JP3173127B2 - Priming pump for fuel supply system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a priming pump of a fuel supply device used for bleeding a fuel path connecting a fuel tank and a fuel injection pump.

[0002]

2. Description of the Related Art As shown in FIG. 2, a fuel supply system for an engine mounted on an automobile includes a fuel tank 1 for storing liquid fuel (hereinafter simply referred to as fuel) and a fuel injection pump 2.
In some cases, a fuel supply pump 3 with a priming pump is provided between them so that air can be removed in the same section.

Conventionally, according to such a fuel supply pump 3, a cam drive type is adopted as a pump system. Specifically, when the pump piston 6 is reciprocated by the camshaft 4 via the tappet roller 5 or the like, the fuel in the fuel tank 1 is consequently discharged to the suction port 7, the suction valve 8, and the pump chamber 9. ,
The structure which is sent to the fuel injection pump 2 through the discharge valve 10 and the discharge port 11 is used.

The priming pump 12 employs a manually operated reciprocating pump. Specifically, a cylinder 13 is detachably mounted on the body 3a (main body) of the fuel supply pump 3, and the cylinder 13 is communicated with a fuel path portion between the suction valve 8 and the pump chamber 9, and 13
Constitutes a pump chamber 14. A plunger 1 having a handle 15 at its head is provided in the cylinder 13.
6 is used in a reciprocating manner. The plunger 16 includes a piston 17 that reciprocates in the cylinder 13 and a rod 18 that connects the piston 17 to the handle 15.

[0005] When performing an air bleeding operation in the fuel path 19 (passage between the fuel tank 1 and the fuel injection pump 2), the handle 15 is gripped with fingers and the piston 1
7 is reciprocated. Then, the pump chamber 14 expands and contracts in accordance with the reciprocating motion of the piston portion 17, and the pump chamber 9 expands and contracts.
Do pump work instead of

As a result, the fuel is supplied from the fuel tank 1 to the fuel injection pump 2 under pressure, and air is removed from the fuel path 19 to the fuel injection pump 2.

By the way, the priming pump 12 of such a fuel supply device is required to fix the plunger 16 in order to prevent other influences when the pump is not used.

Therefore, conventionally, as shown in FIG. 2, a screw shaft 21 protrudes from the tip of the plunger 14, that is, the tip of the piston 17, and a screw hole mating with the screw shaft 21 is formed on the bottom of the cylinder 13. When the air venting operation is completed by providing the plunger 22, the plunger 14 is rotated while being pushed in, the screw shaft 21 and the screw hole 22 are screwed together, and the plunger 14 is fixed.

[0009]

Incidentally, the plunger 16 of the priming pump 12 is provided with a seal 23 for keeping the sliding portion with the cylinder 13 airtight.

However, in the state where the air venting operation has been completed and the fuel has been filled in the downstream fuel path portion after the suction valve 8, there is no place for the fuel to escape because of the seal 23.

For this reason, when the plunger 16 is pressed down by gripping the handle 15 in order to fix the plunger 16 after the air bleeding operation, considerable resistance is generated and it is difficult to tighten.

That is, when the plunger 16 is pushed down, there is no escape area for fuel, so the pressure in the pump chamber 14 increases, and this becomes a force that prevents the plunger 16 from being pushed down. Was difficult to screw into.

As a result, the plunger 16 is in an imperfect state.
May be fixed to the cylinder 13. In particular,
In many cases, the plunger 16 is fixed in a state where the engagement of the threads is small.

In such a state, when the engine (not shown) is in operation, the screw shaft 21
There is a strong demand for improvement since loosening is likely to occur in the fastening portion between the priming pump 12 and the screw hole 22 and the quality of the priming pump 12 is deteriorated.

The present invention has been made in view of such circumstances. It is an object of the present invention to provide a priming pump for a fuel supply device which can easily fix a plunger for which air removal has been completed. Is to do.

[0016]

Means for Solving the Problems] priming pump of the fuel supply apparatus of the present invention in order to achieve the above object, flop
Pump chamber when pump chamber is expanded by reciprocating operation of the langger
Secure the plunger at a position where the pump chamber volume is larger than the volume.
The cylinder is provided with fixing means for
When the pump is not used, the plunger is fixed to the above position by the fixing means .

[0017]

[Action] According to the priming pump of the fuel supply apparatus of the present invention, when obtaining the final working air vent, the plunger,
Pon by reciprocating plunger operation during air bleeding
Pump chamber volume is larger than the pump chamber volume when the pump chamber is expanded.
Is fixed at the position Therefore, the pump when not using the pump
The chamber volume is suitable for plunger reciprocating operation during air bleeding.
The volume of the pump chamber at the time of expansion is increased.

At this time, since the flow of fuel is allowed in the direction from the upstream side of the fuel path to the cylinder with the cylinder as a boundary, the fuel path enters the pump chamber as the volume of the pump chamber increases. Fuel flows in.

As a result, a force which hinders the fixing operation of the plunger does not act on the plunger unlike the related art.

As a result, the plunger can be easily fixed to the cylinder.

Furthermore, the simplicity of the priming pump means that the plunger is securely fixed to the cylinder, thereby preventing a decrease in the fixing force due to the influence of engine vibration and the like, and providing the priming pump with high reliability.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in FIG.

The drawing shows a cross section of the priming pump 30, in which 31 is a cylinder.

The cylinder 31 is configured such that a cap 33 is screwed into an opening on the handle side of a cylindrical housing 32 having a lower end on the installation side and an upper portion on the handle side. Then, inside the cylinder 31, for example, a cylindrical pump chamber 34 having a bottom dead center below the lower surface of the cap 33 and a bottom dead center above the bottom surface of the housing 32.
Is composed . Note that this top dead center is defined as
The piston part 37 of the plunger 36 described later
The pump 34 is reciprocated in the pump chamber 34 and the pump 34 expands and contracts.
Of the piston part 37 when the pump chamber 34 expands when
Location. On the other hand, the bottom dead center is
2 shows the position of the piston part 37 at the time.

At the lower end of the housing 32, a screw shaft portion 35 for installation having a passage 35a communicating with the pump chamber 34 is formed so as to protrude therefrom, which replaces the conventional priming pump shown in FIG. Thus, the priming pump 30 of the present invention is installed on the body 3a of the fuel supply pump 3. Note that the structure of the fuel supply pump 3 is the same as that described in the section of "Prior Art" above, and therefore the description of the structure of the pump 3 will be omitted.

In the cylinder 31, a plunger 36 is provided.
Is provided. The plunger 36 slidably moves a piston portion 37 provided reciprocally in the pump chamber 34, a bottomed cylindrical handle 38 slidably fitted on an upper portion of the housing 32, and the cap 33. It is constituted by a rod portion 39 which penetrates and connects the piston portion 37 and the handle 38 to each other.

The piston portion 37 has a small-diameter portion 37a on the lower side (head side) and a large-diameter portion 37b on the upper side (back side). An oil seal 40 is provided on the outer peripheral portion of the small-diameter portion 37 a to seal between the small-diameter portion 37 a and the inner peripheral surface of the housing 32 .

Thus, the handle 38 is gripped by a finger, and the piston portion 37 is set at a top dead center set below the lower surface of the cap 33 and a bottom dead center set above the bottom surface of the housing 32. When the reciprocating operation is performed so as to slide within the range, the fuel in the fuel tank 1 can be pumped toward the fuel injection pump 2 by the expansion and contraction repeatedly performed in the pump chamber 34.

Reference numeral 41 denotes a return spring for returning the handle 38 interposed between the upper surface of the cap 33 and the inner bottom surface of the handle 37 to a fixed position.
Is an O-ring provided between the outer peripheral surface of the housing 32 and the inner peripheral surface of the handle 38 for preventing dust and the like from entering from outside.

A pressure regulating valve 43 is provided at the head of the piston portion 37. The pressure regulating valve 43 has a substantially dish-shaped valve body 44 disposed on the head surface of the piston portion 37 with the concave side facing downward, and a central portion of the valve body 44 to penetrate the piston portion 37. And a pin 45 fixed to the head surface.

The valve body 44 has an outer diameter slightly smaller than the outer diameter of the oil seal 40. The head of the pin 45 for fixing the valve body 44 has a larger diameter than the outer diameter of the piston portion 37.
An opening / closing piece portion 44a having a small outer diameter and capable of closing a gap 46 between the valve body 42 and the inner peripheral surface of the cylinder 31 by deformation is formed on the outer peripheral portion of the valve body 44. I have. The opening / closing piece 42a is set to have a deformation (opening / closing) characteristic so as to close the gap 46 only when the pressure in the pump chamber 34 becomes high. Thus, during operation of the engine, when the pump piston 6 is operated, the inside of the pump chamber 34 becomes high in pressure due to the operation of the pump piston 6, the opening / closing piece 44a is brought into close contact with the inner peripheral surface of the housing 32, and the pressure is reduced.
The oil seal 40 is prevented from participating in the oil seal 40 (protection of the oil seal 40).

On the surface of the cap 33 facing the pump chamber 34, a circular recess 47 (constituting fixing means) is provided concentrically with the piston portion 37. This recess 47
On the inner peripheral surface, a female screw 48 (constituting fixing means)
Is engraved. Further, between the large-diameter portion 37b and the rod portion 39, a shaft portion 4 having a short axis shape that can be accommodated in the concave portion 47 is provided.
9 (constituting the fixing means). On the outer peripheral surface of the shaft portion 49, a male screw 50 (constituting a fixing means) combined with the female screw 48 is provided.

Thus, at the end of the air bleeding operation, the handle 38 is pushed up and rotated to rotate the male screw 50.
By screwing the female screw 48, the piston 37 is fixed at a position above the position of the top dead center by utilizing the displacement caused by the housing of the shaft 49 with respect to the recess 47.

Next, the operation of the priming pump 30 configured as described above will be described.

It is assumed that the priming pump 30 is installed in the fuel supply pump 3 (shown in FIG. 2) instead of the conventional priming pump.

In this state, when air is evacuated from the fuel passage 19, first, the handle 38 is gripped by a finger and rotated in a direction to loosen the screw, thereby releasing the screwing of the female screw 48 and the male screw 50.

When the restraint of the plunger 36 is released, the piston portion 37 is forcibly taken out of the concave portion 47 and placed at the top dead center of the pump chamber 34.

Next, the piston 38 is reciprocated between the top dead center and the bottom dead center by operating the handle 38 back and forth.

Then, the pump chamber 34 is
The expansion and contraction are repeated in accordance with the movement of the fuel supply pump 3 to perform a pump work in place of the fuel supply pump 3. That is, fuel from the fuel tank 1 is sucked into the fuel path 19 from the suction port 7, and the suction valve 8, the pump chamber 9, the discharge valve 10, the discharge port 11
Is sent to the fuel injection pump 2 by pressure.

As a result, fuel fills the fuel path 19 to the fuel injection pump 2, and the air is vented in the same path.

At this time, since the pressure acting on the pressure regulating valve 43 is low, the opening / closing piece 44a does not come into close contact with the inner peripheral surface of the housing 32, and no sliding resistance that hinders the air venting operation is generated. .

When the plunger 36 is to be fixed after the completion of the air bleeding operation, the handle 38 is rotated in a screw tightening direction while pulling the handle 38 upward.

Then, the external thread 50 and the concave portion 47 of the shaft portion 49 are formed.
The female screw 48 is screwed together, and the shaft portion 49 that has been immediately below the concave portion 47 is gradually housed in the concave portion 47,
The piston portion 37 of the plunger 36 is pushed upward from the top dead center at which expansion and contraction occurs.

Thus, the volume of the pump chamber 34 gradually increases.

Here, the fuel passage 19 allows fuel to flow in the direction from the upstream side of the fuel passage 19 to the cylinder 31 with respect to the point where the cylinder 31 is installed (the fuel supply pump). 3), the fuel flows into the pump chamber 34 as the volume of the pump chamber 34 increases.

This means that the plunger 36 does not
In contrast, no force acts on the plunger 36 to hinder the fixing operation.

That is, the fixing operation can be smoothly performed with a small operation force.

When the handle 38 is turned further during the rotation operation, the entire shaft portion 49 is housed in the concave portion 47 and fixed at a position above the top dead center of the pump chamber 34, and After the fixing work.

Therefore, the plunger 36 can be easily fixed to the cylinder 31. In addition, the simplicity leads to the reliable fixing of the plunger 36 to the cylinder 31. As a result, a decrease in the fixing force due to the influence of engine vibration or the like, that is, the loosening of the screw can be prevented, and high reliability can be prevented. Quality as well as high quality can be provided to the priming pump 30.

FIG. 2B shows another embodiment of the present invention.

In this embodiment, an oil seal as in one embodiment is used.
Instead of fixing the plunger 36 at a position above the top dead center by providing a screw portion above the point where the screw 40 is located, a screw portion is provided below the oil seal 40 so as to be above the top dead center. Is fixed to the plunger 36 at the position shown in FIG.

Specifically, the depth direction of the concave portion 46 is extended,
And the tip of the piston part 37 is extended. A short shaft portion 61 having a screw 60 engraved on an outer peripheral portion is provided at a distal end portion of the extended piston portion 37, and a female screw 62 is provided on an inner peripheral surface of the housing 32 which is above the top dead center of the pump chamber 34. Is provided, the plunger 36 is fixed to the cylinder 31 by screwing the male screw 60 and the female screw 62, and the plunger 36 is arranged above the top dead center of the pump chamber 34.

However, in this figure, the same parts as those of the embodiment are denoted by the same reference numerals, and the description thereof is omitted.

In this case, the same effect as in the embodiment can be obtained.

Further, in such a structure in which the screw portion is provided below the oil seal 40 to fix the plunger 36, the screw portion and the short shaft portion 61 function as a pressure regulator and the pump chamber 34 is provided. Since the high pressure of the oil seal 40 can be cut off to prevent the oil seal 40 from being damaged (such as breakage of the lip), there is an advantage that the pressure regulating valve as in the embodiment is not required.

In the above-described embodiment, the structure in which the plunger is fixed by using a screw is adopted. However, it goes without saying that the present invention may be applied to other fixing structures.

In the above-described embodiment, the lead direction of the screw for fixing the plunger may be the same as or different from the lead direction of the general screw for fixing the cylinder. . In particular, if the direction is the same as the general screw lead direction, the tightening direction and the loosening direction of commonly used screws are the same, so that an uncomfortable feeling in the tightening work of the plunger can be eliminated. Bring.

[0058]

As explained above, according to the present invention,
The plunger for which the air bleeding operation has been completed can be easily fixed.

[Brief description of the drawings]

FIG. 1A is a sectional view showing a priming pump according to an embodiment of the present invention. (B) is sectional drawing which shows the priming pump of other Example of this invention.

FIG. 2 is a sectional view showing a conventional priming pump together with a fuel supply pump.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fuel tank, 2 ... Fuel injection pump, 19 ... Fuel path, 30 ... Priming pump, 31 ... Cylinder, 34
... Pump chamber, 36 ... Plunger, 37 ... Piston, 4
1 ... Return spring, 47 ... Recess, 48 ... Female thread, 49 ... Shaft part, 50 ... Male thread.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F02M 37/16 F02M 37/00

Claims (1)

(57) [Claims] 1. A cylinder installed in a fuel path connecting a fuel tank and a fuel injection pump, and constituting a pump chamber communicating with the fuel path, a cylinder reciprocally provided in the cylinder, A priming pump of a fuel supply device having a manually operated plunger for expanding and contracting the pump chamber by operation.
Oite, when the pump chamber expands due to reciprocating operation of the plunger
At a position where the pump chamber volume is larger than the pump chamber volume
Provided on the cylinder to fix the plunger
And a fixing means for fixing the plunger at the position when the priming pump is not used .