JPS63246482A - Oil pump - Google Patents

Abstract

PURPOSE:To circulate leaked lubricating oil to a suction room so as to improve pumping efficiency by dually providing the pump room side and the outer side with a seal being formed by the cover-attaching face of a casing and the inner face of the cover being in close contact with each other. CONSTITUTION:An oil pump 1 for an internal combustion engine has a pump casing 5 and a cover 24 in close contact with the casing. The contact face between the casing 5 and the cover 24 allows a pump room to be sealed. A cover-attaching face 22 is dually formed so that it is separated into a pump room side portion 22a enclosing a circular recess 6 and the outer portion 22b. Leaked lubricating oil, instead of being allowed to return to an oil pan, is directly circulated to a suction room via a passage 26 that circulates lubricating oil under excessive pressure to the suction room 10. Hence, reduced channel resistance owing to a strainer and a piping results in decrease in a negative pressure within the suction room and leads to the improvement of pumping efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an oil pump for an internal combustion engine, and more particularly to an oil pump driven by the engine's crankshaft or camshaft.

<Prior Art> Generally, an oil pump for an internal combustion engine is driven by the engine's crankshaft or camshaft I, and pumps a required amount of lubricating oil to each part of the engine at a discharge pressure depending on the engine rotation speed. In particular, as disclosed in Japanese Unexamined Patent Publication No. 59-173584, a trochoidal (internal gear type) pump that pumps lubricating oil by changing the volume of the gap formed between an outer rotor and an inner rotor is compact. Because it can achieve high discharge pressure and high oil flow rate, it is widely used in automobile engines.

In this type of pump, the suction side of the pump chamber has a low negative pressure, but the discharge side has a considerably high pressure, so oil may leak from the gap between the pump casing and the cover near the discharge side. be.

Normally, leaked lubricating oil is returned to the oil pan as it is and then sucked into the pump chamber again via the strainer and conduit, which results in the inconvenience of wasted engine output and reduced pump efficiency.

<Problems to be Solved by the Invention> Therefore, an object of the present invention is to improve pump efficiency by guiding lubricating oil leaking from the discharge side of an oil pump directly to the suction side without returning it to the oil pan. Our goal is to provide a new oil pump.

<Means for Solving the Problems> According to the present invention, the above object includes a pump casing and a cover that is in close contact with the casing, and a pump chamber is sealed by the close contact surface of the casing and the cover. The oil pump is configured such that the close contact surface is
This is achieved by providing an oil pump characterized in that the oil pump is formed in double portions near the discharge side of the pump chamber, one on the side of the pump chamber and the other on the outside, with a passage communicating with the suction side of the pump chamber interposed therebetween.

<Operation> By doing so, most of the lubricating oil leaking from the discharge side of the pump chamber is directly circulated to the suction side without being returned to the oil pan.

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, an oil pump 1 to which the present invention is applied is a trochoid type pump, which is fixed to the front part of a cylinder block 2 of an engine and is directly driven by a crankshaft 3. An oil pan 4 is attached to the lower side of the oil pump 1 and the cylinder block 2, and lubricating oil stored therein is sucked in by the oil pump 1 and pumped to each part of the engine.

As shown in FIG. 2, a solar radiation recess 6 is provided at the center inside the pump casing 5 of the oil pump 1, and the crankshaft 3 is inserted slightly eccentrically from the circular recess 6. A through hole 7 is bored. Inside this circular recess 6, inner and outer rotors, which will be described later, are arranged,
The bottom surface 8 and inner circumferential surface 9 are machined to be smooth and precisely so as to be rotated by the crankshaft 3.

Two recesses 10.11 are provided in the bottom surface 8, diametrically opposite each other from the recess 6. One of the recesses 10 communicates with a lubricating oil intake port 13 opened at the lower end of the casing 5 through an inlet passage 12, and is a suction chamber for sucking lubricating oil from the oil pan 4 through a strainer and a pipe (not shown). is defined. The other recess 11 communicates with a lubricating oil discharge port 15 via a discharge passage 14, and forms a discharge chamber for pumping high-pressure lubricating oil to various parts of the engine.

The fourth part 10 has a concave part 1 in a direction opposite to the rotational direction A of the rotor.
Extend to near the middle position between 1 and 1? 116, and a groove 17 extending toward the recess 11 along the rotor rotation direction A. Furthermore, a relatively shallow step 18 is provided on the bottom surface 8.
Continuing from section 1-7, it is recessed to near the intermediate position with recess 11. On the other hand, the recess 11 is provided with a groove 19 extending symmetrically with the groove 16 in the rotor rotational direction A to a position near the intermediate position between the recess 10 and the recess 10 . A relatively shallow small groove 21 extending from the end 20 on the side of the recesses 1 and 1 is recessed in the bottom surface 8 in a direction opposite to the rotor rotational direction A.

A smooth surface 22 for attaching a cover is formed around the circular recess 6, and a plurality of bolt holes 23 for fastening the cover are bored at appropriate positions. Cover mounting surface 2
2 has a passage 26 extending from the vicinity of the discharge chamber 11 to the suction chamber 10.
is recessed.

The end of this passage 26 opens into the inlet passage 12, and the tip extends to the vicinity of the discharge chamber 11. As a result, the cover mounting surface 22 is divided into a pump chamber side portion 22a surrounding the circular recess 6 and an outer portion 22b, and is formed in a double layer. Further, a side hole 27a is opened in the passage 26 and is bored at an intermediate position of a relief passage 27 that opens into the discharge passage 14.

A well-known relief valve 28 is installed in the relief passage 27, and when the discharge pressure exceeds a certain level, excess pressure lubricating oil is discharged into the passage 26 through the side hole 27a and circulated to the suction chamber 10 side. It has become.

A smooth surface 30 is provided on the outside of the cover mounting surface 22 on the same plane as the cover mounting surface 22 via a recess 29 . A plurality of bolt holes 31 are drilled at appropriate positions in this surface 30, and the pump casing 5 is fastened to the cylinder block 2 from the outside with bolts.

As shown in FIG. 3, the circular recess 6 has an outer rotor 32.
and inner rotor 33 are mounted so as to rotate while meshing with each other, and cover 24 is fastened to cover mounting surface 22 with bolts 25. The inner surface of the cover 24 is formed to be smooth like the cover mounting surface 22, and the tightening force of the bolt 25 brings the two into close contact with each other, so that a seal is formed by the close contact surface. Also, cover 2
4 is formed with recesses corresponding to both recesses 10 and 11. As a result, hydraulic pressure acts on both the inner and outer rotors 32, 33 from both sides in the suction chamber 10 and the discharge chamber 11, so that the rotors 32 and 33 are balanced.

As clearly shown in FIG. 4, the inner surface 34 of the cover 24 is in close contact with the pump chamber side portion 22a and the outer portion 22b of the cover mounting surface 22 in the vicinity of the discharge chamber 11. In this way, a double seal is formed across the extended portion 26a of the passage 26.

Since this sealing surface is only pressed by the cover mounting surface 22 and the cover inner surface 34 by the tightening force of the bolt 25, when the oil pressure in the discharge chamber 11 becomes high, both surfaces 22
．． Lubricating oil leaks from the gap at 34. The lubricating oil leaked into the extension part 26a is caused by the oil pressure in the suction chamber 10, while the oil pressure in the discharge chamber 11 is a relatively high positive pressure (approximately 5.7 kg/CX1).
Since the oil pressure is a low negative pressure (approximately -0.2 stg/J), it is easily circulated through the passage 26 to the suction chamber 10.

In this way, when the inner and outer rotors 32.33 are driven by the crankshaft 3, lubricating oil is sucked into the suction chamber 10 from the oil pan 4 via the lubricating oil intake 13 and the inlet passage 12, and both rotors 32.33 The lubricating oil is pressurized by the lubricant and is pressurized at a desired discharge pressure from the discharge chamber 11 through the discharge passage 14 and the lubricating oil outlet 15 to each lubricated part of the engine.

<Effects of the Invention> As described above, according to the present invention, the seal formed by the cover mounting surface of the gauging and the inner surface of the cover, which are in close contact with each other, is formed between the pump chamber side and the outside in the vicinity of the discharge chamber. By circulating the lubricating oil directly to the suction chamber through the passage that circulates the overpressure lubricating oil to the suction chamber, without returning the leaked lubricating oil directly to the oil pan.
The flow path resistance due to the strainer and piping is reduced, the negative pressure in the suction chamber is reduced, and the pump efficiency is improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an oil pump to which the present invention is applied. FIG. 2 is a rear view showing the inside of the pump casing. FIG. 3 is a rear view of the pump casing without the cover attached. FIG. 4 is an enlarged sectional view taken along line IV--IV in FIG. 3. 1...Oil pump 2...Cylinder block 3
...Crankshaft 4...Oil pan 5...Pump casing 6
...Circular recess 7...Through hole 8...Bottom surface
9...Inner peripheral surface 10...Suction chamber 1
1...Discharge chamber 12...Inlet passage 13...Lubricating oil intake 14...Discharge passage 15...Lubricating oil outlet 16.17...Groove 18...Step 19
...Groove 20...End portion 21...Groove
22...Cover mounting surface 22a...Pump chamber side portion 22b...Outside portion 23...Bolt hole 24...Cover 25...
Bolt 26...Passage 26a...Extension part
27... Relief passage 27a... Side hole 2
8... Relief valve 29... Recess 30...
・Smooth surface 31...Bolt hole 32...Outer rotor 33...Inner rotor 34...Inner surface Patented
Applicant: Representative of Honda Motor Co., Ltd.
Patent Attorney Yo Oshima -2 Figure 1 Figure 3 Figure 4 Figure 2b

Claims (2)

[Claims] (1) An oil pump comprising a pump casing and a cover in close contact with the casing, the pump chamber being sealed by a close contact surface between the casing and the cover, wherein the close contact surface is the pump chamber. 1. An oil pump characterized in that the oil pump is formed in double portions on the pump chamber side and on the outside, with a passage communicating with the suction side in the vicinity of the discharge side of the oil pump. (2) The oil pump according to claim 1, wherein the passage communicates with a discharge pressure adjustment relief passage that communicates from the discharge side to the suction side of the pump chamber.