80 at the outer
 circumference of the outer rotor 51, via the first closed region 53a, a
 portion between the discharge port 61 and the drive shaft 54, the second
 closed region 53b, to the lateral sealing member 81 at the outer
 circumference of the outer rotor 51. As the transverse sealing member 100,
 101 seals only portions necessary for restraining the brake fluid leakage
 between high and low pressure portions and, therefore, is in minimum
 contact with the outer and inner rotors 51 and 52, the contact resistance
 of the transverse sealing member 100, 101 is smaller so that the
 mechanical loss may be limited.
 Next, an explanation will be given of operations of the brake apparatus and
 the rotary pump 10. The control valve 34 provided in the brake apparatus
 is pertinently brought into a communicating state when high pressure brake
 fluid needs to be supplied to the wheel cylinders 4 and 5, for example,
 when braking force in correspondence with depressing force of the brake
 pedal 1 cannot be obtained or when an operating amount of the braking
 pedal 1 is large. When the control valve 34 is switched to the
 communicating state, the master cylinder pressure generated by depressing
 the brake pedal 1 is applied to the rotary pump 10 via the auxiliary
 conduit D.
 In the rotary pump 10, the inner rotor 52 is rotated in accordance with
 rotation of the drive shaft 54 by driving the motor 11. In response to
 rotation of the inner rotor 52, the outer rotor 51 is also rotated in the
 same direction as the inner teeth portion 51a is in mesh with the outer
 teeth portion 52a. At this time, each volume of the teeth gap portions 53
 is changed from large to small or vice versa during a cycle in which the
 outer rotor 51 and the inner rotor 52 make one turn. Therefore, the brake
 fluid is sucked from the intake port 60 and is discharged from the
 discharge port 61 to the second conduit A2. Pressures of the wheel
 cylinders can be increased using the discharged brake fluid.
 In this way, the rotary pump 10 can carry out a basic pumping operation in
 which the brake fluid is sucked from the intake port 60 and is discharged
 from the discharge port 61 by rotation of the outer and inner rotors 51
 and 52. During the pumping operation, the outer circumference of the outer
 rotor 51 on a side of the intake port 60 is at intake pressure by brake
 fluid to be sucked through the communicating path 73a and the outer
 circumference of the outer rotor 51 on a side of the discharge port 61 is
 at discharge pressure by brake fluid to be discharged through the
 communicating paths 73b and 73c. Therefore, at the outer circumference of
 the outer rotor 51, the pressure difference exists between the low
 pressure portion communicating to the intake port 60 and the high pressure
 portion communicating to the discharge port 61. Further, at the clearance
 between the axial end surfaces of the outer and inner rotors 51 and 52 and
 the first and second side plates 71 and 72, there exist both high and low
 pressure portions caused by the intake port 60 at low pressure, the
 clearance at low pressure between the drive shaft 54 and the inner rotor
 52, and the discharge port 61 at high pressure.
 However, the brake fluid leakage from the high pressure portion on the side
 of the discharge port 61 to the low pressure portion on the side of the
 intake port 60 at the outer circumference of the outer rotor 51 is
 prevented by the lateral sealing members 80 and 81 formed respectively
 between the communicating path 73a and 73b and between the communicating
 paths 73a and 73c. Further, the transverse sealing members 100 and 101 may
 seal the brake fluid leakage from the high pressure portion to the low
 pressure portion at the clearance between the axial end surfaces of the
 inner and outer rotors 52 and 51 and the first and second side plates 71
 and 72. Furthermore, as the transverse sealing member 100, 101 passes
 through the lateral sealing member 80, 81, there is no gap between the
 transverse sealing member 100, 101 and the lateral sealing members 80, 81
 so that the brake fluid leakage from this gap may be restrained.
 The lateral sealing members 80 and 81 are so operative that the outer
 circumference of the outer rotor 51 on the side of the intake port 60 may
 be exposed to low pressure which is same to the pressure of the teeth gap
 portions 53 communicating with the intake port 60 and the outer
 circumference of the outer rotor 51 on the side of the discharge port 61
 may be exposed to high pressure which is same to the pressure of the teeth
 gap portions 53 communicating with the discharge port 61. As a result,
 pressures at the outer and inner circumferences of the outer rotor 51 are
 balanced so that the pump operation may become stable.
 As mentioned above, both of the lateral sealing members 80 and 81 are
 positioned on the side of the intake port 60 with respect to the center
 line Z, the first and second closed regions 53a and 53b are surrounded by
 the discharge high pressure at the outer circumference of the outer rotor
 51.
 Therefore, as the outer rotor 51 is pressed from both upper and lower sides
 in the drawing and, further, the inner rotor 52 is pushed toward the outer
 rotor 51 on the side of the first closed region 53a so that the teeth top
 clearance between the inner teeth portion 51a of the outer rotor 51 and
 the outer teeth portion 52a of the inner rotor 52 may be diminished, thus
 preventing the brake fluid leakage from the teeth top clearance between
 the inner teeth portion 51a of the outer rotor 51 and the outer teeth
 portion 52a of the inner rotor 52 at the firs t closed region 53a.
 A second embodiment of the present invention is described with reference to
 FIG. 3. FIG. 3 shows an enlarged cross sectional view of a transverse
 sealing member 100 according to the second embodiment as a modification of
 that of the first embodiment. With respect to the structure of the
 transverse sealing member 101 similar to that of the transverse sealing
 member 100, the explanation is omitted.
 The transverse sealing member 100 of the second embodiment is composed of
 an elastic element such as an o-ring 100a smaller than that of the first
 embodiment (refer to FIG. 2B), the resin element 100b and a resin element
 100c disposed at a side of the o-ring 100a.
 The area of the resin element 100b against which the o-ring 100a is pressed
 is restricted. Therefore, the region where the resin element 100b pushes
 the inner and outer rotors 52 and 51 is narrowed so that the contact
 resistance of the transverse sealing member 100 and, thus, the mechanical
 loss thereof may be limited.
 The clearance D1 between the resin elements 100b and 100c is smaller than
 the clearance D2 between the first side plate 71 and the outer or inner
 rotor 51 or 52. When the outer or inner rotor 51 or 52 is pressed to shift
 in an axial direction, the elastic element 100a can not prevent the shift
 because the elastic element 100a itself compresses so that the outer or
 inner rotor 51 or 52 may be in direct contact with the first side plate
 71, thus causing a bigger contact resistance.
 However, according to the second embodiment, the resin element 100b can not
 move beyond the length of the clearance D1 so that the outer or inner
 rotor 51 or 52 may be never in contact with the first side plate 71. As a
 result, the contact resistance, that is, the mechanical loss can be
 limited.
 According to the embodiment mentioned above, though the resin element 100c
 is separately provided, the resin element 100c may be integrally provided
 with the resin element 100b or with the first side plate 71.
 A third embodiment of the present invention is described with reference to
 FIG. 4. FIG. 4 shows an enlarged cross sectional view of a transverse
 sealing member 100 according to the third embodiment as a modification of
 that of the first embodiment. With respect to the structure of the
 transverse sealing member 101 similar to that of the transverse sealing
 member 100, the explanation is omitted.
 A different point from the first embodiment is that the sealing element
 100b according to the third embodiment has a step portion at an outer
 circumference thereof on a side of the inner and outer rotors 52 and 51.
 The resin element 100b on the side of the high pressure discharge port is
 pressed upward in the drawing by high pressure brake fluid acting on the
 step portion, as shown by an arrow in FIG. 4. The pressing force acting
 upward at the step portion counterbalances the biasing force acting
 downward due to the o-ring 100a. Therefore, at the region where the step
 portion is provided, the resin element 100b do not press the inner and
 outer rotors 52 and 51 so that the contact resistance of the transverse
 sealing members 100 and 101 and, thus, the mechanical loss thereof may be
 limited.
 A fourth embodiment of the present invention is described with reference to
 FIGS. 5A and 5B. FIG. 5A shows an enlarged cross sectional view of a
 transverse sealing member 100 according to the fourth embodiment as a
 modification of that of the second embodiment. The transverse sealing
 member 100 is provided with a step portion having the shape as explained
 below in detail. FIG. 5B shows a schematic view for explaining the feature
 of the resin element 100b. With respect to the structure of the transverse
 sealing member 101 similar to that of the transverse sealing member 100,
 the explanation is omitted.
 As shown in FIG. 5B, the step portion of the resin element 100b is shaped
 in a manner that, on a surface of the resin element 100b in contact with
 the outer and inner rotors 51 and 52, a length S1 of the region where the
 O-ring 100a presses is equal to a length S2 of the region where the o-ring
 100a does not press.
 The function of the transverse sealing member 100 as mentioned above is
 described with reference to FIG. 5B. The o-ring 100a presses the resin
 element 100b downward in the drawing. As the pressing force of the o-ring
 100a at the region where the step portion is provided counterbalances the
 brake fluid high pressure as mentioned before, the pressing force of the
 o-ring 100a not to be counterbalanced in this way is distributed as shown
 at an upper side in the drawing as a rectangular shaped slanting line
 portion.
 On the other hand, the pressing force acting on the surface of the resin
 element 100b in contact with the outer and inner rotors 52 and 51 is
 distributed as shown at a lower side in the drawing as a triangular shaped
 slanting portion. As one side (right side in the drawing) of the
 contacting surface of the resin element 100b corresponds to the side of
 the high pressure discharge port 61 and the other side (left side in the
 drawing) thereof to the side of the low pressure intake port 60, the
 pressing force acting on the contacting surface of the resin element 100b
 is the largest on the most right side and becomes smaller gradually
 towards the left side. The resin element 100b is pressed upward in the
 drawing by the brake fluid pressure having the pressing force distribution
 mentioned above.
 As the length S1 is equal to the length S2 as mentioned above, the area of
 the rectangular shaped slanting line portion coincides with the triangular
 shaped slanting line portion. Therefore, all of the pressing force acting
 downward by the O-ring 100a counterbalance the pressing force acting
 upward by the brake fluid pressure so that the contact resistance and,
 thus, the mechanical loss of the transverse sealing member 100 may be
 extremely limited.
 Though the length S1 is equal to the length S2 in the fourth embodiment,
 the contacting force of the transverse sealing member 100 may be adjusted
 by changing the ratio of the length S1 to the length S2.
 A fifth embodiment of the present invention is described with reference to
 FIGS. 6A and 6B. FIG. 6A shows a sectional view of a rotary pump 10
 according to the fifth embodiment. FIG. 6B shows a sectional view taken
 along a line VIB--VIB of FIG. 6A. In FIG. 6A, the transverse sealing
 members 100 and 101 are shown as a dot-dash line and the grooved portions
 71b and 72b as a dot line.
 Though each of the resin elements 100b and 100b of the transverse sealing
 members 100 and 101 according to the first embodiment is shaped
 substantially as a ring with nearly uniform width length, each shape of
 the resin elements 100b and 101b according to the fifth embodiment is not
 the ring with uniform width length but a ring with partly variable width
 length and partly provided with a step portion having advantages as
 described in the third and fourth embodiments.
 The width of the resin element 100b, 100b is partly wider and the resin
 element 100b, 100b is partly provided with a step portion which hangs over
 all of the teeth gap portions 53 communicating with the discharge port 61,
 as shown by a dot-dash line in FIG. 6A.
 As illustrated in FIG. 6B, the resin element 100b, 100b has the step
 portion on outer circumference surface thereof facing the outer and inner
 rotors 51 and 52 only on a side of the discharge port 61 so that only
 limited portions of the resin element 100b, 101b necessary for sealing may
 be in contact with the outer and inner rotors 51 and 52. Portions where
 the resin element 100b, 101b is in contact with the outer and inner rotors
 51 and 52 and the center plate 73 are shown by dot-dash slanting lines in
 FIG. 6A.
 According to the fifth embodiment, the ring shape of the resin element
 100b, 101b corresponds at the inside thereof to, but do not correspond at
 the outside thereof to a ring shape of the grooved portion 71b, 72b.
 Therefore, a gap is constituted between the outer wall of the grooved
 portion 71b, 72b and the outer circumference of the resin element 100b,
 101b by housing the resin element 100b, 100b into the grooved portion 71b,
 72b. Further, there exists a gap between the teeth gap portions 53 and the
 step portion of the resin element 100b, 101b hanging over the teeth
 portions communicating with the discharge port 61. These gaps constitute
 the discharge port 61.
 The ring shaped resin element 100b, 101b is in contact with the inner rotor
 52 between the drive shaft 54 and the teeth gap portions 53 on the side of
 the discharge port 61, then, in contact with the inner and outer rotors 52
 and 51 at the first and second closed regions 53a and 53b, then in contact
 with the lateral sealing members 80 and 81 and, finally, in contact with
 the center plate 73 outside the outer circumference of the outer rotor 51
 on a side of the intake port 60.
 As both of the drive shaft 54 and teeth gap portions 53 on the side of the
 intake port 60 are inside the inner circumference of the ring shaped resin
 element 100b, 101b, the brake fluid leakage from the high pressure side of
 the discharge port 61 to the low pressure side of the clearance between
 the drive shaft 54 and the inner rotor 52 and to the low pressure side of
 the intake port 60 may be prevented.
 Further, the lateral sealing members 80 and 81 serve to separate the high
 pressure side of the discharge port 61 and the low pressure side of the
 intake port 60 at the outer circumference of the outer rotor 51.
 Each outer wall of the grooved portions 71b and 72b crosses at two points
 the outer circumference of the outer rotor 51 on the side of the discharge
 port 61 and each inner wall thereof crosses at two points the outer
 circumference of the outer rotor 51 on a side of the intake port 60.
 Further, the respective grooved portions 71b and 72b have recess portions
 on a side of the discharge port 61, which communicate to the outer
 circumference of the outer rotor 51. Therefore, the high pressure
 discharge port 61 communicates with the teeth gap portions 53 and the
 outer circumference of the outer rotor 51 on the side of the discharge
 port 61. On the other hand, the low pressure intake port 60 communicates
 with the teeth gap portions 53 and the outer circumference of the outer
 rotor 51 on the side of the intake port 60.
 As mentioned above, the resin element 100b, 101b is in minimum contact with
 the outer and inner rotors 51 and 52 to the extent that only necessary
 portions are sealed.
 Further, the inner and outer rotors 52 and 51 are so assembled that brake
 fluid in the teeth gap portion within the first closed region 53a can be
 compressed and the teeth gap portion within the first closed region is
 sealed by the resign element 100b, 101b. On the other hand, the outer
 rotor 51 is pressed from both upper and lower sides in the drawing and,
 further, the inner rotor 52 is pushed toward the outer rotor 51 on the
 side of the first closed region 53a so that the teeth top clearance
 between the inner teeth portion 51a of the outer rotor 51 and the outer
 teeth portion 52a of the inner rotor 52 may be diminished. This pressing
 or pushing load, if it is too strong, is likely to cause an unusual
 frictional wear of the inner and outer teeth portions 51a and 52a.
 However, the brake fluid in the teeth gap portion within the first closed
 region is compressed so that a pressure in a direction of expanding the
 teeth top clearance between the inner and outer teeth portions 51a and 52a
 is operative. Therefore, the load mentioned above is partly cancelled by
 the pressure so that the unusual frictional wear may be prevented.
 A sixth embodiment of the present invention is described with reference to
 FIGS. 7A, 7B and 8. FIG. 7A shows a sectional view of a rotary pump 10
 according to the sixth embodiment. FIG. 6B shows a sectional view taken
 along a line VIIB--VIIB of FIG. 7A. FIG. 8 shows a plan view of the resin
 element 100b, 101b. As shown in FIG. 7B, the first and second side plates
 71 and 72 are provided with the grooved portions 71b and 72b,
 respectively. The grooved portion 71b, 72b is shaped as a ring surrounding
 the outside of the drive shaft 54 and having partly wider width portions
 as shown by a two dots-dash line in FIG. 7A. The center of the grooved
 portion 71b, 72b is eccentric to the center axis of the drive shaft 54
 toward the intake port 60 (left side in the drawing). The grooved portion
 71b, 72b passes through a portion between the discharge port 61 and the
 drive shaft 54, the first and second closed regions 53a and 53b and
 portions where the lateral sealing members 80 and 81 respectively seal the
 outer circumference of the outer rotor 51.
 At respective positions of the intake and discharge ports 60 and 61 that
 cross a hypothetical line connecting the center axis of the drive shaft 54
 and the center line of the grooved portion 71b, 72b, the width of the ring
 shaped grooved portion 71b, 72b is wider so as to overlap both of the
 inner and outer rotors 52 and 51. Further, at positions of the first and
 second closed regions 53a and 53b, the width of the ring shaped grooved
 portion 71b, 72b is also wider.
 Transverse sealing members 100 and 101, in particular resin elements 100b
 and 101b, having the same shapes as those of the grooved portions 71b and
 72b, as schematically shown in FIG. 8, are respectively housed in the
 grooved portions 71b and 72b. The transverse sealing member 100, 101 is
 composed of the resin element 100b, 101b and the elastic element 100a,
 101a, which is similar to the first or second embodiment except that the
 respective resign elements 100b and 101b according to the sixth embodiment
 are provided with wide spread portions 100e, 101e, 100f, 101f, 100g, 101g
 and 100h, 1001h, respectively.
 The wide spread portion 100e, 101e is provided at the discharge port 61 to
 overlap a part of the inner and outer rotors 52 and 53 and the wide spread
 portion 100f, 101f is provided at the intake port 60 to overlap a part of
 the inner and outer rotors 52 and 53. These wide spread portions 100e,
 101e and 100f, 101f are provided for restraining the axially shifting
 movements of the inner and outer rotors 52 and 51 rather than for sealing
 the regions where these wide spread portions 100e, 101e and 100f, 101f are
 placed. Inherently, it is not necessary to seal these regions where the
 discharge and intake ports 61 and 60 are formed.
 On the other hand, the wide spread portions 100g, 101g and 100h, 101h are
 provided to completely block the teeth gap portion within the first and
 second closed regions 53a and 53b so as to seal the brake fluid leakage
 from the teeth gap portions within the first and second closed regions 53a
 and 53b, respectively. Though these wide spread portions 100g, 101g and
 100h, 101h may also serve to restrain mutual axial shifting movement of
 the inner and outer rotors 52 and 51, this is supplemental for the purpose
 of providing the wide spread portions 100g, 101g and 100h, 101h since the
 axially shifting movement of the inner and outer rotors 52 and 51 can be
 substantially prevented by the wide spread portions 100e, 101e and 100f,
 101f.
 As the wide spread portions 100g, 101g and 100h, 101h can focus on sealing
 the teeth gap portions within the first and second closed regions 53a and
 53b, the frictional wear of the wide spread portions 100g, 101g and 100h,
 101h is limited so that the deterioration of the sealing function thereof
 may be slower, compared with the first or second embodiment.
 The wide spread portions 100e, 101e and 100f, 101f are provided with
 openings in order not to completely block any one of the teeth gap
 portions 53 because it is preferable to always communicate any of the
 teeth gap portions 53 variable for sucking or discharging brake fluid with
 the intake or discharge portion 60 or 61.
 Though the width of the wide spread portion 100e, 101e does not reach the
 outer circumference of the outer rotor 51 according to the embodiment
 mentioned above, it is possible to employ the wide spread portion 100e,
 101e having the wider width which reaches the center plate 73. In this
 case, the transverse sealing member 100, 101 is bridged over the center
 plate 73 so that the bending of the transverse sealing member 100, 101 may
 be limited.
 The seventh embodiment of the present invention is described with reference
 to FIG. 9 showing a cross sectional view of a part of a rotary pump. FIG.
 9 shows only a left half of the drawing, compared to the drawing as shown
 in FIG. 6B. Though the transverse sealing members 100 and 101 are in
 contact with the lateral sealing members 80 and 81, respectively,
 according to the embodiments mentioned before, the lateral sealing members
 80 and 81 according to the seventh embodiment are not in contact with the
 transverse sealing members 100 and 101 but placed directly between the
 first and second side plates 71 and 72.
 The brake fluid leakage from the high pressure side to the low pressure
 side through a clearance between the center plate 73 and the outer
 circumference of the outer rotor 51 is prevented by the lateral sealing
 members 80 and 81 arranged within the recessed portions provided at the
 inner circumference surfaces of the center plate 73, which are similar to
 the embodiments mentioned before. It is important, in this case, that the
 thickness (length in an axial direction of the drive shaft 54) of the
 respective lateral sealing members 80 and 81 coincides with a distance
 between the first and second side plates 71 and 72.
 However, due to the manufacturing dimensional deviations or errors,
 clearances through which brake fluid leaks may be formed between each of
 the lateral sealing members 80 and 81 and each of the first and second
 side plates 71 and 72.
 According to the seventh embodiment, the thickness of the resin element
 80b, 81b is larger than the distance between the first and second side
 plates 71 and 72 (thickness of the center plate 73) before the pump is
 assembled, as shown by a dot line in FIG. 9. Then, after assembly, the
 resin element 80, 81 is compressed and deformed by and between the first
 and second side plates 71 and 72. Therefore, there exists no clearances
 between the resin element 80, 81 and the first or second side plate 71 or
 72 so that that the fluid leakage may be prevented.
 An eighth embodiment of the present invention is described with reference
 to FIG. 10. FIG. 10 shows a cross sectional view of a part of a rotary
 pump according to the eighth embodiment. The lateral sealing member 80, 81
 is put between the transverse sealing members 100 and 101, as shown in the
 first to fourth embodiments. Before the pump is assembled, a thickness of
 the resin element 80b, 81b is larger than a thickness of the center plate
 73 so as to be always in contact with the resin elements 100b and 101b.
 Further, a sum of thickness of the resin element 100b, 101b and the
 elastic element 100a, 101a to be piled on the resin element 100b, 101b is
 larger than the depth of the grooved portion 71b, 72b. The resin element
 80b, 81b after assembly is loaded by the resin elements 100b and 101b in a
 manner that the resin element 80b, 81b is put between the resin elements
 100b and 101b. Therefore, the resin element 80b, 81b having the length as
 shown by a dot-line in FIG. 10 is compressed and deformed so that the
 resin element 80b, 81b may be firmly in contact with the resin elements
 100b and 101b.
 According to the eighth embodiment, the brake fluid leakage not only from
 the portion where the resin element 80b, 81b is in contact with the resin
 elements 100b and 101b but also from the clearances between the resin
 elements 100b and 101b and the outer and inner rotors 51 and 52 may be
 effectively diminished.
 A ninth embodiment of the present invention is described with reference to
 FIGS. 11A and 11B. FIG. 11A shows a cross sectional view of a part of a
 rotary pump according to the ninth embodiment. FIG. 11B shows a plan view
 of the elastic element 100a, 101a.
 The elastic element 100a, 101a is an o-ring having projections 100p and
 101p only at the places where the lateral sealing members 80 and 81 are
 arranged. The thickness of the projection 100p, 101p in an axial direction
 of the drive shaft 54 is larger than that of the other portions of the
 o-ring before the resin element 80b, 81b is assembled to the pump, as
 shown in FIGS. 11A and 11B. In more detail, the projection 100p, 101p has
 a cross section as shown by a dot line in the drawing before the
 projection 100p, 101p is loaded. On assembling the pump, the projection
 100p, 101p serves to press and deform more firmly the resin element 80b,
 81b having such a shape as shown by a dot line in the drawing before
 assembly. The ninth embodiment has similar function and effect as
 disclosed in the eighth embodiment.
 A tenth embodiment of the present invention is described with reference to
 FIG. 12. FIG. 12 shows a cross sectional view of a part of a rotary pump
 according to the tenth embodiment.
 A resin element 100q is provided on an opposite side of the resin element
 80b, 81b with respect to the resin element 100b and, also, a resin element
 101q is provided on an opposite side of the resin element 80b, 81b with
 respect to the resin element 101b. The respective resin elements 100q and
 101q are provided separately from the resin elements 100b and 101b only at
 the places where the resin elements 80b and 81b are arranged.
 Each width of the grooved portions 71b and 72b is wider only at the places
 where the resin element 100q and 101q are arranged and the resin element
 100q and 101q are housed in the spaces where the grooved portions 71b and
 72b are wider.
 The resin element 100q, 101q is shaped as shown by a dot line in the
 drawing so that a sum of thickness of the resign element 100q, 101q and
 the resin element 100b, 101b is larger than a depth of the grooved portion
 71a, 72b before the pump is assembled.
 On assembling the pump, both of the resin element 100q, 101q and the resign
 element 80b, 81b are loaded so as to be compressed and deformed so that
 the resin elements 100b and 101b may be firmly in contact with the resign
 element 80b, 81b and also in contact with the center plate 73. The tenth
 embodiment has similar function and effect as disclosed in the eight
 embodiment.
 An eleventh embodiment of the present invention is described with reference
 to FIG. 13. FIG. 13 shows a cross sectional view of a part of a rotary
 pump according to the eleventh embodiment.
 According to the eleventh embodiment, metal springs 100d and 101d are
 provided in place of the resin elements 100q and 101q in the tenth
 embodiment. The resin element 80b, 81b is put between and loaded by the
 resin elements 100b and 101b based on the elastic forces of the metal
 springs 100d and 101d. The eleventh embodiment has similar function and
 effect as disclosed in the eighth embodiment.
 A twelfth embodiment of the present invention is described with reference
 to FIG. 14. FIG. 14 shows a cross sectional view of a part of a rotary
 pump according to the twelfth embodiment.
 According to the twelfth embodiment, the resin element 100b, 101b is
 integrally provided with partly projecting portions in place of the resin
 elements 100q, 101q separately provided from the resin element 100b, 101b
 in the ninth embodiment. The resin element 80b, 81b is put between and
 loaded by the resin elements 100b and 101b in such a manner that a portion
 shown by a dot line in the drawing of the respective partly projecting
 portions is compressed and deformed on assembling the pump. The partly
 projecting portions play the same role as the resin elements 100q, 101q.
 The twelfth embodiment has similar function and effect as disclosed in the
 eighth embodiment.
 A thirteenth embodiment of the present invention is described with
 reference to FIG. 15. FIG. 15 shows a cross sectional view of a part of a
 rotary pump according to the thirteenth embodiment. According to the
 thirteenth embodiment, the resin element 100b, 101b is provided with
 partly projecting elastic portions in place of the partly projecting
 portions to be compressed and deformed in the twelfth embodiment.
 The resin element 80b, 81b is put between and loaded by the resin elements
 100b and 101b in such a manner that the partly projecting elastic portions
 are bent and produce the elastic force on assembling the pump. The
 thirteenth embodiment has similar function and effect as disclosed in the
 eighth embodiment.
 A fourteenth embodiment of the present invention is described with
 reference to FIG. 16. FIG. 16 shows a cross sectional view of a part of a
 rotary pump according to the fourteenth embodiment.
 According to the fourteenth embodiment, the grooved portion 71b, 72b is
 provided with step portions in place of the resin elements 100q and 101q
 in the tenth embodiment. The step portions are respectively provided in a
 depth that is slightly thinner than the thickness of the resin element
 100b, 101b and only at the places where the resin elements 80b and 81b are
 arranged. Therefore, the width of the grooved portion 71b, 72b at each
 position of the step portions is partly narrowed. The resin element 80b,
 81b is put between and loaded by the resin elements 100b and 101b pressed
 partly due to the step portions on assembling the pump. The fourteenth
 embodiment has similar function and effect as disclosed in the eighth
 embodiment.
 A fifteenth embodiment of the present invention is described with reference
 to FIG. 17. FIG. 17 shows a cross sectional view of a part of a rotary
 pump according to the fifteenth embodiment.
 According to the fifteenth embodiment, the grooved portion 71b, 72b is
 provided with step portions described in the fourteenth embodiment and,
 further, the resin element 100b, 101b is provided with notched portions
 for exerting spring force of the resin element 100b, 101b itself. The
 spring force of the resin elements 100b and 101b based on the notched
 portions loads the resin element 80b, 81b put between the resin elements
 100b and 101b. The fifteenth embodiment has similar function and effect as
 disclosed in the eighth embodiment.
 A sixteenth embodiment of the present invention is described with reference
 to FIG. 18. FIG. 18 shows a cross sectional view of a part of a rotary
 pump according to the sixteenth embodiment.
 Though a variety of structures of the transverse sealing member 100, 101
 are described for deforming the resin element 80b, 81b in the axial
 direction of the drive shaft 54 according to the eighth to fifteenth
 embodiments, the resign element 80b, 81b is further provided with a
 notched portion for easing the deformation of the resin element 80, 81b
 itself in the axial direction of the drive shaft 54 according to the
 sixteenth embodiment.
 The resin element 80b, 81b, the thickness of which is larger than that of
 the center plate 73, can be easily deformed by means of the notched
 portions on assembling the pump so that the resin elements 100b and 101b
 may be securely in contact with the resin element 80b, 81b and, also, in
 contact with the center plate 73. The sixteenth embodiment has similar
 function and effect as disclosed in the eighth embodiment.
 A seventeenth embodiment of the present invention is described with
 reference to FIG. 19. FIG. 19 shows a cross sectional view of a part of a
 rotary pump according to the seventeenth embodiment.
 According to the seventeenth embodiment, the elastic element 100a, 101a
 described in the eighth embodiment is fitted to the resin element 100b,
 101b by bonding and the like in advance before the pump is assembled.
 An integrated unit of the elastic element 100a, 101a and the resin element
 100b, 101b can be easily assembled in the grooved portion 71b, 72b. The
 seventeenth embodiment has similar function and effect as disclosed in the
 eighth embodiment.
 A eighteenth embodiment of the present invention is described with
 reference to FIG. 20. FIG. 20 shows a partly enlarged cross sectional view
 of a rotary pump at a vicinity of a lateral sealing member 80 according to
 the eighteenth embodiment. With respect to the lateral sealing member 81
 similar to the lateral sealing member 80, the explanation is omitted.
 The lateral sealing member 80 is composed of an elastic element 80a and a
 resin element 80b. The resin element 80b has a tapered surface at a corner
 on a bottom side of the recessed portion 73d. In more detail, the outer
 circumference of the outer rotor 51 communicating with the intake port 60
 on a left side of the lateral sealing member 80 in the drawing is exposed
 to low pressure and the outer circumference of the outer rotor 51
 communicating with the discharge port 61 on a right side of the lateral
 sealing member 80 in the drawing is exposed to high pressure. The corner
 of the resin element 80b on the high pressure side is cut off to form the
 tapered surface. The elastic element 80a is arranged between the tapered
 surface and the recessed portion 73d.
 The resin element 80b is not only pressed toward the outer circumference of
 the outer rotor 51 but also brought in closed contact with an inner wall
 of the recessed portion 73d on the low pressure side by elastic force of
 the elastic member 80a.
 A nineteenth embodiment of the present invention is described with
 reference to FIG. 21. FIG. 21 shows a partly enlarged cross sectional view
 of a rotary pump at a vicinity of a lateral sealing member 80 according to
 the nineteenth embodiment. With respect to the lateral sealing member 81
 similar to the lateral sealing member 80, the explanation is omitted.
 The lateral sealing member 80 is composed of an elastic element 80a and a
 resin element 80b. The resin member 80b is provided with the tapered
 portion as disclosed in the eighteenth embodiment. The elastic element 80a
 is provided with a flat surface to be in contact with the tapered surface
 of the resin element 80b. The resin element 80b and the elastic element
 80a are integrated by bonding with adhesive and the like the flat surface
 of the elastic element 80a to the tapered surface of the resin element
 80b, which improves the productivity on assembling the lateral sealing
 member 80 to the recessed portion 73d.
 A twentieth embodiment of the present invention is described with reference
 to FIG. 22. FIG. 22 shows a partly enlarged cross sectional view of a
 rotary pump at a vicinity of a lateral sealing member 80 according to the
 twentieth embodiment. With respect to the lateral sealing member 81
 similar to the lateral sealing member 80, the explanation is omitted.
 According to the twentieth embodiment, the tapered surface of the resin
 element 80b is pressed by a tapered surface of the recessed portion 73d in
 place of the elastic element 80a shown in the eighteenth embodiment.
 In more detail, the recessed portion 73d is provided with a tapered portion
 at a place thereof facing the tapered portion of the resin element 80b.
 The tapered portion of the recessed portion 73d presses to deform only a
 part of the tapered portion of the resin element 80b as shown by a
 dot-line in the drawing. The resin element 80b can be pushed in the same
 direction as described in the eighteenth embodiment.
 A twenty-first embodiment of the present invention is described with
 reference to FIG. 23. FIG. 23 shows a cross sectional view of a rotary
 pump according to the twenty-first embodiment, which is a modification of
 the fifth embodiment.
 According to the twenty-first embodiment, the resin element 100b, 101b is
 in contact with the outer and inner rotors 51 and 52 not only around each
 one of the teeth gap portions within the first and second closed regions
 53a and 53b, as shown in the fifth embodiment, but also around each one of
 the adjacent teeth gap portions within the first and second closed regions
 53a and 53b. That is, a dot-dash slanting line portion of the resin
 element 100b, 101b is more expanded, compared with that of the fifth
 embodiment, so that at least two teeth gap portions 53 within the
 respective first and second closed regions 53a and 53b are sealed by the
 resin element 100b, 101b. Further, the outer and inner rotors 52 and 51
 are so arranged that brake fluid in the two teeth gap portions within the
 first and second closed regions is compressed. Therefore, the twenty-first
 embodiment has similar function and effect as disclosed in the fifth
 embodiment.
 The respective designed locations of the maximum and minimum volume teeth
 portions are likely to vary due to the dimensional errors of the outer and
 inner teeth 52a and 51a and other manufacturing errors of the component
 parts of the rotary pump. Therefore, the width of the resin element 100b,
 101b is partly wider to seal at least two teeth gap portions within the
 first and second closed regions 53a and 53b so that the brake fluid
 leakage may be always prevented, even if the contact points where the
 inner and outer teeth portions 51a and 52a are meshed with each other at
 vicinities of the first and second closed regions are deviated due to the
 manufacturing error.
 Though the transverse sealing member 100, 101 is shaped a ring in the
 embodiments mentioned above, the transverse sealing member 100, 101 may
 have the other shape as far as the other shape covers the region from the
 circumference of the outer rotor 51 via the first closed region 53a, a
 portion between the drive shaft 54 and the discharge port 61 and the
 second closed region 53b to the other circumference of the outer rotor 51.
 However, the portions that are not required inherently to be sealed, such
 as teeth gap portions 53 and the outer circumference of the outer rotor 51
 on the intake and discharge port sides which are communicated with the
 intake and discharge ports 60 and 61, respectively, should be in minimum
 contact with the transverse sealing member in order to diminish the
 contact resistance.
 Though the transverse sealing members 100 and 101 are arranged respectively
 on both axial end surface sides of the inner and outer rotors 52 and 51 in
 the embodiment mentioned above, according to a twenty-second embodiment,
 the transverse sealing member 100 may be arranged only on one axial end
 surface side of the inner and outer rotors 52 and 51, that is, only in the
 groove 71b of the first side plate 71, as shown in FIG. 24. The resin
 element 100b biased by the elastic element 100a presses the resin element
 80b of the lateral sealing member 80 so as to be in contact with the one
 axial end surface side of the inner and outer rotors 52 and 51. As a
 result, the inner and outer rotors 52 and 51 are also pushed toward the
 second plate 72 so that a clearance between the inner and outer rotors 52
 and 51 and the second side plate 72 may be diminished and, for example,
 becomes several microns. Therefor, compared with the eight embodiment of
 FIG. 10 where both the transverse sealing members 100 and 101 are
 employed, the similar sealing effect may be secured, while an axial
 shifting between the inner and outer rotors 52 and 51 may be prevented.