JPH09195926A - Radial plunger pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent operating liquid from flowing to the periphery of a driving shaft, so as to improve lubricating performance around a driving shaft supporting part without increasing manufacturing costs, deteriorating durability of components, and enlarging a device, by a structure having the small number of parts and by which large stress is prevented from acting the components. SOLUTION: An eccentric cam 15 is integrally provided on a driving shaft 11, and a plurality of plungers 18 are radially provided on a housing 6. An auxiliary ring 39 is relatively rotatably provided on the outer periphery of the eccentric cam 15, and respective plungers 18 are pressed through the auxiliary ring 39. Bellows 41a, 41b for surrounding the driving shaft 11 and for partitioning the housing 6 into an operating liquid chamber 44 and a lubricating liquid chamber 45 are arranged between the auxiliary ring 39 and the housing 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial plunger pump used for a fuel pressurizing pump of a fuel injection device of an automobile, and more particularly to a radial plunger pump having improved lubrication performance in a housing.

[0002]

2. Description of the Related Art As a radial plunger pump, an eccentric cam having a circular cross section is integrally provided on a drive shaft, and a plurality of plungers are moved forward and backward in a housing at a position facing the outer peripheral surface of the eccentric cam. There is a structure provided freely. In this radial plunger pump, when the eccentric cam rotates with the rotation of the drive shaft, a plurality of plungers facing the eccentric cam are sequentially pushed by the eccentric cam to repeatedly project and retract, and when the plungers project, the suction passage The hydraulic fluid sucked in from is discharged to the discharge passage when the plunger is retracted.

By the way, in recent years, this type of radial plunger pump has come to be used as a fuel pressurizing pump of a fuel injection device of an automobile. However,
When the radial plunger pump is used in such applications, low-viscosity hydraulic fluid such as gasoline leaks into the peripheral area of the drive shaft support from the sliding gap between the plunger and cylinder hole, It is conceivable that the lubrication performance of the bearings and seal parts in the parts will deteriorate.

Therefore, conventionally, as a radial plunger pump capable of coping with this, for example, an actual open flat plate 6-432.
A device as shown in Japanese Patent Publication No. 74 has been devised.

In this radial plunger pump, a caulking material is projectingly provided on the head of each plunger, and a diaphragm is liquid-tightly arranged between the caulking material of each plunger and a peripheral portion of a cylinder hole corresponding to the caulking material. Then, the space around the drive shaft support part separated from the plunger part by each diaphragm is filled with a lubricating liquid of a predetermined viscosity, and the bearing and oil seal around the drive shaft support part is filled with the lubricating liquid separately from the working liquid. I am trying to supply it.

[0006]

However, in the case of the above-mentioned conventional radial plunger pump, since the caulking material and the diaphragm have to be attached to each plunger, the number of parts increases and the structure becomes complicated. There is a problem that the manufacturing cost increases and the device becomes large.

Further, in the above-mentioned conventional radial plunger pump, since the diaphragm is arranged between each plunger and the peripheral portion of the cylinder hole corresponding thereto, the diameter of the diaphragm should be sufficiently large. Therefore, it is conceivable that the stress acting on the diaphragm is increased, which is disadvantageous in terms of durability.

In view of this, the present invention reliably prevents the working fluid from flowing into the peripheral region of the drive shaft support portion with a simple structure in which the number of parts is small and large stress does not act on the components. An object of the present invention is to provide a radial plunger pump that can reliably improve the lubrication performance around the drive shaft support portion without causing problems such as an increase in manufacturing cost, a decrease in durability of components, and an increase in size of the device. It is a thing.

[0009]

As a means for solving the above-mentioned problems, the present invention is such that an eccentric cam having a circular cross section is fixedly mounted on a drive shaft rotatably supported in a housing. Plural plungers are provided in the housing in a position facing the outer peripheral surface of the eccentric cam so as to be able to advance and retreat in the radial direction, and the plural plungers are sequentially pressed by the rotation of the eccentric cam and sucked from the suction passage. In a radial plunger pump that sends hydraulic fluid to a discharge passage, an auxiliary ring is fitted to the outer circumference of the eccentric cam so as to be relatively rotatable, and a drive shaft is surrounded between the auxiliary ring and the housing to create a hydraulic fluid chamber inside the housing. A flexible partition member is provided for partitioning the bearing and the lubricating liquid chamber. Since the auxiliary ring is rotatable relative to the eccentric cam, when the eccentric cam rotates together with the drive shaft, the auxiliary ring revolves around the drive shaft without rotating. By the cooperation of the auxiliary ring and the separating member, the lubricating liquid chamber in the peripheral region of the drive shaft support portion is completely separated from the working liquid chamber.

The partition member is formed of a bellows so that it can flexibly follow the revolution of the auxiliary ring around the drive shaft.

Further, the bellows are improved in durability when formed of a metal material, and can be manufactured at low cost when formed of a rubber material or a resin material.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

In this embodiment, the radial plunger pump 1 according to the present invention is applied to a fuel pressurizing pump of a fuel injection device for an automobile. As shown in FIG. Fuel (working fluid) such as gasoline, which is supplied in a low pressure state via the radial plunger pump 1, is pressurized to a predetermined pressure and supplied to the injector 4, and the fuel is injected by the injector 4 into a cylinder of an engine (not shown). .) And the excess fuel is returned from the injector 4 to the suction passage 5 of the pump 1.

In this radial plunger pump 1, a housing 6 is composed of a substantially cylindrical housing body 7 which also serves as a cylinder block, a front cover 9 and a rear cover 10 which are connected to front and rear end surfaces thereof by bolts 8. The drive shaft 11, which is inserted into the housing 6 from the front cover 9 side, has a rear cover 10 and a front cover 9.
The drive shaft 11 and the front cover 9 are sealed by an oil seal 14 while being supported by bearings 12 and 13, respectively. A circular eccentric cam 15 whose center is offset from the rotation center of the drive shaft 11 by a predetermined amount is integrally provided at a substantially central portion of the drive shaft 11 housed in the housing 6. A cam shaft (not shown) of the engine is coupled to an end portion of the housing 11 that projects from the housing 6.

Further, the housing body 7 is provided with a plurality of radial cylinder holes 17 in a radial direction, and a plunger 18 biased by a spring in the direction of the eccentric cam 15 is movable back and forth in each of the cylinder holes 17. It is housed in. In the figure, 19 is the housing 6 of each cylinder hole 17.
This is a plug for closing the end on the outer peripheral side. As shown in FIGS. 2 and 3, the housing body 7 is provided with a connection port 20 communicating with each cylinder hole 17, and an intake port 21 communicating with each connection port 20.
And a discharge port 22 are provided along the axial direction.
The suction port 21 and the discharge port 22 are paired with each other and are formed on the same straight line, and the connection port 20 is connected to the connecting portion of both ports 21 and 22. A suction check valve 23 and a discharge check valve 24 are provided in both of the ports 21 and 22, respectively, and when the plunger 18 projects suction, the discharge check valve 24 is closed and the suction check valve 23 is opened. At the time of the backward discharging of 18, the suction check valve 23 is closed and the discharge check 24
Is designed to open. That is, when the plunger 18 projects, the hydraulic fluid in the suction port 21 is sucked into the cylinder hole 17 through the connection port 20, and when the plunger 18 retracts from that state, the cylinder hole 1
The hydraulic fluid in 7 is sent out to the discharge port 22 through the same connection port 20. Also, all intake ports 21
Communicates with a suction side annular groove 25 formed on the end surface of the housing body 7 on the front cover 9 side, and similarly, all the discharge ports 22 are formed on the end surface of the housing body 7 on the rear cover 10 side. It communicates with the side annular groove 26. These annular grooves 25, 26 communicate with the suction passage 5 and the discharge passage 27 in the housing 6, respectively.

In the drawings, 28 and 29 are a low pressure regulator and a high pressure regulator incorporated in the rear cover 10, and the low pressure regulator 28 is interposed in the middle of the suction passage 5 to maintain the suction pressure at a set low pressure, and the high pressure regulator. Reference numeral 29 is connected to the return pipe from the injector 4 (in the figure, the return pipe connection port of the high-pressure regulator 29 is shown by reference numeral 30) so that the injection pressure of the injector 4 is maintained at a set high pressure. These regulators 2
8 and 29, when the pressure in the passage exceeds the set pressure,
The low pressure regulator 28 has a schematic configuration in which a part of the hydraulic fluid in the passage is drained, as shown in FIG.
The drain port 31 on the side is connected to the fuel tank 2 through the return pipe connection plug 32, and the drain port 33 on the side of the high-pressure regulator 29 is connected to the suction passage 5.

Here, the shape of the suction passage 5 in the housing 6 will be briefly described. The suction passage 5 extends from the suction pipe connection port 34 formed in the rear cover 10 toward the high pressure regulator 29, and the high pressure regulator 29 has the same structure. The direction is changed via the annular groove 35 in the peripheral region, and the housing body 7
Communicates with the suction-side annular groove 25 on the end surface of the.

On the other hand, an auxiliary ring 39 is relatively rotatably fitted to the outer peripheral surface of the eccentric cam 15 formed on the drive shaft 11 via a metal bearing 38, and the outer periphery of the auxiliary ring 39 is further fitted. A seat cam 40 made of metal having a high hardness and a small friction coefficient is adhered to the surface, and the head of each spring-biased plunger 18 is pressed against the seat cam 40. The drive shaft 11 is provided at both axial ends of the auxiliary ring 39.
One end of each of metal bellows 41a and 41b covering the peripheral region of is welded in a sealed state. Each bellows 41
The other ends of a and 41b are similarly welded to annular mounting rings 42 and 43 in a sealed state, respectively, and these mounting rings 42 and 43 are respectively attached to the inner recesses 9a and 10a of the front cover 9 and the rear cover 10. It is fixed by press fitting. Both the bellows 41a, 41b constitute a flexible partitioning member in the present invention, and a lubricating liquid of a predetermined viscosity is enclosed in the internal space surrounding the drive shaft 11. That is,
Both bellows 41a, 41b are provided inside the housing 6,
Leakage hydraulic fluid (fuel) from the sliding gap of the plunger 18
Is divided into a working fluid chamber 44 filled with the above and a lubricating fluid chamber 45 filled with a lubricating liquid.

In FIG. 6, reference numeral 46 denotes a drain port for returning the hydraulic fluid in the hydraulic fluid chamber 44 to the suction passage 5, and 47
Is a safety valve connected to the discharge side annular groove 26. The drain side of the safety valve 47 is connected to the hydraulic fluid chamber 44, and when the discharge pressure of the discharge passage 27 rises above a set pressure, a portion of the hydraulic fluid of the discharge passage 27 is sucked through the hydraulic fluid chamber 44. It is designed to be returned to the passage 5. In addition, 36 is
A discharge pressure sensor provided between the discharge-side annular groove 26 and the discharge pipe connection port 37.

In the above structure, when the drive shaft 11 rotates with the start of the engine, the eccentric cam 15 provided integrally with the drive shaft 11 rotates, which causes the auxiliary ring 39 to rotate on the bellows 41a and 41b. The drive shaft 11 revolves around the drive shaft 11 while being blocked. Thus the auxiliary ring 39
When the orbit of the seat cam 40 revolves around the auxiliary ring 39,
Pushes up each plunger 18 in sequence, whereby the plunger 18 repeats the forward / backward movement, so that the pump action is continuously performed. At this time, the working fluid (fuel) supplied from the fuel tank 2 to the suction pipe connection port 34 via the supply pump 3 is regulated to a set low pressure by the low pressure regulator 28 in the middle of the suction passage 5, and then the high pressure regulator. 29 through the annular groove 35, the suction-side annular groove 25 of the housing body 7, the suction port 21, the suction check valve 23, and the connection port 20 in order to be sucked into the cylinder hole 17.
Here, after being pressurized by the plunger 18, it sequentially passes from the cylinder hole 17 through the connection port 20, the discharge check valve 24, the discharge port 22, the discharge side annular groove 26, and the discharge passage 27, and then from the discharge pipe connection port 37 to the injector 4. Supplied. Then, the surplus of the hydraulic fluid used in the injector 4 is the return pipe connection port 3 of the high pressure regulator 29.
0, and is returned from the high pressure regulator 29 to the suction passage 5 via the annular groove 35 on the outer periphery thereof.

When the radial plunger pump 1 is continuously operated in this manner, the hydraulic fluid leaks into the housing body 7 through the sliding gap of the plunger 18 and the like. Since the working fluid chamber 44 and the lubricating fluid chamber 45 are separated by the ring 39 and the bellows 41a and 41b in a completely sealed state, the working fluid of low viscosity is kept in the bearings 12, 13 and the oil seal 14 around the drive shaft 11. It doesn't get in. The lubricating liquid chamber 45 is filled with a lubricating liquid having a predetermined viscosity, and the bearing 1
Since the lubricating liquid is always spread over the oil seals 2, 13 and the oil seal 14, the initial performance of the bearings 12, 13 and the oil seal 14 is guaranteed for a long period of time.

Here, this radial plunger pump 1
In the above, the partitioning member for partitioning the hydraulic fluid chamber 44 and the lubricating fluid chamber 45 is composed of bellows 41a and 41b, and
Since the axial length thereof is set to be sufficiently long with respect to the displacement of the auxiliary ring side connection portion due to the revolution of the auxiliary ring 39, the partitioning members (bellows 41a, 41b) are provided with respect to the revolution of the auxiliary ring 39. The whole area will be gently deformed and will flexibly follow. For this reason, a large stress is not locally applied to the bellows 41a and 41b, which are the separating members, and a problem that power loss is increased does not occur. Also,
Since the bellows 41a, 41b are made of metal, they have high durability and can be used for a long time.
There is no fear of deterioration of 41b. The metal bellows 41a and 41b may be integrally formed as shown in FIG. 1 or may be so-called welded bellows in which a plurality of annular metal plates are joined by welding.

The embodiments of the present invention are not limited to those described above. For example, the bellows may be formed of a rubber material or a resin material, or a thin rubber material may be used as the separating member instead of the bellows. It is also possible to adopt a structure in which a resin material is gently curved.

[0024]

As described above, according to the present invention, the auxiliary ring is fitted to the outer periphery of the eccentric cam so as to be relatively rotatable, the drive shaft is surrounded between the auxiliary ring and the housing, and the inside of the housing is filled with the hydraulic fluid chamber. By providing a partitioning member that separates the hydraulic fluid chamber and the lubricating fluid chamber, the simple structure with a small number of parts can reliably prevent the hydraulic fluid from flowing into the peripheral region of the drive shaft support portion, thus reducing the manufacturing cost. It is possible to reliably improve the lubrication performance around the drive shaft support portion without increasing the number of components and increasing the size of the device. Further, in the case of the present invention, the flexible separating member is
Since it is provided between the auxiliary ring fitted to the eccentric cam and the housing, the maximum amount of deflection with respect to the length of the separating member is reduced, and as a result, the stress acting on the separating member is reduced. The durability is improved.

When the separating member is formed of a bellows, the separating member flexibly follows the revolution around the drive shaft of the auxiliary ring, resulting in the stress concentration of the separating member. This can be avoided, and the power loss of the drive shaft can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG. 1;

FIG. 3 is a sectional view taken along the line BB in FIG. 2;

FIG. 4 is a sectional view taken along the line CC of FIG. 1;

FIG. 5 is a sectional view taken along line DD of FIG. 1;

6 is a cross-sectional view taken along the line EE of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Radial plunger pump, 5 ... Suction passage, 6 ... Housing, 11 ... Drive shaft, 15 ... Eccentric cam, 18 ... Plunger, 27 ... Discharge passage, 39 ... Auxiliary ring, 41a, 41b ... Bellows (separating member), 44 ... Working fluid chamber, 45 ... Lubricating fluid chamber.

Claims (4)

[Claims] 1. An eccentric cam having a circular cross section is fixedly mounted on a drive shaft rotatably supported in a housing, and a plurality of plungers are provided in a position facing the outer peripheral surface of the eccentric cam in the housing. In a radial plunger pump that is provided so as to be movable back and forth in the radial direction, and the plurality of plungers are sequentially pressed by the rotation of the eccentric cam and send the working fluid sucked from the suction passage to the discharge passage. An auxiliary ring is fitted so as to be relatively rotatable, and a flexible partition member is provided between the auxiliary ring and the housing to surround the drive shaft and divide the inside of the housing into a working fluid chamber and a lubricating fluid chamber. Radial plunger pump characterized by 2. The radial plunger pump according to claim 1, wherein the partition member is formed of a bellows. 3. The radial plunger pump according to claim 2, wherein the bellows is made of a metal material. 4. The radial plunger pump according to claim 2, wherein the bellows is made of a rubber material or a resin material.