JPH0261637B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mounting structure for an engine oil pump, and in particular, to a mounting structure for an engine oil pump, and in particular to a mounting structure for an engine oil pump that is mounted inside the engine case body and driven directly by the shaft end of a camshaft. Regarding the installation structure of the oil pump.

[Conventional technology]

In engines where the camshaft is placed inside the engine case body, such as a side valve type 4-stroke engine, lubricating oil (oil) stored at the bottom of the case body is pumped to the main bearing of the crankshaft. As a means, an oil pump directly driven by the shaft end of the camshaft may be used.

The conventional structure of this type of oil pump (lubricating oil pump) is
54119) and Utility Model Application No. 167210 (1987-167210)
- No. 54216).

First, the structure of these conventional oil pumps for vertical shaft type engines will be explained with reference to FIG.

In FIG. 1, a crankshaft 2 and a camshaft 3 are supported in a case body 1 of an engine in parallel with each other with their axes oriented vertically.

The bottom of the case body 1 is integrally formed with a bearing boss 4 for bearing the lower end of the camshaft 3 and a recess 5 that opens outward at a concentric position below the bearing boss. This recess 5 forms a pump chamber, and after inserting a pump rotor 6, the pump rotor is held by fastening a cover 8 to the outer surface of the case body with bolts 7.

The pump shaft 9 is supported in a through hole formed in a partition wall between the bearing boss 4 and the recess 5, and its tip engages with the shaft end of the camshaft 3. Furthermore, an oil inlet 10 for the pump is formed at the back of the recess 5, that is, at the upper end.

The discharge port 11 of the pump communicates from the pump chamber 5 to the inside of the bearing boss 4, and oil is fed upward through an oil guide hole 12 formed in the camshaft 3, and then supplied to the crank main bearing 13, etc. .

Around the bearing boss, a wall-shaped projection (a wall having an oil communication hole may be used) 14 for defining a filtration chamber 15 is formed integrally with the case body 1,
The filter element 16 installed in the filtration chamber 15 is held by a filter holder 17 attached to the upper end of the wall-like projection 14. In addition,
Reference numeral 18 indicates the oil level.

The conventional oil pump structure described above with reference to FIG. 1 has the following problems.

(i) Since the structure is such that the pump rotor 6 is inserted into the recess 5 and then the cover is fastened to hold the pump rotor, oil leakage may occur at the cover mounting surface (gasket surface).

(ii) Since the cover 8 and the heads of the mounting bolts 7 protrude from the surface of the case body 1, the external dimensions of the engine become larger. Note that if the cover mounting surface is recessed so that this portion does not protrude, machining of the gasket surface will become difficult.

(iii) In the case of a vertical shaft type engine as shown in the figure, since the pump inlet 10 is formed at the upper part of the recess (pump chamber) 5, the range between the highest and lowest oil levels is reduced. The amount of oil that can be used effectively decreases.

[Purpose of the invention]

The purpose of the present invention is to solve these conventional problems and eliminate the possibility of oil leakage by removing the opening and the cover that blocks it by configuring it inside the case body of the engine, and also to eliminate the possibility of oil leakage on the surface of the case body. To provide a camshaft-driven oil pump whose appearance can be improved and made more compact by eliminating a protruding part, and which can also be simplified in structure by reducing the number of parts constituting a pump chamber. It is.

[Structure of the invention]

The present invention is characterized in that a bearing boss having a bearing hole that supports the end of the camshaft is formed as a separate member from the case body, a recess is formed in the inner surface of the case body, and the bearing boss has a flat surface. By directly fastening the bearing boss to the inner surface of the case body from the inside with the back surface in close contact with the open end surface of the recess, a sealed pump chamber that accommodates the pump rotor is formed, and the pump shaft of the pump rotor The above object is achieved by a structure in which the camshaft is pivotally supported from the pump chamber to the bearing hole side through the bearing boss and is engaged with the end of the camshaft.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 2 and 3.

In FIGS. 2 and 3, a camshaft 22 is rotatably supported within a case body 21 of the engine. The illustrated example shows the case of a vertical shaft type engine.

The lower end of the camshaft 22 is supported by a bearing boss 24 that is separate from the case body. This bearing boss 24 is fixed to the inside of the case body 21 by bolts 23. In the illustrated example, the bearing boss 24 is fixed in an accurately centered state by the spigot part.

A recess 26 is formed in a portion of the inner surface of the case body 21 that corresponds to the bearing boss 24 .

Therefore, by directly fastening the bearing boss 24 to the inner surface of the case body 21 from the inside with the flat back surface of the bearing boss 24 in close contact with the open end surface of the recess 26, the pump rotor 25 is housed in a sealed manner. A pump chamber is formed.

The case body 21 also serves as an oil reservoir, and oil is stored at the bottom up to a level 27.

Further, the case body 21 is formed with a pump suction port 28 and a pump discharge port 29 as shown in FIG.
It is supplied to the main bearing and big end of the crank through the pump. A relief valve 3 is located in the middle of the oil guide hole 30.
1 is provided so that the oil supply pressure can be adjusted.

A screen (or filter) 32 is arranged at a position surrounding the oil suction port 28, and the screen is held in a predetermined position by being pressed by a projecting portion 33 formed integrally with the bearing boss 24.

The shaft of the pump rotor 25, that is, the pump shaft 34
is supported by a bearing portion formed in the case body 21 and the bearing boss 24, and its upper end portion extends into the bearing boss 24 and engages with the end of the camshaft shaft so that rotational force can be transmitted.

Note that as the oil pump, in addition to a rotary pump having a pump rotor 25 such as a trochoid pump, a pump having a rotary pumping body corresponding to the rotor such as a gear pump can be used.

The camshaft 22 is provided with a driven gear 35 for receiving rotation of the crankshaft, and cam portions 40 and 41 that abut against tappets 38 and 39 of an intake valve 36 and an exhaust valve 37, respectively.

According to the embodiment described above with reference to FIGS. 2 and 3, the oil pump is all constructed inside the case body, so the cover (cover 8 in FIG. 1) in the conventional structure can be removed. , eliminating the possibility of oil leakage. at the same time,
Since parts such as the cover and cover mounting bolts that protrude from the surface of the case body are eliminated, the external dimensions of the engine can be reduced.

Further, since the pump chamber is formed simply by forming the recess 26 on the inner surface of the case body 21 and directly joining the back surface (flat surface) of the bearing boss 24 to the open end surface of the recess and sealing it, the pump rotor 2
It is possible to maintain stable pump function by eliminating the accumulation of tolerances in the gap (side clearance) between the side surface of 5 and the side surface of the pump chamber, and to simplify the pump structure by reducing the number of parts. can.

Further, since all the processing of the case body 21 can be performed from the inside, the processing is easy, and the centering of the camshaft bearing portion and the pump is also easy.

Furthermore, since the bearing boss 24 also serves as a screen presser, it is possible to reduce the number of parts.

Furthermore, in the case of a vertical shaft type engine as shown in the figure, the position of the pump suction port 28 can be lowered compared to the conventional structure, so the difference between the upper and lower limits of the oil level 27 can be increased, allowing for effective utilization. The effect of increasing the amount of oil produced can also be obtained.

Although the above embodiments show the case where the present invention is applied to a vertical shaft type engine, the present invention can be similarly applied to a horizontal shaft type engine or a tilted shaft type engine.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, in an engine oil pump that is directly driven by the shaft end of a camshaft provided in the engine case body, a bearing hole that supports the end of the camshaft is provided. A bearing boss is formed of a member separate from the case body, and a recess is formed on the inner surface of the case body, and the bearing boss is inserted with the flat back surface of the bearing boss in close contact with the open end surface of the recess. By directly fastening to the inner surface of the case body from the inside, a sealed pump chamber housing the pump rotor is formed, and the pump shaft of the pump rotor passes through the bearing boss from the pump chamber to the bearing hole side. Since it is configured to be pivotally supported and engaged with the end of the camshaft, it is possible to eliminate the possibility of oil leakage and to simplify the pump structure. An engine oil pump is provided that can eliminate objects.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view illustrating a conventional engine oil pump, FIG. 2 is a vertical sectional view illustrating an embodiment of the engine oil pump according to the present invention, and FIG. 3 is a separate view of the oil pump shown in FIG. 2. FIG. 21...Case body, 22...Camshaft, 24...
... Bearing boss (camshaft), 25 ... Pump rotor,
26... recess (pump chamber), 27... oil level, 34... pump shaft.

Claims (1)

[Claims] 1. In an engine oil pump that is directly driven by the shaft end of a camshaft 22 provided in the case body 21 of the engine, a bearing boss 24 having a bearing hole that supports the end of the camshaft 22 is connected to the case body 2.
The case body 21 is formed of a separate member from the case body 21.
By forming a recess 26 on the inner surface of the case body 21 and directly fastening the bearing boss 24 to the inner surface of the case body 21 from the inside with the flat back surface of the bearing boss 24 in close contact with the open end surface of the recess 26, A sealed pump chamber that accommodates the pump rotor 25 is formed, and the pump shaft 3 of the pump rotor 25 is
4 is pivotally supported from the pump chamber to the bearing hole side through the bearing boss 24 and is engaged with an end of the camshaft 22.