JPH10288145A - Radial plunger pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent abrasion of a plunger and a member to make contact with it. SOLUTION: Three comparatively shallow ring grooves 95 and one comparatively deep ring groove 96 are formed on a plunger part 93 of a plunger 83, and a polyimide resin made seal ring 97 is engaged with the ring groove 96. The plunger 83 is constituted of a plunger inner 98 as a core bar and a plunger sleeve 99 externally fitted on the plunger inner 98 and forming a contour of the plunger part 93. The plunger inner 98 is made by cutting and molding alloy tool steel and nitrided after vacuum quenching, and the base end side is formed thick and the head end side narrow and stepped. Additionally, the plunger sleeve 99 is made by cutting and working polyimide resin and formed not to make a clearance between itself and the plunger inner 98, and both of them are firmly secured by press fitting and adhesion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a radial plunger pump used for testing a high-pressure fuel pump and the like.
More specifically, the present invention relates to a technique for preventing wear of a plunger and a member that contacts the plunger.

[0002]

2. Description of the Related Art A radial plunger pump is used as a hydraulic pump for generating a high hydraulic pressure in a hydraulic pressure source such as various hydraulic devices. For radial plunger pumps,
There are a fixed cylinder type and a rotary cylinder type. However, the rotary mass is small and the structure is relatively simple.
The fixed cylinder type described in JP-A-175158 or the like is the mainstream. The fixed cylinder type radial plunger pump includes an integral or separate cylinder radially forming a plurality of plunger holes, a plunger slidably held in each plunger hole, and an eccentric camshaft arranged in the center of the cylinder. Consists of An eccentric cam surface of the eccentric camshaft (or a cam roller rotatably fitted to the eccentric portion) is in sliding contact with the end of the plunger,
When the eccentric camshaft rotates by being driven by the prime mover, each plunger is sequentially pushed into the plunger hole, whereby hydraulic oil or the like existing in the plunger hole is supplied to the hydraulic device or the like via the discharge port.

On the other hand, in a fuel injection type spark ignition engine (hereinafter, represented by a gasoline engine) mounted on an automobile or the like, recently, instead of a conventional intake pipe injection type, a low-viscosity gasoline or alcohol or the like is introduced into a combustion chamber. An in-cylinder injection type that directly injects fuel (hereinafter, represented by gasoline) has appeared. In a cylinder injection type gasoline engine, an appropriate amount of gasoline can be injected at an optimal timing in an intake stroke or a compression stroke, so that operation at a lean mixture ratio that cannot be achieved by an intake pipe injection type is realized. As a result, the fuel consumption and the harmful exhaust gas components can be significantly reduced as compared with the intake pipe injection type, and energy saving and air pollution control can be realized at a high level.

[0004]

In a direct injection type gasoline engine, a fuel pump which generates a high fuel pressure (50 kgf / cm ² or more) or a fuel pump discharges from a fuel pump in order to perform accurate fuel injection during a compression stroke. In addition to the need for an electromagnetic fuel injection valve or the like for injecting compressed high-pressure gasoline, it is also required that there be no fuel leakage from fuel pipes and joints. Therefore, with respect to the fuel system, a pressure resistance test is performed for each component, and a leak test is performed when the assembly of the engine is completed. Usually, the above-described radial plunger pump is used for this type of test, but various problems have been encountered in increasing gasoline to a test pressure (for example, 100 kgf / cm ² ).

For example, during operation of the radial plunger pump, the outer peripheral surface of the plunger and the inner peripheral surface of the plunger hole slide back and forth at a high speed. At this time, the plunger has an axial force proportional to the discharge pressure. Appropriate side forces also act.
Therefore, when both the plunger and the cylinder are made of a metal having a high friction coefficient, wear and seizure occur on the sliding surfaces of the two in a very short time in gasoline without lubrication. In order to solve this problem, the inventors have tried to coat the outer peripheral surface of the plunger with molybdenum disulfide or ethylene tetrafluoride. , And it was unable to withstand long-term operation.

On the other hand, in the radial plunger pump, in order to obtain a high discharge pressure, it is necessary to minimize the leakage of gasoline from the gap between the plunger and the plunger hole. However, in order to smoothly perform the above-described reciprocating sliding, a gap between the plunger and the plunger hole must be secured to some extent, and it has been difficult to suppress gasoline leakage. Then, the inventors tried to provide the plunger with a plunger ring for shaft sealing, but in this case, gasoline would be trapped in the gap between the plunger and the plunger hole. Then, the trapped gasoline boils and evaporates in a short time due to the frictional heat between the plunger and the plunger hole, so that the frictional heat of the plunger and the cylinder is not carried away, thereby possibly causing the above-described wear and seizure. There is.

The present invention has been made in view of the above situation,
It is an object of the present invention to provide a radial plunger pump in which a plunger and a member in contact with the plunger are prevented from being worn.

[0008]

According to a first aspect of the present invention, there is provided a cylinder for forming a plurality of plunger holes radially, and a plunger slidably held in each of the plunger holes. An eccentric camshaft disposed at the center of the cylinder, and by rotating the eccentric camshaft, pushes the plunger into the cylinder through an eccentric portion of the eccentric camshaft, whereby the In a radial plunger pump that pressurizes and discharges liquid in a cylinder, the plunger includes a cylindrical plunger part fitted into the plunger hole and a heel part pressed by the eccentric part, and the plunger part is The present invention proposes a plunger inner made of metal and a plunger sleeve made of a low-friction material externally fitted thereto.

According to the present invention, the strength and rigidity of the plunger are kept relatively high by the plunger inner, so that breakage, buckling and the like are less likely to occur. Abrasion and seizing hardly occur due to sliding.

According to the second aspect of the present invention, a cylinder having a plurality of plunger holes formed radially, a plunger slidably held in each of the plunger holes, and an eccentric camshaft disposed at the center of the cylinder By rotating the eccentric camshaft, the plunger is pushed into the cylinder via the eccentric portion of the eccentric camshaft, thereby pressurizing and discharging the liquid in the cylinder. In the pump, the plunger includes a cylindrical plunger portion fitted into the plunger hole and a heel portion pressed by the eccentric portion, and the plunger portion is formed by coating a plunger inner made of metal with a low friction material. Suggest something.

According to the present invention, since the strength and rigidity of the plunger are kept relatively high by the plunger inner, the plunger is less likely to break or buckle, while the plunger hole is coated with a low friction material. Abrasion and seizing hardly occur due to sliding.

According to a third aspect of the present invention, there is provided the radial plunger pump according to the first or second aspect, wherein the plunger inner is formed in a stepped or tapered shape having a narrow distal end and a wide proximal end. .

According to the present invention, the plunger sleeve can be relatively thick at the distal end side of the plunger, so that cracks and the like are unlikely to occur. On the proximal end side, a large shearing force or bending force acts. Also, the breakage of the plunger hardly occurs.

Further, in the invention of claim 4, claims 1 to 3 are provided.
In the radial plunger pump of (1), an annular groove is formed in an outer peripheral portion of the plunger portion.

According to this invention, while the leakage of the liquid is suppressed by the labyrinth effect of the annular groove, when the liquid in the annular groove boils and evaporates due to frictional heat or the like, it becomes bubbles in the suction stroke and enters the plunger hole. It flows out and new liquid flows into the annular groove during the compression stroke.

According to the fifth aspect of the present invention, the first to fourth aspects are provided.
In the radial plunger pump of (1), a ring groove having a depth reaching the plunger inner is formed in an outer peripheral portion of the plunger portion, and the ring groove is formed of a low friction material, and an inner peripheral end of the plunger is engaged with the plunger inner. A ring is proposed in which a plunger ring made of a low friction material is fitted in the ring groove.

According to the present invention, even if a large axial pressure acts on the plunger, the plunger is locked to the plunger inner, so that no excessive pressing force is applied to the plunger sleeve. Further, since the width of the plunger ring is relatively large, the pressing force against the plunger hole becomes appropriate.

Further, according to the invention of claim 6, according to claims 1 to 5,
In this radial plunger pump, a shoe made of a low-friction material is fixed to an end of a heel portion of the plunger inner.

According to the present invention, since the contact partner of the cam shaft or the cam roller is a shoe made of a low friction material,
Wear and seizure of the contact surface are less likely to occur.

According to a seventh aspect of the present invention, there is provided the radial plunger pump according to the sixth aspect, wherein an outer periphery of the shoe is chamfered in an arc shape.

According to the present invention, stress does not concentrate on the outer peripheral end of the shoe, and the durability is less likely to be reduced due to cracks or the like.

Further, in the invention of claim 8, according to claims 1 to 5,
In the radial plunger pump of (1), an end of the heel portion of the plunger inner is coated with a low friction material.

According to the present invention, since the contact partner of the camshaft or the cam roller is a coated low-friction material, wear and seizure of the contact surface hardly occur.

In the ninth aspect of the present invention, the first to eighth aspects are provided.
Radial plunger pump, a plunger spring which is fitted to the cylinder and presses the plunger against the eccentric camshaft, and is interposed between the plunger spring and the plunger, and a pressing force of the plunger spring is provided. To the plunger, and a contact area between the plunger and the spring guide is reduced.

According to the present invention, the frictional resistance between the plunger and the spring guide is reduced, so that the plunger rotates smoothly during operation.

According to a tenth aspect of the present invention, there is provided the radial plunger pump according to the ninth aspect, wherein the spring guide is formed of a low friction material.

According to the present invention, the frictional resistance between the plunger and the spring guide becomes smaller, so that the plunger rotates more smoothly during operation.

[0028] According to the eleventh aspect of the present invention, in the first aspect,
In the radial plunger pump of No. 10, the physical properties of the low friction material are as follows: Compressive strength: ≧ 1,200 kgf / cm ² (at 23 ° C.) Dynamic friction coefficient: ≦ 0.25 (at PV = 500 kgf / cm ² · m / mi)
n), ≦ 0.08 (at PV = 3,000 kgf / cm ² · m / min) Limit PV value: ≧ 3,000 kgf / cm ² · m / min Bending strength: ≧ 1,800 kgf / cm ² (at 23 ° C) Suggest something.

According to the twelfth aspect of the present invention, the first to the fifth aspects are described.
In the eleventh radial plunger pump, it is proposed that the low friction material is polyimide.

According to the eleventh or twelfth aspect of the present invention, since a low friction material is used for the plunger sleeve, shoe, or coating material to be fitted / fixed, high rigidity is ensured as the plunger and smooth operation is performed. In addition to the realization, the generation of wear and frictional heat is suppressed, the endurance withstands extreme pressure and the like, and the bending deformation hardly occurs.

[0031]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a side view of a high-pressure gasoline supply system equipped with a radial plunger pump (hereinafter abbreviated as a pump) according to the present invention. In this embodiment,
For convenience of explanation, the left side of FIG.

As shown in FIG. 1, in the high-pressure gasoline supply system, a pump 1 and an electric motor 2 are mounted on a gantry 3 made of a steel plate, and the rotational force of the electric motor 2 is supplied through a rubber coupling 4 to the pump. 1 is transmitted. In FIG. 1, reference numeral 5 denotes legs, which are attached to the four lower corners of the gantry 3 via cushions 6 made of anti-vibration rubber. Reference numeral 7 denotes a steel plate pump bracket, and reference numeral 8 denotes a steel mesh coupling cover, which are fixed to the upper surface of the gantry 3 by welding, bolts, or the like. In addition, a suction port 9 is provided on the upper surface of the pump 1 before and after.
And a discharge port 10 are formed. A low pressure gasoline pipe 12 from a gasoline storage tank (not shown) is connected to the suction port 9 via a joint 11, and a discharge port 10
Is connected to a high-pressure gasoline pipe 14 to a pressure tester (not shown) via a joint 13.

FIG. 2 is a longitudinal sectional view showing the internal structure of the pump 1. As shown in the figure, the outer shell of the pump 1 has a main housing 21, a suction side housing 22, It is formed from the side cover 23.

An eccentric camshaft 32 is rotatably held at the axis of the main housing 21 via a pair of tapered roller bearings 31. In FIG. 2, 33 is a distance collar, 34 is a bearing nut, and 35 is a lock washer. An O-ring holder 3 provided for holding an O-ring 36 is provided on the rear end face of the main housing 11.
7 is bolted, and a cap seal holder 39 for holding a cap seal 38 is bolted to a rear end surface of the O-ring holder 37. The two tapered roller bearings 31 are lubricated with grease, and the penetration of dust and water into the grease is prevented by the O-ring 36 and the cap seal 39.

An annular collective path 41 communicating with the discharge port 10 is provided in the main housing 21.
Communication passages 4 for communicating with the pump unit to be described later
2 are formed. A seal flange 44 and an O-ring holder 45 are bolted to the front end surface of the main housing 11 so that a pair of cap seals 4 are formed.
6 and an O-ring 47 are held. The cap seal 46 and the O-ring 47 are
1. Prevent gasoline from entering the lubricating grease.

FIG. 2 and FIG. 3 (sectional views of steps AA in FIG. 2)
As shown in FIG. 5, the suction side housing 22 has a cylindrical shape, and its front and rear end portions 51 and 52 have annular grooves 53, on the rear end surface of the side cover 23 and the front end surface of the main housing 21.
The liquid chambers 56 are filled with gasoline 55. In the drawing, 57 is an O-ring for liquid sealing, 58 is a bolt for fastening the suction side housing 22 and the side cover 23 to the main housing 21, and 59 is a drain plug.

In the liquid chamber 56, a compression mechanism including seven radially arranged pump units 61 and a cam roller 63 externally fitted to the eccentric portion 62 of the eccentric cam shaft 32 is provided. The pump unit 61 is bolted to the front end face of the main housing 21. The cam roller 63 is held by an eccentric portion 62 of the eccentric cam shaft 32 via a needle roller 64 and an inner ring 65 thereof. In the case of the present embodiment, the inner race 6 of the needle roller 64
In No. 5, the inner peripheral surface and the outer peripheral surface are coated with molybdenum disulfide, and the coefficient of friction between the eccentric portion 62 and the needle roller 64 is extremely small. In the figure, reference numeral 66 denotes a thrust ring for positioning the needle roller 64 and the inner ring 65 in the left-right direction, and is fitted to the eccentric portion 62 of the eccentric cam shaft 32.

FIG. 4 shows the thrust ring 66 in a perspective view. The thrust ring 66 of the present embodiment is made of a highly lubricated nylon resin containing a compound such as carbon, and has four arc grooves 67 formed in the inner peripheral surface thereof along the axial direction, and one side surface thereof. These arc grooves 6
Four rectangular grooves 68 are formed radially so as to be continuous with.

A circular window hole 71 is formed in the center of the side cover 23, and an observation window 73 made of tempered glass is bolted to the rear end face of the side cover 23 via a glass holder 72. In the figure, reference numeral 74 denotes an O-ring for liquid sealing.

FIG. 5 shows a vertical section of the pump unit 61. As shown in FIG.
Is a cylinder 82 having a plunger hole 81 and a plunger 83 slidably held in the plunger hole 81.
And a plunger spring 84 for pressing the plunger 83 against the cam roller 63 are main components. The cylinder 82 has a built-in suction-side check valve 87 and a discharge-side check valve 88, both of which are composed of steel balls 85 and conical springs 86. In the figure, 89 is a screw-in valve seat,
90 is a spring guide interposed between the plunger 83 and the plunger spring 84, 91 is a C-shaped retaining ring,
Reference numeral 92 denotes an O-ring for liquid sealing. In the case of the present embodiment, the spring guide 90 is formed by cutting a polyimide resin having a low coefficient of friction, and the inner diameter of the penetrating portion of the plunger 83 is made larger than the outer diameter of the plunger 83.
The contact area between the plunger 83 and the spring guide 90 is reduced.

FIG. 6 shows a half longitudinal section of the plunger 83. The plunger 83 includes a cylindrical plunger portion 93 fitted into the plunger hole 81 and a disk-shaped heel portion 94 in contact with the cam roller 63. The plunger portion 93 includes a plurality of relatively shallow plungers (this embodiment). Then
Three) annular grooves 95 and one relatively deep ring groove 96 are formed, and a seal ring 97 made of a polyimide resin shown in perspective in FIG. still,
The seal ring 97 corresponds to the depth of the ring groove 96,
A relatively narrow one is used.

The plunger 83 includes a plunger inner 98 serving as a core metal, and a plunger sleeve 99 which is fitted to the plunger inner 98 to form an outer shell of the plunger portion 93. The plunger inner 98 is formed by cutting and forming an alloy tool steel (in the case of the present embodiment, SKD type 1), performing a nitriding treatment after vacuum quenching, and has a large base end side (heel part 94 side) and a distal end side. It is formed with a thin step. Further, the plunger sleeve 99 is formed by cutting a polyimide resin, and is formed so that there is no gap between the plunger sleeve 99 and the plunger inner 98, and both are firmly fixed by press-fitting and bonding (press-fitting after applying the adhesive). .
The above-mentioned annular groove 95 is formed in the plunger sleeve 99, but the inner peripheral portion of the ring groove 96 is in a form to enter the plunger inner 98.

In the present embodiment, the polyimide resin as a material of the seal ring 97 and the plunger sleeve 99 has the following physical properties.

Compressive strength: ≧ 1,200 kgf / cm ² (at 23 ° C.) Dynamic friction coefficient: ≦ 0.25 (at PV = 500 kgf / cm ² · m / mi)
n), ≦ 0.08 (at PV = 3,000 kgf / cm ² · m / min) Limit PV value: ≧ 3,000 kgf / cm ² · m / min Bending strength: ≧ 1,800 kgf / cm ² (at 23 ° C) Tensile strength Length: ≧ 1,500 kgf / cm ² (at 23 ℃), ≧ 500 kgf /
cm ² (at 250 ° C.) Continuous use temperature: ≧ 250 ° C. Linear expansion coefficient: ≦ 4.0 × 10 ⁻⁵ cm / cm / ° C. Hereinafter, the operation of the gasoline pressurizing system according to the present embodiment will be described.

When conducting a pressure test of an automobile fuel system or the like, the test operator sets the device under test on the pressure test machine connected to the high-pressure gasoline supply system, and then starts the motor 2 via a control device (not shown). I do. Then, the eccentric camshaft 32 of the pump 1 connected to the electric motor 2 is rotationally driven, whereby the cam roller 63 fitted to the eccentric portion 62 of the eccentric camshaft 32 eccentrically rotates with a predetermined eccentric amount, and The plunger 83 of the pump unit 61 is sequentially pushed into the plunger hole 81 of the cylinder 82. At this time, since the cam roller 63 is rotatably held by the eccentric portion 62 via the needle roller 64, the cam roller 63 rotates in the opposite direction to the eccentric portion 62 by an amount equal to the eccentric rotation amount, and It hardly slides with the heel portion 94.

On the other hand, the cam roller 6
Due to non-uniformity of the contact pressure at the time of being pushed by 3, a slight rotational force acts on the plunger hole 81. In the present embodiment, the spring guide 90 is formed of polyimide resin, and the contact area between the plunger 83 and the spring guide 90 is reduced.
The sliding resistance between the plunger 83 and the spring guide 90 becomes extremely small, and the plunger 83 rotates gradually and smoothly by the rotational force. As a result, the plunger 83
The heel portion 94 of the cam roller 63
, So that uneven wear does not occur.

In the pump unit 61, the plunger 83
Is pushed in, the gasoline accumulated in the plunger hole 81 is pressurized, and when a predetermined pressure (50 kgf / cm ² or more in this embodiment) is reached, the discharge side check valve 88 communicates with the communication passage 42. Flows into. High pressure gasoline
From the communication path 42, it reaches the discharge port 10 via the collecting path 41, and is supplied to the pressure resistance tester via the high-pressure gasoline pipe 14. When the cam roller 63 separates from the cylinder 82, the plunger 83
4, the gasoline 55 in the liquid chamber 56 is displaced from the suction-side check valve 87 through the plunger hole 8.
1 flows into. Then, by this operation being sequentially performed by the seven pump units 61, the gasoline 55 in the liquid chamber 56 is continuously pressure-fed to the pressure resistance tester, and a high-precision pressure resistance test is realized.

When the gasoline pressurizing system is operated for a long period of time, the non-volatile components in the gasoline are solidified to form sludge, and dust is introduced into the gasoline from the outside (such as a gas inlet of a gasoline storage tank). May invade. When the sludge or dust is caught as foreign matter in the needle roller 64 (a gap between the cage and the roller), the needle roller 64 may not roll for a moment as described above.

In this case, in this embodiment, since the coefficient of friction between the eccentric portion 62 of the inner ring 65 and the needle roller 64 is extremely small due to the coated molybdenum disulfide, the rotation of the cam roller 63 with respect to the eccentric portion 62 is small. Is secured. That is, as shown in FIG. 8, the cam roller 63 and the needle roller 64 are integrally rotated with respect to the inner ring 65, or as shown in FIG. By rotating the eccentric portion 62 integrally with the eccentric portion 62, the cam roller 63 rotates in the opposite direction with respect to the eccentric portion 62 by an amount equal to the amount of eccentric rotation.

As a result, sliding between the outer peripheral surface of the cam roller 63 and the heel portion 94 of the plunger 83 is unlikely to occur, and wear, seizure, etc., which occur in the conventional device, are prevented. In addition, the rolling failure of the needle roller 64 due to foreign matter is as follows.
Normally, the flow is canceled in a very short time by the flow of gasoline 55 accompanying the operation of the apparatus, and thereafter, the cam roller 63 rotates smoothly due to the rolling of the needle roller 64. In the present embodiment, the inner and outer peripheral surfaces of the inner ring 65 are coated with molybdenum disulfide, but may be coated with ethylene tetrafluoride or the like, or the inner ring 65 itself may be made of a nylon resin or an ethylene tetrafluoride resin. It may be made of a polyimide resin or the like, and the same effect can be obtained in these cases.

On the other hand, if sludge or dust is mixed in the gasoline, the gasoline 55 must be replaced and the pump 1 must be cleaned in order to prevent the above-mentioned poor rotation of the needle roller 64 and the inflow of foreign matter into the device under test. . In addition, when the cam roller 63, the plunger 83, and the like malfunction, it is necessary to stop the device and perform disassembly and repair before the damage occurs. At this time, in the present embodiment, the test operator looks into the observation window 73 and obtains the result shown in FIG. 10 (B in FIG. 2).
As shown in arrow view), the cleanliness of gasoline and the operation state of the mechanical parts can be easily confirmed, and appropriate processing can be promptly performed.

On the other hand, in the present embodiment, the flow of gasoline in the needle roller 64 is promoted by the action of the arc groove 67 and the rectangular groove 68 formed in the thrust ring 66, and the seizure of the needle roller 64, etc. Is prevented. That is, when the thrust ring 66 is rotated together with the eccentric camshaft 32 by the operation of the apparatus, as shown in FIG.
As a result, the gasoline in the arc groove 67 flows into the rectangular groove 68. Thereby, in the needle roller 64, gasoline is supplied to the cam roller 63 and the thrust ring 66.
After flowing in from a gap or the like, it flows toward the arc groove 67 side. As a result, the relatively low temperature gasoline 55 in the liquid chamber 56 is constantly circulated through the needle roller 64, and the wear and seizure of the needle roller and the like due to the stagnation of the gasoline described above are prevented.

Next, the plunger 83 will be described. When the apparatus is operated, the plunger 83 is pushed into the plunger hole 81 of the cylinder 82 by the cam roller 63 which rotates eccentrically, and a large axial force acts on the plunger 83 in accordance with the fuel pressure on the discharge side. A large bending force acts on the plunger 93 depending on the positional relationship of the 83 with the heel 94 and the like. However, in the present embodiment, a high-strength alloy tool steel is used as the material of the plunger inner 98, and the base end side has a large step, so that even when the plunger portion 93 is used for a long period of time, the plunger portion 93 is formed. No bending deformation.

The plunger 83 is inserted into the plunger hole 81.
When sliding inside, some amount of frictional heat is generated, and the temperature of gasoline existing between the two rises. But,
In the present embodiment, three annular grooves 95 are provided in the plunger portion 93.
Is formed, the generation of frictional heat is suppressed by reducing the number of sliding surfaces, and at the same time, when gasoline is boiled or vaporized in the annular groove 95, this is
And acts to cool the plunger 83.

FIGS. 12 and 13 show enlarged vertical cross-sections of the cylinder 82 and the plunger 83 near the annular groove 95. As can be seen from FIG. Along with the rapid expansion of the volume, air bubbles are discharged into the plunger hole 81 (upper side in the figure) during the suction stroke of the plunger 83.
Thereby, in the annular groove 95, as shown in FIG.
New gasoline flows in during the compression stroke of the plunger 83,
The temperatures of the cylinder 82 and the plunger 83 decrease.

Since the pump unit 61 generates a very high pressure as described above, gasoline leakage from the cylinder 82 poses a problem. Therefore, the shaft seal between the plunger 83 and the plunger hole 81 depends on the labyrinth sealing action by the annular groove 95 and the seal ring 97 fitted in the ring groove 96, and the liquid seal of the other parts is an O-ring. Has been done by The seal ring 97 is pressed against the wall surface of the plunger hole 81 by the back pressure. However, if the pressing force F is excessive, the wall surface of the plunger hole 81 is worn by operation for a long period of time. In addition, when the pressing force F is large, the plunger 83 becomes difficult to rotate, and the heel portion 94 may be unevenly worn. However, in the present embodiment, by making the ring groove 96 deep and using the narrow seal ring 97, the seal ring 97 is prevented from being strongly pressed against the wall surface of the plunger hole 81,
As a result, the plunger 83 is easily rotated, and uneven wear of the heel portion 94 is less likely to occur.

As shown in FIG. 14, the seal ring 97
Assuming that the inner diameter is D1, the outer diameter is D2, the thickness is t, and the pressure of gasoline in the compression stroke is P (kgf / cm ² ), the pressing force F (kgf / cm ² ) of the seal ring 97 against the plunger hole 81 is It is obtained by the following equation.

[0059] F = P × ((π / 4) × D1 2 × t) × t / ((π / 4) × D2 2 × t) = P × (D1 2 / D2 2) × t in this embodiment In the seal ring 97, D1 is made sufficiently smaller than D2 and the thickness t is made relatively large (2 mm or more), so that the pressing force F does not become unnecessarily large. The wear on the wall was minimized. Further, since the inner peripheral portion of the ring groove 96 enters the plunger inner 98 and the inner peripheral side of the seal ring 97 is held by the plunger inner 98, high pressure acts on the seal ring 97 during the compression stroke of the pump unit 61. However, the plunger sleeve 99 does not buckle.

The description of the specific embodiment has been completed.
The present invention is not limited to the embodiments described above.
For example, FIGS. 15 and 16 show a plunger 83 in which a shoe 100 made of polyimide resin is attached to a heel portion 94.
Is shown in a half vertical section.

The plunger 83 shown in FIG.
A circular holding recess 101 is formed in the center portion of the disk, and a disc-shaped shoe 100 is embedded in the holding recess 101. The shoe 100 is provided with a chamfer 103 having a radius R (1.5 mm in this embodiment) on an outer peripheral portion thereof,
It is firmly fixed to the holding recess 101 by press-fitting and bonding. By employing this plunger 83,
The cam roller 63 comes into contact with the shoe 100 having a small coefficient of friction, and the cam roller 63 and the shoe 100 hardly wear even after a long-term operation. Further, the shoe 100 is pressed by a large force from the cam roller 63 during the compression stroke of the pump unit 61. However, the action of the chamfer 103 prevents stress from being concentrated on the outer peripheral portion, thereby preventing cracking or chipping of the portion.

The plunger 83 shown in FIG.
A cylindrical holding shaft 104 is formed at the center of the shaft, and an annular shoe 100 is fitted to the holding shaft 104. Also in this example, the outer periphery of the shoe 100 is chamfered 103, and the holding shaft 10
4 is firmly fixed. Also in this example, the action on the cam roller 63 and the plunger 83 is the same as that in FIG.

In the above embodiment, alloy tool steel (SKD or the like) is used as the material of the plunger inner 98, but nickel chrome molybdenum steel (SNCM3 or SNCM3) is used.
CM or other high-strength steel types such as bearing steel (SUJ2 or the like) or high-speed tool steel (SKH9 or the like). Also,
In the above embodiment, the present invention is applied to a gasoline pressurizing system. However, the present invention may be applied to a radial plunger pump used for pressurizing gasohol (a mixture of gasoline and alcohol) or light oil. In addition, the specific configuration of the radial plunger pump, the shape of each component, and the like can be appropriately changed without departing from the spirit of the present invention.

[0064]

As described above, according to the first aspect of the present invention, a cylinder having a plurality of plunger holes formed radially, a plunger slidably held in each of the plunger holes, Having an eccentric camshaft disposed at the center, by rotating the eccentric camshaft, pushing the plunger into the cylinder through an eccentric portion of the eccentric camshaft, whereby
In a radial plunger pump for pressurizing and discharging liquid in the cylinder, the plunger includes a cylindrical plunger part fitted into the plunger hole and a heel part pressed by the eccentric part, and the plunger part Since the plunger sleeve made of a low friction material is externally fitted to a plunger inner made of metal, the strength and rigidity of the plunger are kept relatively high by the plunger inner, so that the plunger is less likely to break or buckle. Since the plunger sleeve made of a low friction material slides in the hole, wear and seizure hardly occur.

According to the second aspect of the present invention, a cylinder having a plurality of plunger holes formed radially, a plunger slidably held in each of the plunger holes, and an eccentric disposed at the center of the cylinder Rotating the eccentric camshaft to push the plunger into the cylinder through an eccentric portion of the eccentric camshaft, thereby pressurizing and discharging the liquid in the cylinder. In the radial plunger pump, the plunger includes a cylindrical plunger part fitted into the plunger hole and a heel part pressed by the eccentric part, and the plunger part includes a low friction material on a plunger inner made of metal. Due to the coating, the plunger has relatively high strength and rigidity due to the plunger inner. While breakage and buckling or the like is less likely to occur in order to sag, low-friction material coated is with wear and burn hardly occurs to slide the plunger hole.

According to the invention of claim 3, according to claim 1,
In the radial plunger pump of the second aspect, since the plunger inner is formed in a stepped or tapered shape having a narrow distal end and a large proximal end, the plunger sleeve can have a relatively large thickness at the distal end of the plunger. While cracks etc. are unlikely to occur on the proximal end side,
Even if a large shearing force or bending force acts, breakage or the like of the plunger hardly occurs.

Further, according to the invention of claim 4, according to claim 1,
In the radial plunger pumps of Nos. 1 to 3, since the annular groove is formed in the outer peripheral portion of the plunger portion, the leakage of the liquid is suppressed by the labyrinth effect of the annular groove, while the liquid in the annular groove boils due to frictional heat or the like.・ When it evaporates,
This becomes bubbles in the suction stroke and flows out into the plunger hole, and new liquid flows into the annular groove in the compression stroke, and the plunger and the cylinder are easily cooled.

According to the invention of claim 5, according to claim 1,
In the radial plunger pumps of Nos. 1 to 4, a ring groove having a depth reaching the plunger inner is formed in an outer peripheral portion of the plunger portion, and the ring groove is made of a low friction material, and an inner peripheral end thereof is engaged with the plunger inner. Since the plunger ring made of a low friction material is fitted in the ring groove, even if a large axial pressure acts on the plunger ring, the plunger ring is locked to the plunger inner. As a result, no excessive pressing force is applied to the plunger sleeve. Further, since the width of the plunger ring is relatively large, the pressing force against the plunger hole becomes appropriate.

According to the invention of claim 6, according to claim 1,
In the radial plunger pumps of (1) to (5), since a shoe made of a low friction material is fixed to the end of the heel portion of the plunger inner, the contact partner of the cam shaft or the cam roller becomes the shoe of the low friction material, Wear and seizure hardly occur.

Further, according to the invention of claim 7, according to claim 6,
In the radial plunger pump of (1), since an arc-shaped chamfer is formed on the outer periphery of the shoe, stress is not concentrated on the outer peripheral end of the shoe, and the durability is less likely to be reduced due to cracks or the like.

According to the invention of claim 8, according to claim 1,
In the radial plunger pumps of Nos. 1 to 5, since the end of the heel portion of the plunger inner is coated with a low friction material, the contact partner of the cam shaft or the cam roller becomes a coated low friction material, so that the contact surface is worn or seized. Etc. hardly occur.

Further, according to the ninth aspect of the present invention, the first aspect of the present invention is provided.
In the radial plunger pumps of Nos. 1 to 8, a plunger spring which is externally fitted to the cylinder and presses the plunger toward the eccentric cam shaft is interposed between the plunger spring and the plunger. A spring guide for transmitting the pressing force to the plunger is further provided, and the contact area between the plunger and the spring guide is reduced, so that the frictional resistance between the plunger and the spring guide is reduced. And the uneven wear of the heel portion is less likely to occur.

According to the tenth aspect of the present invention, in the radial plunger pump of the ninth aspect, since the spring guide is formed of a low friction material, the frictional resistance between the plunger and the spring guide becomes smaller, and the plunger during operation is reduced. Rotate more smoothly, and uneven wear of the heel portion is further less likely to occur.

According to the eleventh aspect of the present invention, in the radial plunger pump according to the first to tenth aspects, the physical properties of the low friction material are as follows: Compressive strength: ≧ 1,200 kgf / cm ² (at 23 ° C.) Dynamic friction coefficient : ≦ 0.25 (at PV = 500 kgf / cm ² · m / mi
n), ≦ 0.08 (at PV = 3,000 kgf / cm ² · m / min) Limit PV value: ≧ 3,000 kgf / cm ² · m / min Bending strength: ≧ 1,800 kgf / cm ² (at 23 ° C) The use of low-friction material for the plunger sleeve, shoe, or coating material that is externally fitted / fixed ensures high rigidity and smooth operation as a plunger, and also reduces wear and friction heat. Occurrence is suppressed, extreme pressure and the like are well endured, and bending deformation hardly occurs.

According to the twelfth aspect of the present invention, in the radial plunger pump according to the first to eleventh aspects, the low friction material is made of polyimide. The use of a low friction material for the plunger ensures high rigidity as well as smooth operation,
The generation of wear and frictional heat is suppressed, and it withstands extreme pressure, etc.
In addition, bending deformation hardly occurs.

[Brief description of the drawings]

FIG. 1 is a side view showing a gasoline pressurizing system according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing the internal structure of the radial plunger pump.

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

FIG. 4 is a perspective view of a thrust ring.

FIG. 5 is a longitudinal sectional view showing the internal structure of the pump unit.

FIG. 6 is a longitudinal sectional view showing a structure of a plunger.

FIG. 7 is a perspective view of a seal ring.

FIG. 8 is an explanatory diagram showing an operating state of the inner ring when the rolling of the needle roller is defective.

FIG. 9 is an explanatory diagram showing an operating state of the inner ring when the rolling of the needle roller is defective.

FIG. 10 is a view taken in the direction of arrow B in FIG. 2;

FIG. 11 is an explanatory diagram showing an operation of a thrust ring.

FIG. 12 is an explanatory view showing an operation of an annular groove.

FIG. 13 is an explanatory view showing the operation of the annular groove.

FIG. 14 is an enlarged view showing a seal ring attaching portion of the plunger.

FIG. 15 is a half cut longitudinal sectional view showing a modified embodiment of the plunger.

FIG. 16 is a half cut longitudinal sectional view showing a modified embodiment of the plunger.

[Explanation of symbols]

 Reference Signs List 1 radial plunger pump 2 electric motor 9 suction port 10 discharge port 21 main housing 22 suction side housing 23 side cover 32 eccentric camshaft 41 collective path 42 communication path 61 pump unit 61 62 eccentric part 63 cam roller 64 needle roller 65 inner ring 66 thrust ring 67 Circular groove 68 Rectangular groove 81 Plunger hole 82 Cylinder 83 Plunger 87 Suction side check valve 88 Discharge side check valve 93 Plunger part 94 Heel part 95 Annular groove 96 Ring groove 97 Seal ring 98 Plunger inner 99 Plunger sleeve 100 Shoe

Continued on the front page (72) Inventor Kenzo Iwano 3-7-5 Misakicho, Chiyoda-ku, Tokyo

Claims (12)

[Claims] An eccentric camshaft disposed at a center of the cylinder; a cylinder for radially forming a plurality of plunger holes; a plunger slidably held in each of the plunger holes; By rotating a camshaft, the plunger is pushed into the cylinder through an eccentric portion of the eccentric camshaft, whereby a radial plunger pump pressurizes and discharges the liquid in the cylinder. The plunger includes a cylindrical plunger portion fitted into the plunger hole and a heel portion pressed by the eccentric portion, and the plunger portion is formed by externally fitting a plunger sleeve made of a low friction material on a plunger inner made of metal. A radial plunger pump characterized in that: 2. An eccentric system comprising: a cylinder having a plurality of plunger holes radially formed therein; a plunger slidably held in each of the plunger holes; and an eccentric camshaft disposed at the center of the cylinder. By rotating a camshaft, the plunger is pushed into the cylinder through an eccentric portion of the eccentric camshaft, whereby a radial plunger pump pressurizes and discharges the liquid in the cylinder. It is provided with a cylindrical plunger part fitted into the plunger hole and a heel part pressed by the eccentric part, and the plunger part is formed by coating a plunger inner made of metal with a low friction material. Radial plunger pump. 3. The radial plunger pump according to claim 1, wherein the plunger inner is formed in a stepped or tapered shape with a thinner distal end and a thicker proximal end. 4. The radial plunger pump according to claim 1, wherein an annular groove is formed in an outer peripheral portion of the plunger portion. 5. A plunger ring is formed at an outer peripheral portion of the plunger portion to a depth reaching the plunger inner, the ring groove being made of a low-friction material, and an inner peripheral end of which is engaged with the plunger inner. The radial plunger pump according to any one of claims 1 to 4, wherein the radial plunger is fitted. 6. The radial plunger pump according to claim 1, wherein a shoe made of a low-friction material is fixed to an end of the heel portion of the plunger inner. 7. The radial plunger pump according to claim 6, wherein an outer periphery of said shoe is chamfered in an arc shape. 8. The radial plunger pump according to claim 1, wherein an end of the heel portion of the plunger inner is coated with a low friction material. 9. A plunger spring which is fitted to the cylinder and presses the plunger toward the eccentric camshaft; and a plunger spring interposed between the plunger spring and the plunger to reduce a pressing force of the plunger spring. The radial plunger pump according to any one of claims 1 to 8, further comprising a spring guide for transmitting to the plunger, wherein a contact area between the plunger and the spring guide is reduced. 10. The radial plunger pump according to claim 9, wherein said spring guide is formed of a low friction material. 11. The physical properties of the low friction material are as follows: Compressive strength: ≧ 1,200 kgf / cm ² (at 23 ° C.) Dynamic friction coefficient: ≦ 0.25 (at PV = 500 kgf / cm ² · m / mi)
n), ≦ 0.08 (at PV = 3,000 kgf / cm ² · m / min) Limit PV value: ≧ 3,000 kgf / cm ² · m / min Bending strength: ≧ 1,800 kgf / cm ² (at 23 ° C) The radial plunger pump according to claim 1, wherein: 12. The radial plunger pump according to claim 1, wherein the low friction material is polyimide.