JPS60119309A - Valve timing angle leading device of 4-cycle engine - Google Patents

Abstract

PURPOSE:To control the open and close timing of the suction/exhaust valve of an engine by providing grooves on each disc coupling a drive shaft and a cam shaft so that the grooves cross with each other and moving sliding pieces which are engaged both the grooves by the hydraulic pressure correspondent to the engine speed. CONSTITUTION:Discs 8 are provided in the coupling portion of a drive shaft 1 and a cam shaft 3. In the disc of the drive shaft 1 inclined grooves 7 are formed and in the disc of the cam shaft 3 radial holes 10 are provided and in the holes 10 sliding pieces 11 each having a projection 14 engaging with the inclined groove 7 is inserted. A hydraulic pressure which rises in proportion to the increase of the engine speed is applied to the hole 10 so as to move the sliding piece 11 outwards and lead the phase angle of a cam 4 and hasten the open and close timing of the suction/exhaust valve. In this construction, the filling efficiency is raised and the output can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pulp timing advance device for a four-stroke engine.

In a four-stroke engine, an intake cam and an exhaust cam are installed on a camshaft linked to the crankshaft, and the intake and exhaust valves are opened and closed by pushing down through rocker arms, respectively. Therefore, the opening/closing timing of the intake and exhaust valves is determined by the shape of each intake and exhaust cam. Since the gas flow cannot be followed as the engine rotates at high speed, it is desirable to advance the pulp timing to compensate. However, the conventionally proposed pulse timing and advance angle devices use a large number of gears, have a complicated structure, and are expensive to manufacture, making them impractical.

In view of this, this invention is an improvement in that the sliding piece is slid by the hydraulic pressure that increases as the rotation increases, and the camshaft is phased in the rotational direction with respect to the drive shaft to advance the pulp timing. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

A timing pulley 2 is connected to one end of the drive shaft 1, and is connected to a crankshaft (not shown) by a timing belt, and rotates in conjunction with the crankshaft.

A cam 4 is provided on the camshaft 3, and 40 rotations of the cam swings a rocker arm 5 to push down an intake valve or an exhaust valve 6 to open and close it. The drive shaft l has a diagonal groove 7.
The discs 8 provided with are connected together. On the other hand, to the core hole 9 of the camshaft 3, an oil pump linked to the engine sends hydraulic pressure whose pressure increases as the rotation increases. The tip of the core hole 9 is communicated with a radial hole 10, into which a sliding piece 1 is slidably inserted. The sliding piece 11 is urged inward by the blade 12. The sliding piece 11 is provided with a protrusion 14 that protrudes from the window hole 13 and is fitted into the diagonal groove 7 of the drive shaft 1.

Thus, when the drive shaft 1 rotates in conjunction with the crankshaft, the rotation is transmitted to the camshaft 3 via the diagonal groove 7 and the protrusion 14 of the sliding piece 11. The rotation of the cam 4 pushes down the intake and exhaust valves 6 via the p-locker arm 5 to open and close them. As the rotation of the engine increases, the oil pressure in the hole 10 increases, pushing the sliding piece 11 outward against the spring 2. Therefore, the protrusion 14 fitted into the diagonal groove 7 of the sliding piece 11 changes its position, and the camshaft 3 moves to the drive shaft 1.
The cam 4 is displaced in the rotational direction relative to the cam 4, and the cam 4 is advanced. Therefore, the opening/closing timing of the intake and exhaust valves 6 is advanced, the filling efficiency at high speeds is increased, and the output can be increased.

As explained above, this invention provides a disk with a diagonal groove on the drive shaft that is linked to the crankshaft, and a cam that opens and closes the intake and exhaust valves on one side of the camshaft. A sliding piece that is pushed and moved by the rising hydraulic pressure is accommodated, and the protrusion of the sliding piece is fitted into the diagonal groove of the drive shaft.
As the camshaft (camshaft) is displaced in the rotational direction as the rotation increases, the valve timing can be advanced as the rotation increases, increasing the filling efficiency at high speeds and increasing the output. can be achieved. Further, the part for advancing the angle can be provided on one side of the camshaft, which reduces the number of parts and can be manufactured at low cost.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which FIG. 1 is a partially longitudinal plan view, FIG. 2 is a side view, and FIG. 3 is an enlarged view taken along the line A--A in FIG. 1... Drive shaft, 3... Camshaft, 4... Cam. 6... Intake and exhaust valve, 7... Diagonal groove, 8... Disc,
1...Sliding piece, 14...Protrusion. Applicant's agent Kiyoshi Inomata 2nd Flffi

Claims (1)

[Claims] A disk with diagonal grooves is installed on the drive shaft that is linked to the crankshaft, and a sliding shaft is pushed and moved by the hydraulic pressure that increases as the rotation increases. The protrusion of the sliding piece is fitted into the diagonal groove of the disc, and the camshaft is displaced in the rotational direction with respect to the drive shaft as the rotation increases. Pulp timing advance device for 4-stroke engines.