JPS59110819A - Valve timing varying device - Google Patents

Abstract

PURPOSE:To improve an output and fuel consumption, by a method wherein, in an OHV type dynamic valve, a hydraulic spring load regulator in which, as a speed is decreased, the set load of a valve spring is set to an increased value, is mounted, and valve timing during low speed and high speed operation is controlled to an optimum mode. CONSTITUTION:An OHV type dynamic valve mechanism 1 is constituted such that a suction and exhaust valve 4 makes contact with the one end of a locker arm 3 supported by a locker shaft 2, and a push rod 7, coupled with a cam 5 through a tappet 6, makes contact with the other end thereof. Further, valve springs 10 are attached on the valve 4 side between a retainer 8 and a cylinder head 9. A hydraulic spring load regulator 11 is located on the cylinder head 9 side to the lower end of the valve spring 10. In response to a signal provided according to the number of revolutions of an engine detected by a sensor 14, a drive motor 17 of an oil pump 16 is controlled through a control circuit 15, and an oil pressure, which is increased with the decreased speed, is fed to a cylinder 12 of the regulator 11 through an oil passage 18.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable valve timing device that varies the opening and closing timing of a valve in a valve train of an internal combustion engine. Concerning things that change.

In general, valve timing in the valve train of an internal combustion engine is determined by adjusting the opening and closing timing of the intake and exhaust valves in order to reduce and stabilize losses such as intake air blow-through and exhaust blow-out when low-speed performance is important. Make the valve operating angle smaller by making it closer to the setting. On the other hand, when high-speed performance is important, in order to improve intake inertia fl and exhaust efficiency to increase volumetric efficiency,
It is necessary to set the opening and closing timing of the intake and exhaust valves farther from the dead center and increase the overlap as well as the valve operating angle.

Incidentally, conventionally, the cam lift, phase, valve clearance, etc., which determine such valve springs, are generally fixedly set to one of the above-mentioned low-speed and high-speed applications. Therefore, there was a problem in that it was not possible to obtain optimal valve timing under both low-speed and high-speed operating conditions.

In view of these circumstances, the present invention makes the valve timing variable so that the repulp operating angle becomes smaller or larger in operation condition (1), and optimally controls the valve timing at low speeds and high speeds to improve output, fuel consumption, etc. Improved variable valve timing 4! The purpose is to provide

For this purpose, the device according to the present invention has a long push rod, rocker arm, etc. between the cam and the valve in the O-1V type valve train, and changes the set load of the valve spring to deflect the bush rod, etc. By focusing on the fact that the valve lift amount and timing can be changed with respect to the cam lift amount, we installed a hydraulic spring load adjustment device on the opposite side of the valve spring retainer, increasing the set load of the valve spring at low speeds and adjusting the bushing rod. etc. to reduce the stroke and make the valve lift small. At high speeds, the set load of the valve spring is reduced and the bushing rod has a sufficient stroke, and the valve operating angle is made large according to the cam profile. It is something to do.

Incidentally, as prior art related to the present invention, for example,
No. 4-173120, the valve timing is made variable by changing the intermediate support position of the rocker arm. However, in this prior art, the valve timing is adjusted for each engine when the cam is shared in a multi-insert engine, and this is completely different from the present invention in which the valve timing is made variable depending on the operating conditions.

3- Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings. In FIG. 1, reference numeral 1 denotes an OHV type valve mechanism, which is sucked into one side of a rocker arm 3 supported by a rocker shaft 2 in a scale-like manner.

Alternatively, the stem end of the exhaust valve 4 contacts the other end, and the bushing rod 7 connected to the cam 5 via the tappet 6 contacts the other end. On the valve 4 side, a valve spring 10 is biased between a retainer 8 at the stem end and a cylinder head 9, and the rotation of the cam 5 swings the tappet 6 and bushing rod 7, thereby swinging the rocker arm 3. This moves the valve 4 to open the valve.

Therefore, the valve spring 10 of such a valve train mechanism 1 is
A hydraulic spring load adjustment device 11 is provided on the cylinder head 9 side at the lower end, and this device 11 has a donut-shaped cylinder 12 formed right below the valve spring 10, and a donut-shaped piston 13 inside this cylinder 12 to adjust the valve spring. It supports the lower end of 10. Further, the drive motor 17 of the oil pump 16 is controlled via the control circuit 15 by a signal corresponding to the engine rotation speed from the rotation sensor 144-, and as a result, high oil pressure is applied to the low-speed culm via the oil passage 18 as shown in FIG. As a result, the set load of the valve spring 10 is large at low speeds, and is reduced at high speeds.

With this configuration, during low-speed operation, the set load of the valve spring 10 is increased by the action of the hydraulic spring load adjustment device 11, and therefore the movement of the valve 4 is significantly restricted elastically. Therefore, when the cam 5 lifts, the long bushing rod 7, which is particularly easily deformed, elastically bends due to the large restraining force of the valve spring 10, and the valve 4 opens and closes. The lift characteristics of the cam 5 and the valve 4 are reduced accordingly, and the timing of the intake and exhaust valves becomes one with a small valve operating angle α, as shown by the broken line in FIG.

On the other hand, in high-speed operation, the set load of the valve spring 10 is reduced by the action of the device 111, and the restriction on the valve 45- is released, so that the bushing rod 7 and the like can be moved without being deformed. Therefore, when the cam 5 lifts, the bushing rod 7 etc. move in a normal state, and the valve 4 opens and closes according to the profile of the cam 5. Therefore, the valve timing of the intake and exhaust valves is as shown in Fig. 3. As shown by the solid line, the valve operating angle becomes large as α'.

In addition, variable control of the valve timing according to each operating condition can be performed arbitrarily using the hydraulic characteristics shown in Figure 2. Also good.

As is clear from the above description, according to the present invention, OHV
In the type valve mechanism 1, by using the set load of the valve spring 10 to change the amount of deflection of the bushing rod 7, etc., the valve timing is controlled to be optimal under each operating condition at low speeds and high speeds, so it is stable at low speeds. sex,
Both fuel efficiency and high-speed output can be improved. The hydraulic spring load adjustment device 11 allows the set load 6- of the valve spring 10 and the variable amount of valve timing to be set reliably and freely.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the loading capacity according to the present invention,
FIG. 2 is a hydraulic characteristic diagram, and FIG. 3 is a diagram showing valve timing. DESCRIPTION OF SYMBOLS 1... Valve mechanism, 2... Rocker shaft, 3... Rocker arm, 4... Suction and exhaust valves, 5... Cam, 6...
...Tappet, 7.Button rod, 8.Retainer, 9.Cylinder head, 10.Valve spring, 11.Hydraulic spring load adjustment system, 1.
2... Cylinder, 13... Piston, 14... Rotation sensor 4t, 15... Control circuit, 1G... Oil pump, 17... Motor, 18... Oil path. Patent Applicant Fujijuku Kuwa Co., Ltd. Agent Patent Attorney Makoto Kobashi Ukiyo Patent Attorney Village 1F Shin 7- Figure 1 Figure 2 Figure 3 ＼゛＼ 95- ＼-１

Claims (1)

[Claims] In an OHV type valve train, a hydraulic spring load adjustment device is installed on the opposite side of the valve spring retainer to increase the valve spring set load at low speeds. A variable valve timing device characterized by being configured to operate according to a cam profile.