Vane pump

Details Vane pump Vane pump

1999-01-08

2001-05-22

Denion, Thomas (Department: 3748)

Rotary expansible chamber devices

With mechanical sealing

Axially movable end wall or end wall portion

C418S259000

Reexamination Certificate

active

06234776

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a vane pump, and in particular to a vane pump which is suitable for supplying oil pressure to a power steering device of a vehicle.
BACKGROUND OF THE INVENTION
A vehicle such as an automobile is provided with a power steering device which uses oil pressure. Conventionally, to supply this oil pressure, a vane pump is used such as is shown in FIG.
13
and FIG.
14
.
The vane pump houses a cam ring
30
, a rotor
31
and vanes
32
which form a pump cartridge
3
in the inner circumference of a body
107
. The cam ring
30
and rotor
31
are disposed between a cover
106
tightened to the body
107
and a side plate
108
fixed to the inner circumference of the body
107
.
The rotor
31
is joined to a drive shaft
50
′ which passes through the body
107
. A pulley is joined to a base end
50
′B of the drive shaft
50
′, and the pulley is connected with an engine. The drive shaft
50
′ drives the rotor
31
and vanes
32
. The drive shaft
50
′ is supported by a bearing
120
provided in the body
107
and a bearing
121
provided in the cover
106
. A tip end
50
′A on the bearing
121
side of the drive shaft
50
′ is housed inside the cover
106
without penetrating the cover
106
.
A ring groove
52
is formed at a predetermined position on the outer circumference of the drive shaft
50
′, and a cir clip
33
engages with the ring groove
52
. The relative displacement of the rotor
31
and drive shaft
50
′ in the axial direction is thereby regulated, and the rotor
31
is joined to the drive shaft
50
′.
When a force acts on the drive shaft
50
′ in such a direction as to push it away from the body
107
, the cir clip
33
comes in contact with the rotor
31
which slides on the side plate
108
, and the displacement of the drive shaft
50
′ in the axial direction is thereby regulated.
A high pressure chamber
101
formed between the inner circumference of the body
107
and the side plate
108
, a passage
111
connecting the high pressure chamber
101
and a flowrate control valve
4
, an intake connector
105
connecting with the outside of the body
107
, and a low pressure passage
109
for recirculating excess hydraulic fluid in the flowrate control valve
4
to the pump cartridge
3
, are provided inside the body
107
.
Hydraulic fluid is supplied under pressure from the pump cartridge
3
via a connecting hole in the side plate
108
, and the required amount of hydraulic fluid is supplied to the power steering device via the passage
111
and flowrate control valve
4
.
Surplus flowrate from the flowrate control valve
4
and hydraulic fluid from the intake connector
105
flow into the cover
106
via the low pressure passage
109
. The hydraulic fluid is sent to an intake area of the pump cartridge
3
via branch passages
102
,
102
formed in the cover
106
. As the cover
106
comprises the branch passages
102
,
102
, it is formed by demolding using a core. A thick part
106
A of predetermined thickness is formed between the branch passages
102
and a contact surface of the cover
106
with the rotor
31
and vanes
32
, and strength is thereby ensured.
Hydraulic fluid which has leaked from the end face of the cam ring
30
, and from a gap between the rotor
31
and the side plate
108
flows back to the low pressure passage
109
from the outer circumference of the bearing
120
via a drain passage
112
inclined at a predetermined angle to the drive shaft
50
′.
However, in the aforesaid prior art, the drive shaft
50
′ is supported by the bearing
120
in the body
107
and the bearing
121
in the cover
106
. Therefore, when the vane pump is assembled, an assembly step must be provided to press the bearing
121
into the cover
106
. The contact surfaces between the cover
106
and the body
107
also must be finished with a predetermined surface precision in order to ensure orthogonality of the cover
106
and drive shaft
50
′ and concentricity of the bearing
121
and drive shaft
50
′. Therefore, the number of machining steps increases, machining time increases, and production costs rise.
The displacement of the drive shaft
50
′ to the right-hand side of
FIG. 13
is restricted by the cir clip
33
, and when it displaces to the left-hand side, the end
50
′A of the drive shaft
50
′ comes in contact with the inner circumference of the cover
106
. Therefore, the depth of the hole into which the bearing
121
is inserted requires to be strictly controlled. As machining is necessary after casting the cover
106
, the number of machining steps and machining time increase, and production costs increase.
As shown in
FIG. 14
, the positional relationship of the cam ring
30
and side plate
108
is determined by a pair of dowel pins
42
,
42
which pass through the cam ring
30
and side plate
108
. The dowel pins
42
are pressed into positioning holes, not illustrated, formed on the surface of the cover
106
on which the rotor
31
and vanes
32
slide. Therefore, the number of machining steps and machining time increase in order to ensure machining precision of this hole.
The vane pump having the aforesaid construction is assembled by assembling each component sequentially to the body
107
or cover
106
, so the number of assembly steps increases. Further, automation of assembly steps is difficult, and productivity cannot be improved.
This invention, which was conceived in view of the aforesaid problems, largely reduces the number of steps used in assembling the vane pump by reducing the steps for machining the cover, and thereby improves productivity. It is a further object of the invention to provide a vane pump whereof the assembly can be automated.
DISCLOSURE OF THE INVENTION
This invention provides a vane pump comprising:
a cam ring comprising a rotor joined to a drive shaft and vanes provided in the rotor such that they are free to move in or out,
a body supporting the drive shaft and housing the cam ring,
a side plate on which are symmetrically provided first low pressure ports corresponding to an intake area of the cam ring and a high pressure port corresponding to a discharge area and connected to a high pressure chamber in the body,
an intake chamber formed between an inner circumference of the body and an upper outer circumference of the cam ring connecting with a low pressure passage for leading hydraulic fluid from the outside,
a branch passage formed between the inner circumference of the body and the upper outer circumference of the cam ring connecting the first low pressure ports of the side plate with the intake chamber, and
a cover comprising an end face joined to an open end face of the body which comes in contact with one end face of the cam ring, wherein second low pressure ports are symmetrically arranged as depressions at positions corresponding to the intake area of the cam ring, and a low pressure distributing groove provided as a depression connected to the intake chamber which splits into two along the upper outer circumference of the cam ring towards the second low pressure ports, and
a pin implanted in the side plate whereof a tip extends by a predetermined amount from the open end face of the body towards the cover, wherein
a throughhole is formed in the cam ring through which the pin passes,
a concave part of predetermined depth is formed in the cover which engages with the tip of the pin, and
an escape hole of predetermined depth for housing a tip end of the drive shaft is formed in the end face of the cover at a position corresponding to the drive shaft.
When the rotor housed inside the cam ring is driven, on one end face of the cam ring, hydraulic fluid in the intake chamber connected to the low pressure passage is aspirated from the second low pressure port via low pressure distributing branch grooves in the cover end face, while on the other end face, it is aspirated to the intake area of the cam ring from between the first low pressure port of the

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