JP2619727B2 - Radial piston pump for low viscosity fuel oil - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial piston pump, particularly to a radial piston pump suitable for high-pressure pumping of low-viscosity fuel oil.

[Conventional technology and its technical problems]

Improvement of combustion efficiency has been demanded as a measure against pollution problems and resource depletion due to exhaust gas from internal combustion engines of vehicles and the like. As a countermeasure, it is said that it is effective to increase the atomization of spray by increasing the pressure in gasoline, and methanol or a similar fuel (hereinafter simply referred to as methanol) is used as a fuel instead of gasoline. Application is being considered. Since this methanol has poor cold startability, it also needs to be atomized by increasing the pressure.

To achieve this, the discharge pressure of the normal fuel pump
Instead of ~4kgf / cm ^2, it is necessary a pump capable of exhibiting a high discharge pressure performance that 70~100kgf / cm ^2, as the one form,
A radial piston pump is conceivable in terms of capacity and efficiency. However, conventional radial piston pumps
As shown in JP-A-64-367, a hydraulic pump, that is, a high-viscosity oil (having a viscosity of 30 cst or more) is generally used as a pumping means. Such a high-viscosity oil has no performance problem, but the fuel oil has a very low viscosity of about 0.5 cst.

When trying to discharge fuel oil of such characteristics at high pressure,
If the pump structure is changed from a rotary type that rotates the cylinder block to a fixed cylinder type where only the piston reciprocates with the cylinder block fixed, the grease sealed in the bearing of the drive shaft may be washed and diluted with low-viscosity oil. The problem of galling and seizure between the cylinder and the barrel and between the eccentric cam and the tip of the piston cannot be solved. For this reason, the conventional radial piston pump cannot smoothly and stably supply the low-viscosity fuel oil under high pressure.

The present invention has been made in order to solve the above-described problems, and an object of the present invention is to use a low-viscosity fuel oil represented by gasoline or methanol without impairing the lubricity of a bearing portion. Another object of the present invention is to provide a practical radial piston pump capable of pumping to a high pressure of 70 kgf / cm ² or more and stably pumping without causing galling or seizure of a piston sliding portion.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a pump having a fixed cylinder and a plurality of pistons radially arranged on the fixed cylinder, wherein these pistons are reciprocated by rotation of an eccentric cam of a pump shaft. Around the cylinder on which the piston is disposed, a housing having a suction port and a cover having a discharge port are respectively integrally connected, and a pump shaft having an eccentric cam is supported by a bearing in the cover and the housing. Between the outer periphery of the eccentric cam and the inner wall of the cylinder and between the outer periphery of the pump shaft and the inner wall of the housing behind the eccentric cam, a series of annular chambers for storing low-viscosity fuel oil via a suction port are formed, and in the axial direction of the annular chamber. Has an oil seal that blocks mixing of low-viscosity fuel oil and bearing grease,
The housing is provided with a radial passage through which the low-viscosity fuel oil is sucked into the suction hole of each piston by using the annular chamber as a part of the flow path.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

1 to 10 show a first embodiment of the radial piston pump according to the present invention. 1 and 2 show the entire structure, and FIGS. 3 to 10 show details of each part.

1 and 2, A is a cylinder and B is a housing, which is in contact with one end face in the axial direction of the cylinder A via a leaf valve D and a gasket E. C is a cover, which is in contact with the other end face in the axial direction of the cylinder A via a leaf valve D 'and a gasket E'.

The cylinder A, the housing B, the cover C, the leaf valves D and D ', and the gasket E' are each provided at the same position with a plurality of pin insertion holes 100 and bolt holes 101 (five in FIG. It is a hole.)
The pin 102 is fitted in the pin insertion hole 100 to perform positioning in the circumferential direction, and is integrated by tightening a bolt hole 101 through a stud bolt 103. F is a pump shaft, which is rotated via a drive pulley G by driving an external engine.

The cylinder A has a cylindrical shape as shown in FIGS. 1, 3 and 4, and has a plurality (five in the embodiment) of cylinder holes 2 penetrating from the inner wall 1 to the outer wall. Radially formed at equal intervals, cap-shaped pistons 3 are respectively slidably fitted in the respective cylinder holes 2, and each of the cap-shaped pistons 3 is supported at one end by a plug 4 screwed and fixed to the cylinder hole 2. The spring 5 is biased in the centripetal direction.

The housing B has a cylindrical shape, and has an inner wall 6 having a diameter matching the inner wall 1 of the cylinder A as shown in FIG.
An enlarged hole 7 is formed from the half part via a step. The cover C is concentric with the cylinder A and the housing B and has a stepped blind hole 8 having a small diameter.

As shown in FIG. 1, the pump shaft F has a small-diameter portion 9a from the tip to the rear, an eccentric cam portion 9b at a position corresponding to the cylinder region, a large-diameter portion 9c concentric with the small-diameter portion 9a, and a step. The small-diameter portion 9a is received by a thrust bearing 10 disposed at the bottom of the stepped blind hole 8 and supported by a radial bearing 11 disposed at the inner periphery of the hole. The portion 9d is supported by a radial bearing 12 arranged in the enlarged hole 7.

The eccentric cam portion 9b and the large diameter portion 9c are smaller in diameter than the inner walls 1 and 6 of the cylinder A and the housing B, and the outer circumferences of the eccentric cam portion 9b and the large diameter portion 9c and the inner walls of the cylinder A and the housing B.
An annular chamber 13 for storing the low-viscosity fuel oil is formed between the first and sixth chambers. The axial direction of the annular chamber 13 corresponds to the stepped blind hole 8.
And oil seal 1 provided at each entrance area of enlarged hole 7
The bearing side is separated by 4, 15
Prevents the grease enclosed in 11, 12 from being diluted with clean low-viscosity fuel oil.

As shown in FIGS. 1 and 3, the eccentric cam portion 9b is integrated with a cam body 90, a metal bush 91 externally rotatably fitted to the cam body 90, and press-fitted into the metal bush 91 by any method such as press fitting. A guide ring 92 of high hardness (although it may of course be a separate body) is provided, and the tip of the curvature of the cap-shaped piston 3 is brought into contact with the guide ring 92.

The metal bush 91 and the guide ring 92 have a large diameter portion 9c at the right end and a retaining ring 93 attached to the cam body 90 at the left end.
The movement is prevented by each. Metal bush 91
In FIG. 2A, a fine spiral oil groove 910 is formed on the inner surface as shown in FIG. 2A, and lubrication between the cam body 90 and the flow of low-viscosity fuel oil by the spiral oil groove 910 is achieved.

As the high hardness guide ring 92, for example, SUJ material, fine ceramics, or the like is used. The cam main body 90 may be formed integrally with the pump shaft F as shown in FIG. 1 and hardened on the surface, or may be formed separately from the pump shaft F as shown by a virtual line in FIG. And a key.

A pressurized chamber 30 having an enlarged diameter is formed in a cylinder hole portion corresponding to the upper end portion of each cap-shaped piston 3, and the right end face of the cylinder corresponding to each pressurized chamber 30 is shown in FIGS. As shown in FIG. 4, a counterbore 31 having a suction side passage hole 33 communicating with the pressurizing chamber 30 is formed, and a discharge side passage opened in the left end surface of the cylinder on the side opposite to the suction side passage hole 33. A hole 34 is drilled.

On the other hand, at the position corresponding to the counterbore 31, the housing B is provided with suction passages 16 which are opened at the left end face as shown in FIGS. 1 and 5, respectively.
16 is bent at the back side and serves as a radial passage 160 for the annular chamber 13.
, The low-viscosity fuel oil is sucked in from here. One suction passage 16 has a filter 17 inside.
A suction port member 17 having a zero is communicated with the low-viscosity fuel oil tank via a conduit (not shown).

4 and 8, each of the suction passages 16 communicates with a through hole 18 provided in a gasket E, and further comprises a tongue-shaped spring provided in a leaf valve D. The intake valve 19 is configured to be closed. No.
10 (a) shows the gasket E, and FIG. 10 (b) shows the leaf valve D.

In each of the counterbore holes 31, a stopper 20 that receives the suction valve 19 of the leaf valve D when it is opened is fitted. As shown in FIGS. 8 and 9, the stopper 20 is narrow so as to provide a gap between the counterbore and the inner wall of the counterbore. An oil passage groove 200 substantially conforming to the side passage hole 33 is formed, and is positioned and held on the cylinder A by the pin 21 for setting this positional relationship. The suction valve 19 of the leaf valve D
Is preferably approximately the same width as the stopper 20 as shown in FIG.

On the other hand, as shown in FIGS. 6 and 7, the distal end of the discharge side passage hole 34 communicates with the through hole 18 'of the gasket E' having the same configuration as that shown in FIG. The end is normally closed by a discharge valve 19 'of a leaf valve D' as shown in FIGS. 6 and 7. The leaf valve D 'has the same configuration as that shown in FIG. 10 (a), that is, a common part.

On the other hand, on the right end face of the cover C, a counterbore 31 ′ is formed at the same position in the radial and circumferential directions as the counterbore 31, and each counterbore 31 ′ has the same shape as the stopper 20. The stopper 20 'having the above structure is fitted and positioned and held on the cover C by a pin 21'. And each counterbore 31 '
Discharge holes 23 are formed at the bottoms of the holes, and these discharge holes 23 are connected in a ring shape by a collective hole 24 as shown in FIG. 6, and arbitrary discharge holes 23 are formed as shown in FIGS. 6 and 7. A discharge passage 25 extending in the axial direction of the cover is connected, and a distal end of the discharge passage 25 communicates with a discharge port member 26 inserted into the cover C to supply high-pressure discharge oil to a not-shown injection system or the like.

In the middle of the discharge passage 25, as shown in FIG.
27 are provided. This relief valve 27 has a spring 27
A needle valve 27b whose valve opening pressure is adjusted by a is provided, and a return hole 260 communicating with the annular chamber 13 is formed at the valve opening position.

If necessary, the cap-shaped piston 3 may be provided with a fine passage hole 300 so as to penetrate the tip of the curvature, whereby a part of the fuel oil in the pressurizing chamber 30 is connected to the guide ring 92. Since it is led to the contact surface, lubricity can be further improved.

The illustration is an example of the present invention, and the gaskets E, E 'may be arranged on both sides so as to sandwich the leaf valves D, D', or conversely, the gaskets E, E 'are omitted. You may.

FIG. 11 and FIG. 12 show a second embodiment of the present invention.
In the second embodiment, on the discharge side, as in FIG. 6 of the first embodiment, a leaf valve D 'is interposed between a cylinder A and a cover C via a gasket E' to form a tongue. The discharge side passage hole 34 and the discharge hole 23 are communicated and blocked by the discharge valve 19 ', but the passage is opened and closed on the suction side by the movement of the piston 3 itself instead of the leaf valve system.

That is, in the second embodiment, the cylinder A and the housing B are connected through the gasket E, and the suction side passage hole 33 is formed in the pressurizing chamber 30 of the cylinder A so that one end communicates with the through hole 18 of the gasket E. Has been established. The opening of the suction side passage hole 33 is closed by the piston peripheral surface when the piston reaches the top dead center position as shown in the upper part of FIG. It is provided so that it can be opened off the peripheral surface. Therefore,
The effective stroke is from the position where the piston moves and closes the suction side passage hole 33 to the top dead center position.

[Operation of the embodiment]

In use, the suction port member 17 is connected to tanks of low-viscosity fuel oil, and the discharge port member 25 is connected to an injection system. The low-viscosity fuel oil passes through the filter 170, flows into the annular chamber 13 from the suction passage 16 via the radial passage 160, and further flows from the annular chamber 13 through the radial passage 160 to each suction passage 1
Flow to 6. At this time, in the first embodiment, the suction valve 19 of the leaf valve D is closed by the spring force, and in the second embodiment, the suction-side passage hole 33 is closed by the piston 3; Does not flow into the pressurizing chamber 30.

When the engine is driven, power is transmitted to a pump shaft F via a drive pulley G, and the pump shaft F rotates while being supported by radial bearings 11 and 12 provided on a housing B and a cover C. Since the annular chamber 13 is always closed on both sides by the oil seals 14 and 15, the low-viscosity fuel oil does not flow into the radial bearings 11 and 12, so the grease is diluted by the cleaning action of the low-viscosity fuel oil. And a good lubrication state can be maintained.

The rotation of the pump shaft F causes the plurality of cap-shaped pistons 3 radially arranged in the cylinder A to reciprocate. That is, each cap-shaped piston 3 is constantly pressed against the eccentric cam portion 9b by the spring 5, so that when the eccentric cam portion 9b rotates from the top dead center to the bottom dead center, the cap-shaped piston 3 is bottom dead from the top dead center. Move to the point side,
As a result, the pressure in the pressurizing chamber 30 becomes negative.

This negative pressure causes a pressure difference with the suction passage 16, and in the first embodiment, the suction valve 19 of the leaf valve D is opened according to the pressure difference. In the second embodiment, the lower end of the piston causes the upper end to be seen through the suction side passage hole 33.
Communicate with By the above operation, in the first embodiment, the low-viscosity fuel oil enters the counterbore 31 from the side of the suction valve 19 and
The air flows into the pressurizing chamber 30 from the suction side passage hole 33 via the suction side passage hole 33, and in the second embodiment, flows directly into the pressurization chamber 30 from the suction side passage hole 33. The discharge valve 19 'is closed by its own spring force and the negative pressure of the pressurizing chamber 30.

The low-viscosity fuel oil that has entered the pressurizing chamber 30 has an eccentric cam portion b of 18
During the 0-degree rotation, the suction stroke occurs, and between 180 and 360 degrees, the compression stroke occurs. In the compression stroke, that is, in the rising stroke of the piston, in the first embodiment, the suction valve 19 is closed by the pressure of the pressurizing chamber, and the discharge valve 19 'is opened. Further, in the second embodiment, the communication between the suction side passage hole 33 and the pressurizing chamber 30 is temporarily reduced or cut off by the rise of the piston 3, and the effective stroke from this position to the top dead center position is the effective stroke.

In any case, the high-viscosity low-viscosity fuel oil enters the counterbore 31 'from the discharge-side passage hole 34 through the side of the discharge valve 19', and is discharged to the discharge hole 23 through the oil passage groove 200, The liquid is delivered from the annular collecting hole 23 to the discharge port member 26 through the discharge passage 25. Therefore, the high-pressure, low-viscosity fuel oil can be injected into the engine cylinder or the like in a well atomized state. When the low-viscosity fuel oil has an abnormally high pressure, the relief valve 27 opens at the discharge pressure, and the high pressure is returned to the annular chamber 13 through the return hole 260.

The cap-shaped piston 3 has a high pressure to compress the low-viscosity fuel oil, and comes into point contact with the guide ring 92 by the reaction force. Since this contact pressure is very high, relative slip does not easily occur between the tip portion of the piston curvature and the guide ring 92, and therefore, abrasion can hardly occur.

The relative rotation between the cap-shaped piston 3 and the pump shaft F is performed by linear contact between the cam body 90 and the metal bush 91,
Since the cam body 90 and the metal bush 91 can be set to appropriate lengths, the overall surface pressure can be reduced. When the pump shaft F rotates at high speed, high heat is generated on the sliding surface between the cam body 90 and the metal bush 91, but the metal bush 91
The low-viscosity fuel oil from the suction port member 17 passes through the annular chamber 13 and is sucked into the respective suction passages 16 via the radial passages 160. That is, the annular chamber 13 functions as a part of the suction passage, and there is always a flow of the low-viscosity fuel oil. Therefore, good cooling and lubrication of the space between the cam body 90 and the metal bush 91, the guide ring 92 and the pump shaft F can be performed.

According to the first embodiment, although the suction function becomes complicated, the suction side passage hole 33 is always smoothly sucked into the pressurizing chamber 30 via the leaf valve D even if the piston 3 is worn out. There is an advantage that the stroke does not change. Second
According to the embodiment, the effective stroke is smaller than that of the first embodiment, but the mechanism can be greatly simplified because the leaf valve on the suction side, the stopper 20, the counterbore 31 and the pin 21 can all be omitted. Can be.

In the drawing, since the pump is composed of three members, the cylinder A, the housing B, and the cover C, the assembly is easy, and when the cam main body 90 is formed separately as the eccentric cam portion 9b, the thickness is increased. The piston stroke, that is, the discharge amount can be changed without changing the pump shaft F by preparing several sets of different cam bodies 90, metal bushes 91, and guide rings 92 and replacing them as appropriate.

[Effects of the Invention] According to the present invention described above, a housing having a suction port and a cover having a discharge port are integrally connected before and after a cylinder having a plurality of pistons, respectively.
A pump shaft having an eccentric cam is supported by the cover and a bearing in a housing, and a low-viscosity fuel is supplied via a suction port between an outer periphery of the eccentric cam and an inner wall of the cylinder and between an outer periphery of the pump shaft behind the eccentric cam and an inner wall of the housing. An annular chamber for storing oil is formed in a series, and an oil seal is provided in the axial direction of the annular chamber to prevent mixing of low-viscosity fuel oil and grease for bearings. A radial passage for sucking low-viscosity fuel oil into the suction hole of each piston is formed as a part of the piston. For this reason, low-viscosity fuel oils such as gasoline and methanol can be used without impairing the lubricity of the bearings.
Further, an excellent effect is obtained in that the piston can be stably pumped by pumping to a high pressure of 70 kgf / cm ² or more without galling or seizure of the piston sliding portion.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional side view showing a first embodiment of a radial pump according to the present invention, FIG. 2 is an exploded perspective view thereof, and FIG. 2a is a partially cutaway exploded perspective view of an eccentric cam portion. Fig. 3 is Fig. 1 II
FIG. 4 is a sectional front view of the cylinder, FIG. 5 is a rear view of a partial cutaway of the housing, FIG. 6 is a front view of a partial cutout of the cover, and FIG. 7 is FIG. FIG. 8 is a sectional view taken along the line VII, FIG.
FIG. 8 is a sectional view taken along line IX-IX in FIG. 8, FIG. 10 (a) is a front view of a relief valve, FIG. 10 (b) is a front view of a gasket, and FIG. 11 is a second embodiment of the present invention. The vertical side view showing the
Figure 12 is a partially enlarged view. A: cylinder, B: housing, C: cover, D, D '...
Leaf valve, E, E ': Gasket, F: Pump shaft, 1, 6: Inner wall, 9b: Eccentric cam, 11, 12: Radial bearing, 13: Annular chamber, 14, 15: Oil seal, 16: Suction passage , 17 ... suction port member, 19 ... suction valve, 19 '... discharge valve,
30 ... pressurized chamber, 33 ... suction side passage hole, 34 ... discharge side passage hole,
160 ... radial passage

Claims (3)

(57) [Claims] 1. A pump having a fixed cylinder and a plurality of pistons radially arranged on the fixed cylinder, wherein the pistons are reciprocated by rotation of an eccentric cam of a pump shaft. A cover having a port is integrally connected before and after a cylinder having a plurality of pistons, respectively, and a pump shaft having an eccentric cam is supported by a bearing in the cover and the housing. A series of annular chambers for storing low-viscosity fuel oil via a suction port is formed between the outer periphery of the pump shaft and the inner wall of the housing between the pump shaft and the rear of the eccentric cam. An oil seal is provided to block the mixing of grease. A radial piston pump for low-viscosity fuel oil, characterized in that a radial passage is formed for sucking the volatile fuel oil into the suction holes of each piston. 2. A pressure chamber which is pressurized by the movement of a piston is provided in a cylinder, and passage holes on a suction side and a discharge side extend in the pressure chamber, and passage holes on the suction side and the discharge side are provided. 2. The radial piston pump for low-viscosity fuel oil according to claim 1, wherein each of the radial piston pumps is connected to an intake passage and a discharge passage via a leaf valve. 3. A cylinder is provided with a pressurizing chamber which is pressurized by the movement of a piston, and the pressurizing chamber has respective passage holes on the suction side and on the discharge side. 2. The radial piston pump for low-viscosity fuel oil according to claim 1, wherein the radial piston pump is connected to the discharge passage through the suction passage, and the passage on the suction side is connected to and blocked from the suction passage on the peripheral surface of the piston.