JPH0424128Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to the structure of a timing belt cover for a DOHC engine.

(Prior art) Normally, in a DOHC engine, two camshafts are arranged in the cylinder head at the top of the engine, and a cam pulley is fixed to one end of the camshaft to drive the camshaft. A timing belt is installed between the engine and the engine so that it rotates in synchronization with the crankshaft. The timing belt cover that covers the timing belt has a shape that is wide in the upper part that covers the cam pulley and narrows as it reaches the crankshaft in the lower part (for example,
(See No. 134629).

However, in the timing belt cover of a DOHC engine as described above, the timing belt cover cannot be attached or detached unless it is removed from the front of the engine, which complicates engine maintenance work. In other words, when the timing belt cover is divided into two or three parts vertically, the uppermost timing belt cover is narrower at the bottom than at the top, and the sealing surface is installed at a lower position than the cam pulley. There is. Since various auxiliary equipment are installed on the front side of the engine, even if the bolts that secure the timing belt cover are removed, the auxiliary equipment must be removed and the timing belt cover moved forward. Otherwise, the flange-like portions forming the side sealing surfaces would interfere with the cam pulley and would not be able to be removed. Therefore, attaching and detaching the timing belt cover requires attaching and detaching auxiliary equipment, which makes the work when performing engine maintenance etc. complicated.

(Purpose of the invention) In view of the above circumstances, this invention allows the timing belt cover to be installed and removed without removing other parts.
The purpose is to provide a timing belt cover structure for a DOHC engine.

(Structure of the invention) The timing belt cover structure of the invention moves the timing belt cover, which tightly covers the front side of the cam pulley and the sides of the timing belt with the sealing surface on the outer periphery, in the attachment/detachment direction on the opposite side of the crank pulley. The sealing surface of one side of the timing belt cover that passes through the front side of the cam pulley during movement in the above-described attachment/detachment direction is set at a height near the front end face of the cam pulley;
This is characterized in that the height of the sealing surface on the other side that does not pass through the front side of the cam pulley is set at a height near the rear end surface of the cam pulley.

(Effect of the invention) According to the invention, when the timing belt cover moves in the attachment/detachment direction on the opposite side of the crank pulley, the height of the sealing surface on one side that passes through the front side of the cam pulley is set near the front end face of the cam pulley. By providing the seal surface at a height of The timing belt cover can be attached and detached without removing other parts such as auxiliary equipment, which improves work efficiency during maintenance.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.
FIG. 1 is a front view of the DOHC engine with the timing belt cover attached, and FIG. 2 is a front view of the DOHC engine with the timing belt cover removed.

The DOHC engine 1 has two camshafts 3 and 4 disposed on the left and right in the cylinder head at the top of the engine body 2. One end of each camshaft 3 and 4 protrudes toward the front side of the engine body 2. Cam pulleys 5 and 6 are attached to each. A timing belt 9 is placed between the cam pulleys 5 and 6 and a crank pulley 8 fixed to one end of the crankshaft 7, so that the camshafts 3 and 4 are driven to rotate in synchronization with the rotation of the crankshaft 7. . Above cam pulleys 5 and 6
A tension pulley 10 and an idler pulley 11 contact the timing belt 9 between the auxiliary drive pulley 1 and the crankshaft 7 from the outside.
2 are engaged from the inside.

Then, the front side of each pulley such as the cam pulleys 5, 6 and crank pulley 8, and the timing belt 9
A timing belt cover 15 is provided to cover the outer circumference of the engine, and outer seal surfaces 15a and 15b of the timing belt cover 15 are in contact with outer seal surfaces 16a and 16b of a back plate 16 attached to the engine body 2. It is attached to the engine body 2 with attachment bolts 17 on the outer periphery. The timing belt cover 15 and back plate 16 are divided into three parts: an upper part, a middle part, and a lower part.

The upper timing belt cover 15 is moved diagonally upward in the attachment/detachment direction A on the opposite side of the crank pulley 8 for attachment/detachment. As shown in FIG. 3, the sealing surface 15a on one side (left side in the figure) that passes through the front side of the
A sealing surface 15b on the other side (right side in the figure) that is formed low (short) at a height near 6a and does not pass through the front side of the cam pulleys 5 and 6 during movement in the attachment/detachment direction A.
is formed high (long) at a height near the rear end surfaces of the cam pulleys 5 and 6 on the engine main body 2 side.

On the other hand, the upper back plate 16 on the side of the engine body 2 is formed at a height corresponding to the shape of the sealing surfaces 15a, 15b of the timing belt cover 15. That is, the sealing surface 16a on one side (left side in the figure) is the front end surface 5 of the cam pulleys 5, 6.
The sealing surface 16b on the other side (right side in the figure) is formed low on the engine body 2 side near the rear end surface of the cam pulleys 5, 6, and the timing belt cover 15 is formed high on the front side near the timing belt cover 15.
The front surface of the timing belt cover 15 is parallel to the front end surfaces 5a, 6a of the cam pulleys 5, 6 when it comes into contact with the seal surfaces 15a, 15b of the timing belt cover 15.

With the above structure, the timing belt cover 15 can be attached and detached by moving obliquely upward in the attachment/detachment direction A without making a large movement in the front-rear direction. That is, when removing the timing belt cover 15, the mounting bolts 17 are removed and then the timing belt cover 15 is moved in the above-described attachment/detachment direction A. In moving in this direction A, the timing belt cover 15 is removed. The lower sealing surfaces 15a of the cam pulleys 5 and 6 are moved so as to pass through the end surfaces of the cam pulleys 5 and 6 without interfering with them, and are extracted upwardly. When attaching the timing belt cover 15 to the engine body 2, similarly move the front side of the timing belt cover 15 from the above direction A so that the sealing surface 15a does not interfere with the cam pulleys 5 and 6, and install it in the predetermined attachment position. and then tighten the mounting bolts 17 to fix it. Therefore, the timing belt cover 15 can be attached and detached without removing various auxiliary equipment installed on the front side of the engine body 2.

Note that the direction in which the timing belt cover 15 is attached and detached, that is, the side that forms the lower sealing surface 15a of the timing belt cover 15 is the engine body 2.
It is set in accordance with the installation of surrounding auxiliary equipment, etc., and the sealing surface of the part that passes through the front side of the cam pulleys 5, 6 and interferes with the cam pulleys 5, 6 is low in accordance with the direction. It is something that is formed.

The height of the sealing surface 15a of the timing belt cover 15, which is formed low, is preferably formed forward of the front end surfaces 5a, 6a of the cam pulleys 5, 6.
The front end surface 5 within the forward movable range of 5.
It can be formed high near a and 6a.

[Brief explanation of the drawing]

Figure 1 is a front view of a DOHC engine with a timing belt cover installed, according to an embodiment of the present invention, Figure 2 is a front view of the DOHC engine with the timing belt cover removed, and Figure 3 is a front view of a DOHC engine with a timing belt cover removed. FIG. 3 is a cross-sectional view showing the shapes of the timing belt cover and back plate taken along the - line in the figure. 1...DOHC engine, 2...engine body,
3, 4...Camshaft, 5, 6...Cam pulley, 5a, 6a...Front end surface, 9...Timing belt, 15...Timing belt cover, 15
a, 15b...Sealing surface, 16...Back plate, 16a, 16b...Sealing surface, 17...Mounting bolt, A...Detachment direction.

Claims (1)

[Scope of utility model registration request] A timing belt cover that tightly covers the front side of the cam pulley installed on the two camshafts arranged in the cylinder head and the side of the timing belt that engages with the cam pulley with a sealing surface on the outer periphery is installed on the opposite side of the crank pulley. This is a timing belt cover structure for a DOHC engine that is attached and detached by moving in the side attachment/detachment direction, and the height of the sealing surface on one side of the timing belt cover that passes the front side of the cam pulley when moving in the attachment/detachment direction is higher than the cam pulley. The sealing surface of the DOHC engine is provided at a height near the front end surface of the cam pulley, while the height of the sealing surface on the other side that does not pass through the front side of the cam pulley is provided at a height near the rear end surface of the cam pulley. Timing belt cover structure.