JPH0337384A - Variable capacity type rotary pump - Google Patents

Abstract

PURPOSE:To suppress the variation of the discharge flow rate by the action force of a cam ring by specifying the arrangement position of a cam and the cam profile, in the constitution in which the discharge capacity is controlled by varying the eccentricity quantity of the cam ring for a rotor, by the revolution of the cam. CONSTITUTION:A cam ring 55 which is shiftable, having a pin 56 as fulcrum, onto the outer periphery of a rotor 7 which is rotatable, having a pintle valve 6 as axis, and has a plurality of plungers 10a - 10d which can advance and retreat in the radial direction. The projections 57a and 57b are installed at the lower edge of the cam ring 55, and cam followers 59a and 59b which contact the outer periphery of a cam 62 are axially supported onto the respective projections 57a and 57b. In this case, the cam 62 is arranged so that the revolution center 60 is set on the straight line passing through the contact parts of the cam followers 59a and 59b, and the straight line is set so as to cross at right angles with the line connecting the center of the cam ring 55 and the revolution center 60 in the case when the eccentricity quantity becomes max. and so that the sum of the distance of two contact parts from the revolution center 60 is always constant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable displacement rotary pump that controls discharge displacement by changing the amount of eccentricity of a cam ring with respect to a rotor.

[Conventional technology]

Conventionally, as a variable displacement rotary pump, for example, JP-A-58-
A system disclosed in Japanese Patent No. 18582 is known, in which, as shown in FIG. 9, for example, four cylinders are provided, and the upper part of a cam ring 9° is pivotably supported.
This mechanism controls the eccentricity FJ(e) of the cam ring 90 by applying a spring force by a spring 94 and/or a piston force by a piston 96 to the lower protrusion 92 in the same direction as the swinging direction.

[Problem to be solved by the invention]

However, in this conventional device, a cam ring acting force F as shown in FIG. 10 is generated, and this cam ring acting force F causes the spring 94 and/or piston 96 to fluctuate, and as a result, the eccentricity e of the cam ring increases. Because it fluctuates,
There was a problem in that the discharge flow rate changed.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a variable displacement rotary pump whose discharge flow rate is less likely to fluctuate even when a cam ring action force is generated.

[Means to solve the problem]

In order to achieve the above object, in the present invention, a pump action is achieved by rotating a rotor that is provided eccentrically from a cam ring by a predetermined eccentric amount by a shaft that rotates in response to external power, and the eccentric amount is changed. A variable displacement rotary pump that controls discharge capacity, comprising: a fulcrum portion on which the cam ring is rotatably supported; two contact portions provided on the cam ring and facing each other with a predetermined interval; is provided in contact between the two abutting parts, the center of rotation thereof is on a straight line with the part in contact with the two abutting parts, and the center of rotation is in contact with the two abutting parts. A straight line connecting the abutted portion is perpendicular to a line connecting the center of the cam ring and the rotation center when the eccentricity is maximum, and
The cam is eccentric so that the sum of distances from the rotation center to the portions contacting the two contact portions is always constant.

[Effect]

In the present invention configured as described above, when the eccentric cam rotates, the two contact portions that are in contact with the cam change their positions relative to the rotation center of the eccentric cam while being in contact with each other. The sum of the distances between the contact points is always constant, and the line connecting the center of rotation of the cam and the contact parts of the two contact parts is a straight line, and this straight line is the line when the eccentricity of the cam ring is maximum. Since it is perpendicular to the line connecting the center of the cam ring and the center of rotation of the cam, no rotational torque is generated on the cam even if a cam ring action force is generated. In response to the rotation of the cam, the cam ring rotates about the fulcrum, and the amount of eccentricity between the center of the cam ring and the center of rotation of the rotor changes, and the discharge capacity changes.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a radial plunger type pump according to this embodiment. FIG. 2 is a sectional view taken along the line AA in FIG. 1.

A front housing 1 is fixed to a rear housing 2 via an O-ring 3 with a plurality of bolts 4, and forms the outside of the pump. A shaft 5 rotates by receiving rotational force from an external power source such as an engine via a pulley or the like, and is supported by a bearing 5a. bearing 5
a is fixed to the rear housing 2 by a circlip 5b. Reference numeral 6 is a bottle pulp, which is fixed to the front housing 1 via a gasket 1a with a bolt (not shown).

Reference numeral 7 denotes a rotor, and a cylindrical bushing 8 is press-fitted into an inner bearing hole of the rotor, and is rotatably mounted around the bottle valve 6 as an axis. The rotor 7 rotates by receiving force from the shaft 5 via a coupling plate 12 joined to the shaft 5 via a key 12a. As shown in FIG. 2, the rotor is provided with cylinder holes 9a, 9b, 9c, and 9d radially around the bottle valve 6, with plunge holes 10a, 10b, and 10c, respectively.

10d is slidably incorporated. plunger lo
The heads of a, 10b, 10c, and 10d are hemispherical, and the shoes 14a, 14b have hemispherical indentations.
14c and 14d, and both are pressed against the outer bearing 15 by compression springs 13a, 13b, 13c, and 13d.

Further, the shoes 14a, 14b, 14c, and 14d have protrusions 14a-■ and 14b-■, 14cm-2 (not shown) for lateral positioning of the rotor 7 and the bearing 15, corresponding to each plunger.

14d-■ is provided. 55 is a cam ring with bearing 15 press-fitted inside, and is attached to the front housing l.
It can be moved using a bin 56 as a fulcrum attached to the fulcrum.

Cam followers 59a and 59b as abutting portions are rotatably attached to two protrusions 57a and 57b at the lower end of the cam ring 55 via pins 58a and 58b.

The cam followers 59a and 59b as the contact portions are connected to a cam 62 fixed to a camshaft 60 via a key 61.
It is in contact with the outer periphery of the cam 62 with the cam 62 in between. The camshaft 60 is coaxially connected to a drive shaft 64a of the step motor 4 fixed to the front housing 1 via an adapter 63, and is connected to the front housing l via a bearing 60a and the front housing l via a bearing 60b. It is rotatably attached to a hair ring holder 65 fixed to l with a bolt (not shown). In addition, a shaft 66a of a rotation angle sensor 66 fixed to the rear housing 2 and a coupling 6 are connected to the camshaft 6° (th end).
They are coaxially joined via 7.

In Figures 3 to 6, B-B, CC, and D-D in Figure 1 are shown.
, shows a cross-sectional view taken along line E-E.

The bottle valve 6 has discharge grooves 16a, 16b, 16c, and 16d as shown in FIGS. 3 to 6.

Suction grooves 19a, 19b, 19c, 19d, discharge passages 18a, 18b, 18c, 18d, suction passage 20, and communication holes 17a, 17b, 17c, 17d are provided. The suction grooves 19a, 19b, 19c, 19d all communicate with the suction passage 2o, and the discharge grooves 16a, 16b, 1
6c and 16d are communication holes 17a, 17b, and 17c, respectively.
Through 17d, discharge passages 18a, 18b, 18c
, 18d. The suction passage 20 communicates with a suction port 22 provided in the front housing 1, and the discharge passages 18a, 18b, 18c, and 18d communicate with a discharge port 21a provided in the front housing l and discharge ports 21b, 21c, and 21d (not shown), respectively. is connected to.

The bushing 8 has discharge grooves 16a, 16b, 16, respectively.
Boats 24a, 24b, 24c, corresponding to c, 16d,
24d, each cylinder 9a, 9b is provided in the rotor.
, 9c, 9d and it (rebo) 24a, 24b, 24c
, 24d, and 25b (not shown).

25c and 25d are provided.

A set bolt 71 is attached to the lower surface of the front housing 1 via a holder 70 near the cam 62 so that the position of the tip 71a can be adjusted. On the other hand, the centers of the camshaft 60 and the cam followers 58a to 58b are arranged in a straight line, and as the cam 62 rotates, the R shown in FIG. 1 has the profile shown in FIG. Via 59a and 59b, the cam ring 55 can move around the pin 56 according to the cam profile. Note that the state shown in FIG. 2 is the same as the cam angle 9 in FIG.
This is a state of 0°, which indicates a state where the cam ring eccentricity e is at its maximum. A stopper 72 is connected to the side surface of the cam 62, and the tip 71 of the set bolt 71 is connected at the cam angle of O°.
It comes into contact with a and cannot rotate any further.

Moreover, between the adapter 63 and the front housing 1,
The coiled spring 63a is attached so as to exert a force on the camshaft 60 in the direction that the cam angle becomes 0° (counterclockwise in FIG. 2).
is the assembly.

An oil seal 80 is provided between the shaft 5 and the rear housing 2, and an oil seal 80 is provided between the camshaft 60 and the front housing l.
An oil seal 81 is disposed between the camshaft 60 and the bearing holder 65, and an oil seal 82 is disposed between the camshaft 60 and the bearing holder 65 to prevent fluid from leaking from inside the pump.

Next, the operation of this embodiment having the above configuration will be explained.

In FIG. 1, when the shaft 5 rotates in response to external power (not shown), the rotor 7, which is connected to the coupling plate 12 with bolts, rotates about the bottle valve 6 fixed to the front housing l. At this time, the bushing 8, which is a sliding member, is incorporated into the rotor tough on the surface that slides on the bottle valve 6, so that it can rotate smoothly. A plunger 10d is slidably incorporated into the rotor as shown in FIG. 2 as the rotor turns.

10b, 10c, 10d and plunge-t-10a.

10b, a shoe 14a that is movably assembled along the inner ring of a bearing 15 that is in contact with the head of the IOC and lod and is incorporated into the cam ring 55;

14b, 14c, and 14d rotate. At this time, the rotor 7 rotates concentrically with the bottle valve 6, but as shown in FIG. 2, the center of the cam ring 55 and the center of rotation of the rotor 7 are eccentric by an arbitrary value e, so each plunger 10a to 10d are cylinders of the rotor so that as the rotor 7 rotates, the rotor is closest to the center of the rotor when it reaches the position of the plunger 10b in FIG. The cylinder reciprocates within the cylinder with a stroke amount of 2C, and fuel is sucked into and discharged into each cylinder hole 9a, 9b, 9c, and 9d. Suction into each cylinder hole 9a, 9b, 9c, 9d is carried out through a suction passage 20.
Suction grooves 19a, 19 shown in FIGS. 3 to 6, respectively.
b, 19c, 19d, bo) 24a, 24b, 24c,
24d, and cylinder communication holes 25a, 25b, 25c
, 25d, and conversely, the discharge is carried out through the cylinder communication passages 25a, 25b, 25c, 25d and the port 24, respectively.
a, 24b, 24c, 24d, discharge groove 16a.

16b, 16c, 16d, communication holes 17a, 17b.

17c, 17d, discharge passages 18a, 18b, 18c, 1
8d.

When the step motor 64 rotates in response to a signal from a control device (not shown), the camshaft 60 connected via the adapter 63 rotates, and when the cam 62 connected to the camshaft 60 rotates, the cam 62 rotates as shown in FIG. Since the cam surface has a cam surface according to the profile shown in FIG.
b rotates smoothly around the pins 58a and 58b, moves the cam ring 55 around the pin 56 fixed to the front housing as a fulcrum, and adjusts the eccentricity 1e between the cam ring 55 and the rotor 7 to a target value. Can be controlled.

Cam ring 55 and cam follower 59a in this embodiment
, 59b, cam 62, and stopper 72 are shown in FIG.
From the protrusions 57a and 57b on the lower end of the cam ring, the bottle 58a,
Cam follower 59a via 58b, cam 62 from 59b
and acts on the camshaft 60, the rotation center of the cam 620 and the cam follower 59a.

The center of 59b is on a straight line, and this straight line is provided so as to be perpendicular to the line connecting the center of the cam ring 55 and the rotation center of the cam 62 when the cam ring 55 is at its maximum eccentricity (when e is at its maximum). , the cam ring acting force F is the cam 62
and a bearing 60a that rotatably holds the camshaft 60 without acting in the direction in which the camshaft 60 rotates.

(It is applied to 30b and does not affect the rotational torque of the step motor 64 connected to the camshaft 60,
Also, since R, +R, = constant in the profile of the cam 62, the two cam followers 59a, 59
The diameter of the cam 62 at the portion sandwiched by b is always constant, and there is no play between it and the cam followers 59a and 59b.

Therefore, in the radial plunger pump of this embodiment, the eccentricity e between the center of the cam ring 55 and the center of the rotor does not vary due to the cam ring acting force, and a stable discharge amount can be maintained.

Moreover, between the adapter 63 and the front housing 1,
Since the spring 63a is set so that force is generated in the direction that reduces the eccentricity 1e, when the vehicle equipped with this pump stops working and the signal to the step motor 64 stops, the camshaft 60 will change the eccentricity. 51e rotates in the direction of decreasing, and when the eccentricity le reaches the position where e=o, the stopper 72 attached to the cam 62
Since it comes into contact with the tip 71a of the set bolt 71 fixed to the front housing l via the holder 70 and is fixed, the next time the step motor 64 starts operating,
Since the eccentricity e between the cam ring 55 and the rotor 7 always starts from the position e=o, accurate driving of the step motor 64 can be realized.

In the above embodiment, a method was described in which the step motor 64 was used to control the eccentric ile. Is the camshaft 60 a rotating body? 11.

Further, although the present radial plunger pump has been described as an injection pump having separate discharge passages corresponding to the number of plungers, the present invention may also be applied to a radial plunger type flow pump having a common discharge passage.

〔Effect of the invention〕

As explained above, according to the present invention, since the sum of the distances from the rotation center of the cam to the point where the cam and two contact parts contact is always constant, there is a gap between the contact part and the cam. No rattling occurs. Also, the point where the cam contacts the two contact parts is in a straight line with the center of rotation of the cam, and this straight line is the center of the cam ring and the center of rotation of the cam when the eccentricity of the cam ring is at its maximum. Since it is perpendicular to the line connecting the cam ring, the force acting on the cam ring does not generate any force that tries to rotate the cam.

Therefore, it is possible to obtain a variable displacement rotary pump with little variation in discharge flow rate even when a cam ring action force is generated, which is an excellent effect.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
3 is a sectional view taken along the line A-A in the figure, FIG. 3 is a sectional view taken along the line B-B of the main part in FIG. 1, and FIG.
5 is a sectional view taken along line D-D of the main part in FIG. 1, FIG. 6 is a sectional view taken along line E-C of the main part in FIG. FIG. 8 is a perspective view showing the main parts of the above embodiment; FIG. 9 is a diagram showing the profile of the cam;
FIG. 1 and FIG. 1O are diagrams for explaining a conventional variable displacement rotary pump. 5...Shaft, 7...Rotor, 55...Cam ring. 56... Fulcrum part, 59a, 59b... Contact part, 62
···cam.

Claims (1)

[Scope of Claims] A variable displacement device that performs a pumping action by rotating a rotor, which is provided eccentrically from a cam ring by a predetermined amount of eccentricity, by a shaft that rotates in response to external power, and controls the discharge volume by changing the amount of eccentricity. The rotary pump includes: a fulcrum portion on which the cam ring is rotatably supported; two contact portions provided on the cam ring and facing each other with a predetermined interval; The center of rotation is in line with the part that abuts the two abutting parts, and connects the center of rotation and the part that abuts the two abutting parts. The straight line is orthogonal to a line connecting the center of the cam ring and the center of rotation when the eccentricity is maximum, and
A variable displacement rotary pump characterized by comprising: a cam that is eccentric so that the sum of the distances of the portions contacting the two contact portions from the center of rotation is always constant.