JPH0121244Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a mounting structure for a sheet metal cam timing belt pulley used primarily in automobile engines.

[Prior Art] Recently, sheet metal belt pulleys are often used as cam timing belt pulleys, but this type of pulley is inferior to conventional sintered metal pulleys in terms of rigidity, so camshaft belt pulleys are often used. Depending on how the timing belt is attached to the timing belt, the noise during rotation may be large, and the durability of the timing belt may be deteriorated due to swinging of the pitch circle.

Therefore, when attaching this type of pulley to a camshaft, conventionally the end of the camshaft was formed large, and the pulley was attached to this end by attaching multiple bolts equally spaced from each other on the circumference at a certain distance from the center of the pulley. This can be done by inserting the pulley through the pulley and fixing it directly to the camshaft with the bolt, or by placing a flat presser plate on the center of the pulley, as shown in the prior art in Japanese Utility Model Application Publication No. 58-72556. A bolt passing through the center of the presser plate and the pulley is used to press and fix the camshaft via the presser plate, and a protrusion provided on the camshaft is fitted into a positioning hole provided on the pulley side. There are some systems in which the pulley is positioned relative to the camshaft.

[Problems to be Solved by the Invention] However, the former method has disadvantages in that the number of processing steps and assembly steps increases, and the weight of the camshaft increases.

In addition, in the latter case, since there is only one bolt and the holding plate is flat, the tightening force from the bolt acts only near the center of the pulley, making it impossible to obtain sufficient tightening force. This may cause problems such as large noise during rotation and deterioration of the durability of the timing belt due to vibration of the pitch circle.

Furthermore, in this conventional example, the timing belt must be installed after the cam timing pulley is installed on the camshaft.
There was a problem in that it was difficult to rotate the pulley and it took time to assemble the belt.

The present invention aims to solve the above problems.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a cam timing belt pulley made of sheet metal on the end face of the camshaft of an engine, and connects the press plate and the cam timing belt via a press plate. In the timing belt pulley installation structure that is fixed with a single bolt that passes through the center of the pulley and is screwed to the axis of the camshaft, the holding plate is
A cup consisting of a cylindrical portion formed substantially perpendicular to a contact surface with the cam timing belt pulley and a tightening seat portion for the bolt, and which contacts the cam timing belt pulley only at the cylindrical portion. A knock pin, which passes through the cam timing belt pulley and positions the timing belt pulley with respect to the camshaft, is fixed to the cylindrical portion of the presser plate.

[Operation and Effect] With this configuration, the portion relatively distant from the center of the timing belt pulley can be tightened uniformly and firmly along the circumferential direction, thereby reducing noise when the pulley rotates. It is possible to prevent the timing belt from becoming large, and it is also possible to reliably prevent the durability of the timing belt from deteriorating due to vibration of the pitch circle.

Further, since there is no need to enlarge the end face of the camshaft, the weight of the camshaft does not increase, and it is possible to provide a mounting structure for a cam timing belt pulley made of sheet metal that is simple in structure and can be implemented at low cost.

Furthermore, since the dowel pin is fixed to the presser plate in advance, the timing belt can be easily attached as described later.

[Example] Hereinafter, an example of the present invention will be specifically described with reference to the drawings.

FIG. 1 is a sectional view showing the main parts of this embodiment. In the figure, reference numeral 1 indicates a cam timing belt pulley made of sheet metal, which is formed by punching a steel plate and forming it into a desired shape by pressing, etc. The cam timing belt pulley 1 has teeth 3 on its outer periphery with which the timing belt 2 meshes. There is. On the other hand, in the figure, numeral 4 is a camshaft protruding from a partition wall 5a in a cylinder head 5 of the engine, and numeral 6 is an oil seal that maintains fluid tightness between the camshaft 4 and the partition wall 5a. The cam timing belt pulley 1 is mounted on the protruding end surface of the camshaft 4.

More specifically, the annular fitting protrusion 9 protruding from the center of the end face of the camshaft 4 is accurately fitted into the axial hole 8 of the cam timing belt pulley 1, and the fitting protrusion 9 is fitted onto the cam timing belt pulley 1 side with high accuracy. The provided positioning notch 10 is aligned with the fitting hole 22 provided on the end face of the camshaft 4, and the center portion of the cam timing belt pulley 1 is covered with a cup-shaped holding plate 16. The dowel pin 15 provided at 16 is fitted into the fitting hole 22. As shown in FIG. 2, this cup-shaped presser plate 16 includes a cylindrical portion 16b formed approximately at right angles to the contact surface with the cam timing belt pulley 1, and a cylindrical portion 16b formed at a right angle to the contact surface with the cam timing belt pulley 1, and the fixing bolt 13.
and a tightening seat portion 16c, the cylindrical portion 16
A dowel pin 15 for positioning the cam timing belt pulley 1 with respect to the camshaft 4 is integrally provided at b.

The bolt insertion hole 12 provided in this presser plate 16 and the cam timing belt pulley 1
By inserting one fixing bolt 13 into the axial center hole 8 of the cam and tightening the fixing bolt 13 on the tightening seat portion 16c of the presser plate, the tightening force is applied to the cam through the cylindrical portion 16b of the presser plate. The cam acts on the timing belt pulley 1 and fixes the cam timing belt pulley 1 to the end surface of the camshaft 4.

According to such a configuration, the tightening force of the fixing bolt 13 acts on the cam timing belt pulley 1 through the cup-shaped holding plate 16 and only from the cylindrical portion 16b of the holding plate. Therefore, a portion of the cam timing belt pulley 1 that is relatively distant from the center is pressed uniformly along the circumferential direction and is brought into pressure contact with the end surface of the camshaft 4, so that the cam timing belt pulley 1 4, can be installed perpendicularly, accurately, and firmly. As a result, the vibration of the pulley itself during rotation is effectively suppressed, eliminating the risk of increasing noise or reducing the durability of the belt.

Further, the knock pin 15 is connected to the presser plate 16.
Since it is configured to be fixed to the cylindrical portion 16b of the dowel pin 15, when the dowel pin 15 and the presser plate 16 are formed separately and then integrated by press-fitting, a sufficient press-fitting allowance for the dowel pin 15 can be secured, and the dowel pin 15 The cam timing belt pulley 1 can be accurately positioned without being press-fitted at an angle or wobbling.

Furthermore, as described above, the dowel pin 15 is made to protrude from the open end surface 16a of the presser plate 16, and when the presser plate 16 is attached to the center of the cam timing belt pulley 1, the dowel pin 15 is attached to the cam timing belt. Since the timing belt is passed through a positioning hole provided on the pulley 1 side and then fitted into a fitting hole provided on the end face of the camshaft 4, the timing belt can be easily assembled.

That is, according to the assembly method of the present invention, first, the cam timing belt pulley 1 is placed in a state in which the knock pin 15 integrally provided on the cup-shaped holding plate 16 does not fit into the notch 10 of the cam timing belt pulley 1. Then, temporarily attach it to the camshaft 4 as shown in Fig. 4 (at this time, the cam timing belt pulley 1 can rotate regardless of the camshaft 4). Next, as shown in Fig. 3, attach the crank pulley 21 to the matching mark. 17 and timing belt 2
Hang the timing belt 2 on the crank pulley 21 so that the alignment mark 18 of the cam timing belt pulley 1 aligns with the alignment mark 18 of the cam timing belt pulley 1. Hang the timing belt 2 on the timing belt pulley 1 as well. And cam timing belt pulley 1
When the fitting hole 22 of the camshaft 4 and the notch 10 of the cam timing belt pulley 1 are aligned, the knock pin 15 integrally provided on the cup-shaped holding plate 16 is fitted into the fitting hole 22. At the same time, the holding plate 16 is tightened with the bolt 13. In this way, the timing belt 2 can be easily installed accurately and with the designed tension.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing one embodiment of the present invention;
The figure is a perspective view of the presser plate in the same embodiment, FIG. 3 is a perspective view showing how the timing belt is assembled in the same example, and FIG. 4 is a temporary attachment state when assembling the presser plate in the same example. FIG. 1...Cam timing belt pulley, 4...Camshaft, 13...Fixing bolt, 15...Knob pin, 16...Cup-shaped holding plate.

Claims (1)

[Scope of utility model registration request] A cam timing belt pulley made of sheet metal is attached to the end face of the camshaft of the engine with a single bolt that passes through the center of the presser plate and the cam timing belt pulley and is screwed to the axis of the camshaft via a presser plate. In the mounting structure for a fixed timing belt pulley, the presser plate is composed of a cylindrical portion formed substantially perpendicular to the contact surface with the cam timing belt pulley and a tightening seat portion for the bolt, and The cylindrical portion of the presser plate includes a dowel pin which is configured in a cup shape such that it contacts the cam timing belt pulley only at the shaped portion, and which penetrates the cam timing belt pulley to position the timing belt pulley with respect to the camshaft. A mounting structure for a sheet metal cam timing belt pulley that is fixed to the