JPS626244Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a camshaft in an internal combustion engine valve system. Specifically, the cam plate has a divided structure for each unit and is made of ceramic that is wear-resistant even at high temperatures, and is fixed to a steel shaft. This invention relates to a split-type camshaft using ceramic with a bonded structure that eliminates stress concentration.

Traditionally, camshafts were manufactured as an integral part by cutting out cast or forged steel, but steel cams did not have sufficient wear resistance for modern internal combustion engines that aim to be high-speed, high-output, and maintenance-free. .

Therefore, in view of the above points, the present invention has a split-type camshaft, and uses ceramic with excellent wear resistance for the cam plate, which is subject to high pressure and high friction, and is easy to assemble and reduces stress concentration on the cam plate. The gist of this invention is that the camshaft is made of steel, the cam plate is manufactured individually from ceramic, and the cam plate has a round hole passing through the center of rotation and a hole on both sides. The shaft is inserted into the hole of the cam plate, and the radially expanding groove of the cam plate is formed in the steel flange. The cam plate is characterized in that the corresponding chevron-shaped protrusions are fitted into V-shaped grooves on both sides of the cam plate, and the flanges are fixed to the shaft by welding or brazing.

Embodiments of the present invention will be described below based on the drawings. 1 is the shaft of the camshaft, which is made of steel. 2 is a ceramic cam plate obtained by, for example, grinding necessary parts of a ceramic sintered body obtained by press-molding ceramic raw material powder into a predetermined shape and sintering it under pressure, and has a single lift, and its center of rotation is A through hole 3 is cut through the shaft 1, and V-shaped grooves 4 of equal depth are equally formed on both sides of the hole and radially spread at equal angles from the center of the hole.
Ceramic materials include Al ₂ O ₃ , Si ₃ N ₄ ,
Select and apply materials such as SiC and ZrO ₂ . Reference numeral 5 denotes a flange made of steel, which has a hole 6 cut therein to be fitted into the shaft 1, and a flange 5 having equal heights extending radially from the center of the hole 6 at equal angles corresponding to the V-shaped groove 4 on one side. The chevron-shaped protrusions 7 are formed equally. The bottom of the V-shaped groove 4 and the top of the chevron-shaped protrusion 7 are dimensioned so that they do not come into close contact with each other.

To assemble a camshaft with such a component configuration, the flange 5 is fitted onto the shaft with the side surface on which the chevron-shaped protrusion 7 is formed facing the shaft insertion side, and then the inside and outside are polished to form the V-shaped grooves 4 on both sides. Then, with the side surface on which the chevron-shaped protrusion 7 was formed facing the cam side, the flange 5 was inserted into the shaft 1 and both flanges 5, 5 were crimped to the cam plate 2 at a predetermined mounting position. Connect rear flanges 5, 5 to shaft 1
Weld or braze to fix in rotational and axial directions. If the temperature to be fixed is raised to approximately 140 degrees, which is the temperature of the atmosphere to which the camshaft is exposed during operation, rather than at room temperature, there is no risk of the cam loosening during operation of the camshaft. Or, as shown in Fig. 3, the split groove 8 is located at the center of the chevron-shaped protrusion 7 or on one side.
If a bending allowance is made on at least one side 7a of the protrusion cut by cutting and then flexed slightly while crimped at room temperature to give a spring effect, it will loosen due to thermal expansion during high temperature operation. There's no fear. Furthermore, it is also possible to prevent rotation in the axial direction with a key or to screw a locking bolt from the side of the flange. Furthermore, although eight grooves were provided in this embodiment, this objective can be achieved if the grooves are equally spaced at at least three places.

As detailed above, according to the present invention, since the cam plate is made of ceramic material, it can of course be adapted to the high rotation and high output of internal combustion engines. The cam plate is formed with a groove and is held from both sides by a flange having a radial protrusion corresponding to the groove on one side, so that the cam plate is automatically aligned and centered by the radial groove and protrusion. There is. Therefore, since a gap is formed between the inner diameter of the cam plate and the outer diameter of the shaft, there is no need to grind the inner diameter of the cam. Further, the stress on the cam plate during cam operation is dispersed over all the grooves, and no concentrated stress occurs at all, and there is no breakdown of the ceramic due to stress. Furthermore, the difference in thermal expansion between the ceramic material of the cam and the steel material of the flange is absorbed by the degree of freedom in the radial direction of the radial groove.

[Brief explanation of the drawing]

FIG. 1 is a side view of the cam plate attached, FIG. 2 is a front view of the cam plate attached, and FIG. 3 is a view showing another embodiment in which a groove is cut into the chevron-shaped protrusion of the flange. 1... Shaft, 2... Cam plate, 4... V-shaped groove, 5... Flange, 7... Chevron-shaped protrusion.

Claims (1)

[Scope of utility model registration request] In a camshaft that is a component of an internal combustion engine valve system, the shaft is made of steel and the cam plate is made of ceramic.The cam plate has a predetermined cam profile and has a hole passing through the center of rotation and a hole on both sides. The shaft is inserted into the hole of the cam plate, and the shaft is inserted into the hole of the cam plate. A split type camshaft using ceramic, characterized in that the protrusions are fitted into V-shaped grooves on both sides of the cam plate, and the flanges are fixed to the shaft by welding or brazing.