JPH018665Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an improvement in the timing belt cover structure of an engine.

(Prior art) The camshaft that opens and closes the intake and exhaust valves in synchronization with engine rotation is often driven by the crankshaft via a timing belt. A timing belt is wound between the timing pulley and the provided timing pulley. In order to prevent foreign matter such as water droplets and dust from adhering to the timing belt and to always maintain a synchronized relationship between the crankshaft and camshaft (intake/exhaust valves), Japanese Utility Model Application No. 53-145013 As shown, the timing belt is covered with a timing belt cover. This timing belt cover is attached to the engine body with bolts, but in order to more reliably prevent foreign matter from entering the timing belt cover, a sealing member is interposed around the periphery of the timing belt cover. The timing belt cover is designed to be bolted together with the timing belt cover extended to the vicinity of the crankshaft.

By the way, in addition to the above-mentioned timing pulley, a V-belt pulley is attached to the crankshaft in order to drive auxiliary equipment such as an alternator and a cooling fan, but this V-belt pulley usually has a larger diameter than the timing pulley. , and is installed outside the timing pulley. Therefore, without being hindered by this V-belt pulley,
When you try to tighten or loosen the timing belt cover mounting bolt, the bolt tightening position (the bolt fixing position) is inevitably restricted.
The timing belt cover had to be located far away from the camshaft side than the crankshaft side end.

Therefore, the so-called overhang part of the timing belt cover, that is, the part closer to the crankshaft than the bolt fastening position, warps due to the reaction force of the seal member due to the bolt fastening force, and the timing belt cover is lifted off the engine body. As a result, a problem has arisen in that the sealing performance of the sealing member is not ensured as desired.

(Purpose of the invention) The present invention has been made in consideration of the above circumstances, and is intended to prevent the timing belt cover (the overhang part) from warping due to the bolt fastening force, and to ensure the sealing performance of the sealing member. An object of the present invention is to provide a timing belt cover structure for an engine that can secure the timing belt cover structure.

(Structure of the invention) In order to achieve the above-mentioned object, in the present invention, the rigidity in the bolt fastening direction of the seal member provided on the peripheral edge of the timing belt cover is set to be higher than the camshaft side part with the bolt fastening position as the boundary. The crankshaft side part is also lower.

(Embodiment) In FIG. 1, 1 is a crankshaft, and 2 is a camshaft. Both shafts 1 and 2 are each rotatably held in an engine body A (see FIG. 2). Crankshaft 1 has pin 3
A timing pulley 5 is fixed to the camshaft 2 by bolts 4, and a timing pulley 7 is fixed to the camshaft 2 by bolts 6.

A pump timing pulley 8 and an idler pulley 9 are disposed approximately midway between the shafts 1 and 2, and a timing belt 10 is wound around each of the pulleys 5, 7, 8, and 9. As a result, the camshaft 2 is driven to rotate in synchronization with the rotation of the crankshaft 1, and the intake and exhaust valves (not shown) are opened and closed at predetermined timing. The timing pulley 8 is fixed to a rotating shaft 11 of, for example, a fuel injection pump held in the engine body A by bolts 12.

As shown in FIG. 2, a V-belt pulley 13 is further fixed to the crankshaft 1 on the outside of the timing pulley 5. This V-belt pulley 13 is for driving auxiliary equipment such as an alternator and a cooling fan (not shown), and has a larger diameter than the timing pulley 5.
V belt 1 wound around this V belt pulley 13
4 is wound around, for example, a V-belt pulley 15 for an alternator and a V-belt pulley 16 for a cooling fan.

The timing belt 10 is covered by a timing belt cover 17, and in the embodiment, the timing belt cover 17 is covered with an upper cover 1.
8 and a lower cover 19.
This upper cover 18 is fixed to the engine body A by bolts 20 at four attachment parts 18a provided on its periphery, and the lower cover 19 is fixed to the engine body A at three attachment parts 19a provided on its periphery. bolt 21
(21A, 21B, 21C) are fixed to the engine body A.

Both covers 18 and 19 are generally box-shaped, each having a surface portion and a side wall portion, as in the conventional case, but the upper cover 18 is opened only at its lower portion, and the entire portion of the timing pulley 7 is opened. The lower cover 19 is designed to cover approximately the upper half of the timing pulley 8, and the lower cover 19 is opened at both the upper and lower portions so as to cover approximately the lower half of the timing pulley 8. Of course, both covers 18 and 19 can be assembled to each other without any gaps, for example by stacking their end portions one above the other, as shown in FIG. Both covers 18 and 19 are arranged as shown by broken lines in FIG.
Seal members 22 (for the upper cover 18) and 23 (for the lower cover 19) made of an elastic material are integrated into the peripheral portion of the engine body A by fitting, for example.
It is designed to create a seal between the

The lower end of the lower cover 19, that is, the end on the crankshaft 1 side, extends to the vicinity of the crankshaft 1, and a bolt 21 provided on one side wall of the lower cover 19 extends to the vicinity of the crankshaft 1.
A, and the bolt 21 provided on the other side wall
B is located slightly outside the outer periphery of the V-belt pulley 13 in the radial direction. As a result, V
Bolt 21C far away from belt pulley 13
Of course, the bolts 21A and 21B can also be approached from the axial direction of the crankshaft 1 without being obstructed by the V-belt pulley 13.

Bolts 21 to the lower cover 19 as described above
Due to the arrangement of bolts 21A and 21B, the portion of the lower cover 19 on the lower side in FIG. 1 (the portion on the crankshaft 1 side) is a so-called overhang portion B. The rigidity of the seal member 23 in the fastening direction by the bolts 21A and 21B is lower at the overhang portion B than at other portions. That is, the sealing member 23 in the overhang part B has a narrow protrusion 23a as shown in FIG. 6, while the sealing member 23 in other parts has the protrusion 23a as shown in FIG. 23a is not formed. Thereby, the sealing member 23 in the overhang portion B is more easily bent and deformed than the sealing member 23 in other portions shown in FIG. 5 due to the action of the protruding portion 23a.

Note that the height (length in the bolt fastening direction) of the seal member 23 is the same in both FIGS. 5 and 6.

Therefore, as shown in FIG. 8, when the bolt fastening force P is applied to the seal member 23, the overhang portion B does not warp upward from the engine body A, and the lower cover 19 and the engine body The sealing performance between A and A is ensured. To explain this point in detail, if the rigidity of the seal member 23 at the overhang part B is the same as that of other parts, when the bolt fastening force P is applied, as shown in FIG. As a fulcrum, by the reaction force of the seal member 23,
The free end of the overhang portion B (end on the side of the crankshaft 1) is warped so as to be lifted from the engine body A (the amount of this lifting is shown by δ in FIG. 7). However, by adjusting the rigidity of the sealing member 23 as in the present invention, the sealing member 23 is bent and deformed before the reaction force that causes the warping becomes large, and in other words, the sealing member 23 is lifted up due to the warping. The sealing member 23 at the overhang portion B is bent and deformed to compensate for the amount.
This prevents a gap δ from forming between the engine body A and the engine body A.

In the embodiment, the lower open end of the lower cover 19 is aligned with a receiving cover 24 attached to the engine body and surrounding the lower part of the timing pulley 8. Furthermore, the mounting surface of the engine body A to which the timing belt cover 17 is mounted does not necessarily have to be the same surface; for example, a pump mounting bracket or the like may be interposed so that the sealing member 23 is partially attached to the bracket. It may be configured such that it is in close contact with.

(Effects of the invention) As is clear from the above, the invention has the following effects:
The timing belt cover is prevented from warping when bolts are tightened, and the sealing member reliably seals between the timing cover and the engine body. As a result, foreign objects are prevented from entering the timing belt cover. This can be reliably prevented. Further, since it is only necessary to adjust the rigidity of the sealing member, it can be implemented easily and inexpensively.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional front view showing an embodiment of the present invention. FIG. 2 is a simplified side sectional view of FIG. 1. FIG. 3 is a plan view of the lower cover constituting the timing belt cover. FIG. 4 is a sectional view taken along the line -- in FIG. 3. FIG. 5 is a sectional view taken along the line shown in FIG. 3. Figure 6 is Figure 3-
Line sectional view. 7 and 8 are sectional views taken along the longitudinal direction of the sealing member. FIG. 7 shows a case where the timing belt cover is warped, and FIG. 8 shows a case according to the present invention. A: Engine body, B: Overhang part, 1:
Crankshaft, 2: Camshaft, 5, 7:
Timing pulley, 10: Timing belt, 1
7: Timing belt cover, 19: Lower cover,
21: Bolt, 23: Seal member, 23a: Projection.

Claims (1)

[Scope of claim for utility model registration] A timing belt is wound between a timing pulley provided on the crankshaft and a timing pulley provided on a camshaft, and a timing belt cover is provided to cover the timing belt, and a sealing member is interposed on the periphery of the timing belt cover. In the engine timing belt cover mounting structure, which is attached to the engine body with bolts, the crankshaft side end of the timing belt cover extends to the vicinity of the crankshaft, and the timing belt cover is attached to the engine body by bolts. The seal member is bolted at a position a predetermined distance away from the crankshaft side end, and the rigidity of the seal member in the bolt fastening direction is lower than that of the crankshaft side end compared to the camshaft side end at the bolt fastening position which is the predetermined distance away. The engine timing belt cover structure is characterized by being lower.