JP3319214B2 - Bearing structure of pump shaft in engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing structure for a pump shaft in an engine.

[0002]

2. Description of the Related Art Engines mounted on vehicles such as motorcycles, snowmobiles, and the like are provided with various pumps for pumping lubricating oil and cooling water to various parts of the engine. Driven by shaft power.

FIG. 6 shows a bearing structure of a conventional pump shaft.
This pump shaft a has a water pump b at one shaft end.
And an oil pump (not shown) at the other shaft end, and simultaneously drives the water pump b and the oil pump. In the bearing structure on the side of the water pump b, the bush d is inserted into the crankcase c, the pump shaft a is inserted through the bush d, and the oil seal e is assembled outside the bush d. The inside is sealed.

[0004]

By the way, when the pump shaft a reciprocates in the direction of the arrow g during rotation due to the rotation fluctuation of the crankshaft f, the flange a1 of the pump shaft a adjacent to the bush d and the bush d. Between the pumping action. Normally, since an oil film is formed between the bush d and the pump shaft a, the pressure in the substantially closed space h may increase due to the pump action, and the durability of the oil seal e may be extended. Will also be affected.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has been made to surely prevent a pressure increase in a gap between an oil seal and a bush, thereby improving the durability of the oil seal. An object of the present invention is to provide a bearing structure of a pump shaft in an engine.

[0006]

The present invention has the following configuration to achieve the above object. That is, the invention according to claim 1 is a bearing structure for rotatably supporting a pump shaft driven by a crankshaft on a crankcase. The bearing structure is inserted into the crankshaft and crosses the crankshaft.
A bush that axially supports the pump shaft extending to the outside, and an oil seal fitted to the pump shaft closer to the shaft end than the bush, and a gap is formed around the pump shaft between the oil seal and the bush. In the bearing structure of the pump shaft in the engine, the crankcase is provided with a gear chamber in which the drive gear of the crankshaft meshes with the driven gear of the pump shaft, and a bypass hole communicating the gap . With the pump shaft,
A water pump is provided at one shaft end and the other
The oil pump is provided at a shaft end, and the pump shaft
The bearing that supports the shaft end on the oil pump side of
A pump shaft bearing structure for an engine, wherein a through hole communicating with the gear chamber is provided .

According to a second aspect of the present invention, the oil pump side
The bearing structure is larger than the driven gear of the pump shaft.
A shaft hole having an inner diameter provided in the crankcase, and the shaft hole;
And a retainer inserted as said bearing portion.
A bearing structure of the pump shaft in the engine according to claim 1, wherein the that.

[0008]

According to the present invention, even if the pump shaft reciprocates during rotation due to the rotation fluctuation of the crankshaft and a pump action occurs, the pressure in the gap can be released to the gear chamber by the bypass hole. it can. Therefore, the pressure in the gap is set to the same pressure as that of the gear chamber, the rise in the pressure in the gap can be reliably prevented, and the durability of the oil seal can be increased.

In general, a water pump has a larger discharge rate and a larger load applied to a pump shaft than an oil pump. However, according to the present invention, even when the pump shaft has an oil pump and a water pump at both shaft ends, Since the water pump side of the pump shaft is supported by the bush having a large load resistance, the pump shaft can be stably supported. In this case, also on the oil pump side, a pressure increase can be prevented by the through hole provided in the bearing portion.

Further, by providing the bearing structure on the oil pump side with a retainer, the bearing structure on the water pump side can be configured to be supported by a bush. That is, the pump shaft is inserted from a shaft hole having an inner diameter larger than the outer diameter of the driven gear, the shaft end on the water pump side is stably supported by the bush, and the shaft end on the oil pump side to which a small load is applied. Can be supported by the retainer, and the pump shaft can be supported reasonably.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. The engine E according to the present embodiment is shown in FIGS.
As shown in FIG. 1, a two-cylinder engine mounted on a snowmobile, for example, has a vertically split crankcase 6.
And a cylinder 28 mounted and fixed on the upper crankcase 6a, and a cylinder head 30 fastened to the upper end of the cylinder 28. As shown in FIG. 3, a transmission means (drive gear 2) such as a screw gear or a worm gear is attached to the lower crankcase 6 b as shown in FIG.
a, a driven pump shaft 4 is rotatably supported via a driven gear 4a). This pump shaft 4 extends back and forth with respect to the crankshaft 2 extending left and right,
A water pump 18 is provided at one shaft end (right side in FIG. 3) and the other shaft end (left side in FIG. 3).
An oil pump 20 is provided.

As shown in FIG. 3, the water pump 18 has an impeller 34 fastened to a shaft end face of the pump shaft 4 with a bolt 32, and a screw 36 ( 2) (see FIG. 2). The water pump 18 draws cooling water from the inlet 38 a provided in the cover 38 into the center of the impeller 34, and sends the cooling water to the discharge port 46 inside the cover 38 by rotation of the impeller 34. .

As shown in FIG. 3, the bearing structure on the water pump 18 side is a bush 8 inserted from the inside into the wall of the crankcase 6b to support the pump shaft 4, and is closer to the shaft end than the bush 8. And an oil seal 10 fitted to the pump shaft 4 from the outside and inserted into the wall of the crankcase 6b from outside.
And a substantially annular space 12 is formed around the pump shaft 4 between the oil seal 10 and the bush 8. Note that a mechanical seal 48 is provided outside the oil seal 10.

As shown in FIGS. 3 and 4, the drive gear 2 of the crankshaft 2 is provided in the crankcase 6b.
A gear hole 14 in which a and a driven gear 4 a integrally formed with the pump shaft 4 mesh with each other, and a bypass hole 16 communicating the gap 12 are provided.

On the other hand, as shown in FIG. 3, the oil pump 20 is fastened to the outer wall of the crankcase 6b by a screw member 40, and operates by engaging with the shaft end of the pump shaft 4. The oil pump 20 and the gear chamber 14 communicate with each other via an external hose 42. The bearing structure on the oil pump 20 side is
A shaft hole 24 provided in the crankcase 6b having an inner diameter into which the driven gear 4a having an outer diameter larger than the pump shaft 4 can be inserted.
And a retainer 26 inserted as a bearing into the shaft hole 24.
And

As shown in FIGS. 3 and 5, the retainer 26 is fastened together with the oil pump 20 by the screw member 40. A through hole 22 is formed in each of the surface and the outer peripheral surface exposed in the gear chamber 14. The through holes 22 are provided in a pair at the distal end of the retainer 26 facing the gear chamber 14 so as to face each other in the radial direction.

According to the present embodiment having the above-described configuration, the pump shaft 4 reciprocates during rotation due to the rotation fluctuation of the crankshaft 2, and the pumping action is performed between the flange portion 44 a and the bush 8. Even if it occurs, the pressure in the gap 12 can be released to the gear chamber 14 by the bypass hole 16.
Therefore, the pressure in the gap 12 is set to the same pressure as the gear chamber 14, and the pressure in the gap 12 can be reliably prevented from rising. Therefore, the durability of the oil seal 10 can be improved.

In general, the water pump 18 has a larger discharge rate and a larger load applied to the pump shaft 4 than the oil pump 20, but in this embodiment, the water pump 18 side of the pump shaft 4 has a bush having a large withstand load. 8, the pump shaft 4 can be stably supported. Also, on the oil pump 20 side, even if a pumping action occurs between the flange portion 44b and the retainer 26, the through-hole 22 can prevent the pressure inside the retainer 26 from increasing.

Further, since the bearing structure on the oil pump 20 side is constituted by the retainer 26, the water pump 18
The shaft end on the side can be supported by a bush 8 having a large load resistance. That is, when assembling the pump shaft 4 having the driven gear 4a into the crankcase 6b, the shaft hole 2 having an inner diameter larger than the outer diameter of the driven gear 4a is used.
4, the shaft end of the water pump 18 side is stably supported on the bush 8, and the retainer 26 is inserted into the shaft hole 24 so that the load applied to the oil pump 20 is low. Is supported by a retainer 26 having a small load-bearing capacity, whereby the pump shaft 4 can be supported rationally.

This embodiment is a preferred embodiment of the present invention, and the technical scope of the present invention is not limited to this embodiment.

[0021]

As described above, according to the present invention, in a bearing structure of a pump shaft in an engine, a pressure increase in a gap between an oil seal and a bush can be reliably prevented. The durability of the seal can be improved.

[Brief description of the drawings]

FIG. 1 is a rear view of an engine according to an embodiment viewed from an air supply side.

FIG. 2 is a front view of the engine according to the embodiment as viewed from the exhaust side.

FIG. 3 is a sectional view taken along the line III-III in FIG.

FIG. 4 is an enlarged view of a portion A in FIG. 3;

FIG. 5 is an enlarged view of a portion B in FIG. 3;

FIG. 6 is an enlarged sectional view showing a conventional bearing structure.

[Explanation of symbols]

 2 Crankshaft 2a Drive gear 4 Pump shaft 4a Driven gear 6 Crankcase 8 Bush 10 Oil seal 12 Air gap 14 Gear chamber 16 Bypass hole 18 Water pump 20 Oil pump 22 Through hole 24 Shaft hole 26 Retainer E Engine

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-191236 (JP, U) JP-A-3-129708 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F01M 1/06 F01M 1/02 F01P 5/12 F02B 67/00

Claims (2)

(57) [Claims] 1. A bearing structure for rotatably supporting a pump shaft driven by a crankshaft on a crankcase, wherein the pump shaft is inserted into the crankshaft and is displaced from the crankshaft.
A bush that axially supports the pump shaft extending to the outside, and an oil seal fitted to the pump shaft closer to the shaft end than the bush, and a gap is formed around the pump shaft between the oil seal and the bush. is, in the bearing structure of the pump shaft in the engine, the said crankcase, a gear chamber in which the drive gear of the crankshaft and the driven gear of the pump shaft is engaged, and the bypass hole is provided for communicating the gap
And the pump shaft has a water pump at one shaft end.
And the oil pump is provided at the other shaft end.
Ri, supports the shaft end portion of the oil pump side of the pump shaft
The bearing portion has a through hole communicating with the gear chamber.
Bearing structure of the pump shaft in the engine, characterized in that that. 2. The bearing structure on the oil pump side comprises:
The inner diameter of the clamp is larger than the driven gear of the pump shaft.
A shaft hole provided in the case, and the shaft hole serves as the bearing.
The bearing structure for a pump shaft in an engine according to claim 1 , further comprising a retainer inserted and fitted .