JP2895412B2 - Variable valve timing mechanism - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve timing mechanism capable of changing the operation timing of a valve that controls intake and exhaust during operation of an internal combustion engine. 2. Description of the Related Art As a variable valve timing mechanism of this type, a housing having teeth formed on the inner periphery is provided on the outer periphery through a ring gear in which at least one of the teeth formed on the inner and outer periphery is a helical tooth. The housing, which is rotationally driven by the engine, is relatively rotated with respect to the camshaft by moving the ring gear by attaching the lubricating oil pressure of the engine as a control oil pressure in the axial direction of the ring gear by attaching the camshaft to the camshaft having teeth formed thereon. In some cases, the opening / closing operation timing of the valve is changed (for example, US Pat. No. 4,231,330). [0003] In such a conventional variable valve timing mechanism, the housing is rotationally driven in connection with the crankshaft of the engine by a metal chain. Leakage of the control oil supplied to the movement of the ring gear to the outer periphery of the housing is considered to be preferable for lubrication of the chain, and the oil leakage is configured without special care. [0004] However, the drive by the metal chain causes a considerable amount of noise, and if a belt made of resin or rubber is used instead of the metal chain as a solution to this problem, the above-mentioned problem can be solved. The control oil was liable to cause early deterioration and slippage due to leakage of the control oil. [0005] Means for solving the problems [0005] From the camshaft end to the front
A control hydraulic passage opening to the pressure chamber is provided inside the camshaft.
And inside the housing facing the pressure chamber.
The peripheral surfaces were formed integrally without sliding contact with each other . The housing driven by the engine is rotated relative to the camshaft by moving the ring gear by applying a control oil pressure in the axial direction of the ring gear, and is driven by the camshaft. The opening / closing operation timing of the intake or exhaust valve is made variable. At this time, since the inner peripheral surfaces of the housing that define the pressure chamber in which the control hydraulic pressure acts do not have a portion that slidably contacts each other, it is possible to prevent the control oil from leaking to the outer periphery of the housing via the sliding contact portion. FIG. 1 is a sectional view showing an embodiment of the present invention. In the figure, reference numeral 1 denotes a housing, 2 denotes a ring gear, and 3 denotes a camshaft for controlling opening and closing of an intake or exhaust valve (not shown). The camshaft 3 is rotatable integrally with the camshaft 3 in this embodiment. External teeth 6 are formed on the outer periphery of the hollow shaft 5 connected to the key 4 as much as possible. The housing 1 has a pulley 1c driven by an engine (not shown) on the outer periphery, and has internal teeth 7 formed on the inner periphery. The ring gear 2 has an inner tooth 8 and an outer tooth 9 which mesh with the outer teeth 6 of the camshaft 3 and the inner teeth 7 of the housing 1, respectively, at least one of which is formed as a helical tooth. I have. Housing 1 is in front
Kamushafu protruding institution outside via the serial ring gear 2
It has been interlocking the end of the bets 3, become rotatable relative with respect to the camshaft 3 during axial movement of the ring gear 2
Have . At one axial end of the ring gear 2 (the left end in the figure), a control hydraulic passage ( hereinafter referred to as a " control hydraulic passage" ) provided in the camshaft 3 is provided.
The oil pressure is adjusted to a desired pressure by a control valve 11 behind the oil passage 10 and the oil passage 1 of the hollow bolt 12 for attaching the oil passage 10 and the hollow shaft 5 to the camshaft 3.
The control oil guided through 2a is acted on via a piston 13 which can move integrally with the ring gear 2, and is disposed at the other end (the right end in the figure) of the ring gear 2 so as to oppose the control oil pressure. Energize 14. Here, the control oil permits the use of engine lubricating oil, and the counterbalancing spring 14 facing the control oil pressure is provided with a recess 2a in the ring gear 2 in order to increase the degree of freedom in its design. One end is elastically contacted in the lever recess 2a. One end of the housing 1 facing the pressure chamber 30 is opened.
The end plate 16 is bolted to the mouth with the packing 15 in between.
... tighten, Aru the pressure chamber 30 is fluid-tightly sealed. That is, the pressure chamber 30 on which the control oil pressure acts.
Is defined by an inner peripheral surface 1d of the housing (formed by the inner peripheral surface of the housing end 1a and the inner peripheral surface of the end plate 16) and a piston 13 provided on one end side of the ring gear 2. The other end of the housing 1 has a cam cover 1 including a bearing 18 for bearing the camshaft 3.
Together they are arranged in 9, fluid-tight seal by the sealing 20 is applied. An oil recovery hole 2 formed in the cam cover 19 is provided between the housing end 1b and the cam shaft 3.
1 is formed with an oil leakage return passage 22. An annular groove 23 is formed on the inner periphery of the bearing 18 of the cam cover 19 to communicate with an oil passage 24 through which the control oil from the control valve 11 is guided. 10 is always in communication during the rotation of the camshaft 3. A part of the oil guided to the annular groove 23 leaks to the inner peripheral bearing surface of the bearing 18 to lubricate it. Reference numeral 25 denotes a toothed belt made of resin, rubber, or the like, which is wound around the pulley 1c and correctly transmits the rotation of the engine to the pulley 1c. Reference numeral 26 denotes a cover for covering the rotating portion of the variable valve timing mechanism. The cover 26 prevents exposure of the rotating portion to ensure safety and minimizes noise generated when the pulley 6 contacts the belt 25. Hide inside it. In the variable valve timing mechanism configured as described above, the rotation of the housing 1 driven through the belt 25 is transmitted to the camshaft 3 through the ring gear 2, and the camshaft 3 opens and closes an intake or exhaust valve (not shown). While the control is being continued, the control oil pressure guided from the control valve 11 is applied to one end of the ring gear 2 via the piston 13 to move the ring gear 2 against the spring force of the balancing spring (to the right in the drawing). Thus, the relative position of the housing 1 and the camshaft 3 in the rotation direction is changed, and the operation timing of the intake or exhaust valve controlled by the camshaft 3 is changed. At this time, the housing 1 facing the pressure chamber 30
The control oil does not leak out of the housing 1 because the one end side opening is sealed by the end plate 16. In particular, the end plate 16 and the housing end 1a are
As a result, the hydraulic oil is integrally fastened without sliding contact with each other, so that hydraulic oil does not leak through the sliding contact portion. A part of the control oil that presses the ring gear 2 is used to lubricate the mesh gap between the ring gear 2 and the housing 1 and the camshaft 3 so that the piston 13 can be fitted into the housing 1 and the camshaft 3. However, this oil can be returned to an oil pan (not shown) through the oil return path 22 and the oil recovery hole 21, and does not leak out of the housing 1. Further, since the housing 1 is rotationally driven by the belt 25 made of resin or rubber, the driving noise can be reduced as much as possible, and the driving noise can be reduced by the cover 26 covering the rotating part. Can be shielded. In this embodiment, the control oil pressure is applied to the ring gear 2 through the piston 13. However, the piston 13 may be integrated with the ring gear 2, and similarly, the hollow shaft 5 is integrated with the camshaft 3. Is also good. According to the present invention as described above,
Since the inner peripheral surfaces of the housing facing the pressure chambers where the control oil pressure acts are formed integrally without sliding contact with each other, the inside of the housing is sealed in a liquid-tight manner, preventing the control oil from leaking out of the housing. it can. Further, as a result that the control oil can be prevented from leaking to the outside of the housing, a belt made of resin or rubber can be used for driving the housing, and the driving noise can be reduced as much as possible.

[Brief description of the drawings] FIG. 1 is a sectional view showing an embodiment of the present invention. [Explanation of symbols] 1 ... Housing 1a, 1b ... housing end 1c ... Pulley 1d ... inner peripheral surface of the housing 2. Ring gear 3. Camshaft 14 ... Balancing spring 30 ... pressure chamber

Claims (1)

(57) [Claims] A housing provided with a pulley driven by the engine on the outer periphery is provided outside the engine via a ring gear in which at least one of the teeth created on the inner and outer periphery is a helical tooth.
In tandem to the end of the protruding cam shaft, without a relatively rotatable with a camshaft in the axial direction movement of the ring gear, provided the pressure chamber in the one axial end of the ring gear, said pressure chamber In a variable valve timing mechanism, which applies control hydraulic pressure to a counterbalance spring disposed on the other end opposite to the control oil pressure, the valve is fixed to one end opening of the housing facing the pressure chamber.
An end plate for sealing the pressure chamber in a liquid-tight manner, and an opening on the other end side of the housing is pivoted around the camshaft.
A control oil disposed in a cam cover for receiving and opening the pressure chamber from an end of the cam shaft.
A variable valve timing mechanism , wherein a pressure passage is formed in the camshaft .