JP2512177Y2 - Fuel injection pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a fuel injection pump such as a Bosch fuel injection pump.

(Prior Art) FIG. 2 shows a Bosch type fuel injection pump which is widely used at present.
The structure that reciprocates the
It has a function of compressing the fuel sucked into 54 by the plunger 52 and discharging it. In the figure, 55 is an oil-filling groove, 56 is a drain groove, and 57 is a lead portion. In the barrel 51 and the plunger 52, in order to prevent abnormal wear of both, it is said that the plunger 52 is made of bearing steel and the barrel 51 is made of nitrided steel. Has been adopted.

By the way, in recent years, attempts have been made to use alcohols such as methanol as fuel, but methanol has a low viscosity (kinematic viscosity: 0.9 cst of methanol, 3.
7cst), when using such fuel, lead
57 The possibility of increased damage such as seizure increases. As a measure to prevent such damage, for example, in the "International Symposium on Introduction of Methanol Vehicles (Pre-lecture Collection)" [Published on February 19, 1987 by the Transportation Economic Center of Japan], a lubrication hole provided on the pump body A method of supplying lubricating oil from an oil supply groove 55 (not shown) is adopted.

(Problems to be solved by the invention) By the way, although the above measures are effective when the fuel injection pump is small, when the fuel injection pump is large, satisfactory results are not always obtained. Instead, according to the experiments by the present inventors, it has been confirmed that abnormal wear occurs in the vicinity of the lead portion 57. This is because as the fuel injection pump becomes larger, the discharge pressure in the pressure chamber 54 rises (for example, 1000 kg / cm ² or more), and in the above method, the lubrication between the lubrication groove 55 and the drain groove 56 is ensured. However, this is because lubrication in the vicinity of the lead portion 57 cannot be sufficiently performed.

The present invention has been made to solve the above-mentioned conventional drawbacks, and the purpose thereof is to prevent the occurrence of abnormal wear near the leads as described above even when alcohol fuel is used. Therefore, it is to provide a fuel injection pump having improved durability.

(Means for Solving the Problems) Therefore, in the fuel injection pump according to the first aspect, in the fuel injection pump that reciprocally drives the plunger in the barrel to discharge the fuel, the plunger includes a plunger main body and the plunger main body. A sleeve made of a self-fluxing alloy that is fitted to the tip of the sleeve, and a lead portion is formed on the outer peripheral portion of the sleeve. A small relief portion is provided, and a pressure groove that opens into the pressure chamber on the tip side is provided between the plunger body and the sleeve.

In the fuel injection pump according to the second aspect of the present invention, a hardened portion such as a TiN coating layer and a beam quenching portion is formed on the sliding contact portion of the lead portion on the inner peripheral portion of the barrel.

(Operation) In the above fuel injection pump, since the sleeve including the lead portion of the plunger is made of a self-fluxing alloy having good wear resistance, abnormal wear can be prevented even when lubrication is insufficient. The durability can be improved. Also, the barrel repeats expansion and contraction due to pressure rise and fall in the pressure chamber, but since the pressure groove is provided, the outer diameter of the sleeve also expands and contracts at the same time,
As a result, it is possible to prevent a large variation in the gap between the barrel and the sleeve, prevent foreign matter from being caught between the barrel and the sleeve, or prevent the plunger from being caught in the sleeve. This also improves durability. . Moreover, since the pressure groove is formed between the plunger body and the sleeve, it is possible to suppress the volume of the pressure groove to a necessary minimum, and as a result, it is possible to prevent a decrease in the volumetric efficiency of the pump.

Further, when the structure according to the second aspect is adopted, abnormal wear on the inner surface side of the barrel can be eliminated, so that the durability can be further improved.

Embodiment Next, a specific embodiment of the fuel injection pump of the present invention will be described in detail with reference to the drawings.

In FIG. 1, reference numeral 1 is a barrel, and 2 is a plunger. The plunger 2 is reciprocally driven in the barrel 1, whereby the fuel is sucked into the pressure chamber 4 from the fuel supply / discharge hole 3 and the earned fuel is collected. It is designed so that it can be compressed by the plunger 2 and discharged. The plunger 2 is composed of a plunger body 5 and a cylindrical sleeve 6 fitted to the tip of the plunger body 5. Between the plunger body 5 and the sleeve 6, a pressure chamber 4 is formed. An annular pressure groove 7 is formed which opens to the. Also, the sleeve 6
In the outer peripheral portion of the taper-shaped relief portion 8 in order from the tip side.
And a lead portion 9 are formed. The sleeve 6 is fitted and fixed to the plunger body 5 by shrink fitting, press fitting, or the like. Further, in the figure, 10 indicates an oil-filling groove and 11 indicates a drain groove, respectively. However, in the inner peripheral portion of the barrel 1, a TiN coating layer 12 as a hardened portion is formed at a position above the drain groove 11. Has been done.

The plunger body 5 is made of bearing steel, and the sleeve 6 is made of a self-fluxing alloy (for example, Ni-Cr system), while the barrel 1 is made of nitrided steel.

In the above-described fuel injection pump, in the plunger 2, the sleeve 6 including the lead portion 9 is made of a self-fluxing alloy having good wear resistance, so abnormal wear is caused even when lubrication is insufficient. It can be prevented and its durability can be improved. Further, the pressure groove 7 is provided and the relief portion 8 is formed around the pressure groove 7, which brings about the following advantages. That is, the pressure rise in the pressure chamber 4,
Although the barrel 1 repeatedly expands and contracts due to the decrease, since the pressure groove 7 is provided, the outer diameter of the sleeve 6 also expands and contracts at the same time. It is possible to prevent the gap between the sleeve 6 and the sleeve 6 from fluctuating greatly, and to prevent foreign matter from being caught between the two 1, 6 or the plunger 2.
This means that the hugging phenomenon can be prevented, and this also makes it possible to improve the durability. Moreover, since the pressure groove 7 is formed between the plunger main body 5 and the sleeve 6 as in the embodiment, the volume of the pressure groove 7 can be suppressed to a necessary minimum, and as a result, the volume of the pump can be reduced. There is also an advantage that the reduction in efficiency can be prevented.

Moreover, since the TiN coating layer 12 as a hardened portion is formed on the inner peripheral surface of the barrel 1, abnormal wear can be prevented from occurring at this portion, and in this respect as well, the pump life can be improved. . The TiN coating layer 12
The drain groove 11 is formed above the drain groove 11 because the lower portion of the drain groove 11 can be treated with oil from the oil groove 10 as in the conventional case.

An embodiment of the fuel injection pump of the present invention has been described above, but the fuel injection pump of the present invention is not limited to the above, and various modifications can be carried out. For example, as the hardened portion on the inner peripheral surface of the barrel 1, a striped hardened portion formed by a laser beam or an electron beam may be formed instead of the TiN coating layer 12. in this case,
As a form of the quenching part, although not shown, a plurality of quenching parts extending linearly in the axial direction are provided at predetermined intervals, or a plurality of quenching parts are arranged spirally at predetermined intervals. It is possible to

(Effect of the Invention) As described above, in the fuel injection pump according to the first aspect, in the fuel injection pump, the sleeve including the lead portion of the plunger is made of a self-fluxing alloy having good wear resistance. Therefore, abnormal wear can be prevented and its durability can be improved even in a use situation where sufficient lubrication cannot be obtained such as when alcohol is used as fuel. The barrel also repeats expansion and contraction due to pressure rise and fall in the pressure chamber, but since the pressure groove is provided, the outer diameter of the sleeve also expands and contracts at the same time. It is possible to prevent a large change in the gap between the barrel and the sleeve, prevent foreign matter from being caught between the barrel and the sleeve, or prevent the plunger from being caught in the barrel, which also improves durability. Moreover, since the pressure groove is formed between the plunger body and the sleeve, it is possible to suppress the volume of the pressure groove to a necessary minimum, and as a result, it is possible to prevent a decrease in the volumetric efficiency of the pump.

Further, in the fuel injection pump according to the second aspect, it is possible to prevent abnormal wear inside the barrel, so that the durability of the pump can be further improved.

[Brief description of drawings]

FIG. 1 is a central longitudinal sectional view showing an essential part of an embodiment of a fuel injection pump of the present invention, and FIG. 2 is a central longitudinal sectional view of a conventional example. 1 ... Barrel, 2 ... Plunger, 6 ... Sleeve, 9
...... Lead part, 12 …… TiN coating layer (cured part).

Front page continued (72) Creator Tatsuo Fujii 3-1-1 Higashikawasaki-cho, Chuo-ku, Kobe-shi, Hyogo Kawasaki Heavy Industries Ltd. Kobe factory (56) References Sho 49-63320 (JP, U) Actual opening Sho 60-28269 (JP, U) Actual opening Sho 62-71369 (JP, U)

Claims (2)

(57) [Scope of utility model registration request] 1. A fuel injection pump for ejecting fuel by reciprocally driving a plunger in a barrel, wherein the plunger comprises a plunger body and a tubular self-fluxing alloy sleeve fitted to a tip portion of the plunger body. And consists of
A lead portion is formed on the outer peripheral portion of the sleeve, and a relief portion whose outer peripheral portion is smaller in diameter toward the front end is provided at the tip end portion of the sleeve, while between the plunger body and the sleeve, A fuel injection pump characterized in that a pressure groove that opens into a pressure chamber on the tip side is provided around the pressure groove. 2. The fuel injection pump according to claim 1, wherein a hardened portion such as a TiN coating layer and a beam quenching portion is formed on the lead sliding contact portion on the inner peripheral portion of the barrel.