JPS6081412A - Valve-timing controller for engine - Google Patents

Abstract

PURPOSE:To allow turning members to resist each turning moment received from a cam by allowing the turning member for holding each tappet in slidable ways to turn around a cam shaft by the worm gear on a control shaft. CONSTITUTION:The tappets 20 and 21 for transmitting the respective lifts of cams 22a and 23a to valves 12 and 13 are installed in slidable ways into turning members 26 and 27 installed rotatably around cam shafts 22 and 23, and each opening and closing timing of the valves 12 and 13 can be controlled by adjusting each position of the turning members 26 and 27. The turning members 26 and 27 of the respective cylinders are connected by connecting shafts 32 and 33, and each worm gear is formed onto the projections 32a and 33a of the connecting shafts 32 and 33a, and said gears are geared with the worm gears 36 and 37 on control shafts 28 and 29. Each turning force which each turning member 26, 27 receives from the cam is received by a worm gear 36, 37, and thus each position of the turning members 26 and 27 is held.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a valve timing control device for an engine.

[Prior art]

In general, an engine valve timing control device variably controls the opening/closing timing of intake and exhaust valves of the engine in accordance with the operating state of the engine, thereby attempting to operate the engine at a high rate of 9). As an example of this valve timing control device, as shown in Japanese Patent Publication No. 52-35819, a planetary gear mechanism controlled by a centrifugal governor is provided between the output shaft of the engine and the camshaft, and the engine There is a system in which the centrifugal force generated by the rotation of the output shaft and the camshaft is used to create a phase difference between the rotations of the output shaft and the camshaft, thereby variably controlling the valve timing. In another device, a camshaft is formed with a cam surface having a different profile in the axial direction, and the camshaft is slid in the axial direction, thereby variably controlling the valve timing.

However, the former valve timing control device described in the prior art publication has a problem in that it has a complicated structure and cannot change the valve timing in accordance with operating conditions other than the engine speed. On the other hand, the latter device also has a complicated structure, and since the camshaft is made to slide in the axial direction, there are problems in that the responsiveness and reliability of the operation are poor.

In response, the present applicant rotatably supports a rotating member on the camshaft, and also slidably fits a tappet for transmitting force to the valve stem into the fitting hole of the rotating member. The above-mentioned rotating member and a control shaft slid by an actuator such as an electromagnetic solenoid are interlocked and connected, and the actuator rotates the rotating member according to the operating state of the engine to press the cam surface against the tappet. We have already developed a system in which valve timing can be controlled variably by changing the timing (Japanese Patent Application No. 57-17).
No. 5578). The valve timing control device with this structure has the advantage that it has a simpler structure than the conventional device and can be expected to operate reliably due to its structure. In order to solve this problem, it is necessary to hold and control the actuator, such as by keeping current flowing through the electromagnetic solenoid. Durability may decrease.

[Purpose of the invention]

This invention was made under such circumstances, and is an attempt to further develop the engine valve timing control device developed by the applicant and to prevent the rotating member from reversing without holding and controlling the actuator. be.

[Structure of the invention]

Therefore, the present invention provides an engine valve timing control device in which valve timing is variably controlled by rotating a rotary member (51) having an internal tappet around a camshaft. The control shaft and the rotating member are connected by a worm gear.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1 and 2 show an engine valve timing control device according to an embodiment of the present invention, and this is an example applied to a dual induction type four-cylinder engine.

In the figure, reference numeral 1 denotes an engine having four cylinders 2a to 2d, the first to fourth cylinders, each of which has intake bows 3a and 3b for high load and low load, respectively.
．． Second exhaust boats 4a, 4b are formed, and each boat 3a, 3b, 4a, 4b is provided with intake and exhaust valves 5a, 5b, 6a, 6b for opening and closing them. In addition, the intake boats 3a and 3b have intake manifolds 7a and 7.
b is the exhaust port 4a.

Exhaust manifolds 8a and 8b are respectively connected to the intake manifold 7 of the high-load intake boat 3a.
An on-off valve 9 that is opened during high load is disposed in the middle of a, and each of the cylinders 2a to 2dW is connected only to the low load intake boat 3b during low load, and from the high load and low load intake boats during high load. Intake air is supplied from both load intake boats 3a and 3b.

The engine 1 also includes the intake and exhaust valves 5a.

Intake-side and exhaust-side valve operating devices 10.11 are provided for opening and closing the valves 5b, 6a, and 6b, respectively. In this valve train 10.11, intake and exhaust valves 5a, 5b, 6a
, 6b (however, only the valve stems of one set of intake and exhaust valves 5a, 6a are shown in the figure) are connected to the valve guide 14. ．． Engine 1 through 15
The valve stem 12 is supported on the cylinder head 1a of the valve stem 12.
．． A retainer 17 is installed near the upper end of 13 via a cock 16.
is attached, and valve springs 18, 19 are disposed between the retainer 17 and the cylinder head 1a to bias the valve stems 12, 13 upward. Also, above the valve stem 12.13 is a cylindrical cupeno 1-20.21.
Suction and exhaust valves 5a, 5b, 6a, 6 are provided above the tappet 20.21 via the tappet 20.21.
camshafts 22, 23 are provided which press b, and the camshafts 22, 23 are connected to the engine crankshaft (not shown) via a timing belt 24,
It is designed to be rotated by the output of the engine.

Furthermore, the engine 1 has one set of suction out of the two sets described above,
A variable valve timing mechanism 25 is provided to variably control the opening and closing timing of the exhaust valves 5a, 5a. This variable mechanism 2
5, 26.27 is a rotating member having fitting bag holes 26a and 27a into which the above-mentioned taposo) 20.21 is slidably fitted;
6.27 is a rotating member 2G rotatably supported around a camshaft 22.23.

An interconnected control shaft 28.29 is arranged above the control shaft 28.27.
Reference numeral 29 is rotated by a motor 30 according to the engine speed.

The central projections 32a and 33a of the connecting shaft 32.33 connecting the left and right rotating members 26.27 are machined with worm gears in mutually opposite directions, while the control shaft 28.29 is machined with worm gears in the central Projections 32a, 33
A worm gear 34.35 is formed which also has oppositely cut teeth meshing with the worm teeth of a, such that said pivot member 26.27 and control shaft 28.29 are connected to said worm teeth. and worm gear 3
4.35, and rotation of the control shaft 28.29 in the same direction causes the rotation members 26.27 to rotate in mutually opposite directions around the cam shirts 2 and 23. It is designed to be moved.

Also, the other of the two sets of intake and exhaust valves 5b.

6b valve train 10. In II, the tappet 2
0.21 is supported by the throat 1a of the cylinder, so the opening and closing timings of the intake and exhaust valves 5b and 6b are always constant.

Next, the operation will be explained using FIG. Here the third
The figure shows the opening/closing timing of the intake and exhaust valves 5a, 5b, 6a, 6b (7) when the engine is running at low speed and when the engine is running at high speed.

When the engine is operated, the camshaft 22.23 rotates in synchronization with the engine, and the cam surfaces 22a, 23a of the camshaft 22.23 press the intake and exhaust valves 5a to 6b via the tappets 20 and 21. The intake and exhaust valves 5a to 6b open and close the intake and exhaust ports t-3a to 4b. When the engine is under low load, the on-off valve 9 of the intake manifold 7a on the high load side is kept fully closed, and each cylinder 2a to 2d is closed.
Intake air is supplied only from the low-load intake port 1-3b.

When the engine is under high load, the on-off valve 9 of the high-load side intake manifold 7a is opened, and intake air is supplied to each cylinder 2a to 2d from both the high-load and low-load intake ports 3a and 3b. The Rukoto. During this high load, when the engine is running at low speed, the variable valve timing mechanism 25 is not operating, and the center lines a and b of the rotating members 26 and 27 are the center lines of the intake valves 5a and 6a, and the center lines of the exhaust valves 5a and 6a. C2
The state is almost the same as d. In this state, the intake and exhaust valves 5a, 5b, 6a, and 6b are connected to the dotted line 11 in FIG.
It opens and closes at the timing shown by El. That is, the exhaust valves 6a, 6b open near the piston bottom dead center BDC, and then close near the piston top dead center TDC, and the intake valves 5a, 5 open near the piston top dead center TDC.
b opens near the piston top dead center TDC and then closes near the piston bottom dead center BDC.

Next, when the engine rotates at high speed under this high load,
The motor 30 rotates the control shafts 28, 29, respectively, and the rotation of the control shafts 28, 29 is controlled by the rotation member 26, 27 by a worm gear 36, 37.
The rotating members 26, 27 are transmitted to the camshaft 22.
．． 23 in the direction of the arrow, direction B, i.e. cam shirt)
22. It rotates in the same direction as the rotation direction of 23, and in the opposite direction. In this state, the timing at which the tappet 21 of the cam surface 23a of the camshaft 23 in the exhaust example is pressed becomes earlier, and the timing at which the tappet 20 of the cam surface 22a of the camshaft 22 on the intake side is pressed is delayed. As shown by the solid line E2 in FIG. 3, the valve 6a opens and closes at a timing that is advanced compared to the opening and closing timing of the other exhaust valve 6b (see the broken line E1 in FIG. 3), and the intake valve 5a is shown by the solid line in FIG. As shown by (2), the intake valve 5b is opened and closed at a timing that is delayed compared to the opening and closing timing of the other intake valve 5b (see the broken line (1) in FIG. 3).

In this way, when the engine is under high load and at low speeds, the exhaust valve opens and closes late during the engine's explosion stroke, so that the expansion force is transmitted to the piston without wastage, and during the intake stroke, the intake valve opens and closes early, which slows down the intake flow rate. In addition to ensuring a sufficient amount of intake air, a reduction in filling efficiency due to intake air blowback is prevented, resulting in a significant improvement in fuel efficiency. Also, when the engine is under high load and at high speeds,
During the exhaust stroke, one exhaust valve opens and closes quickly, allowing the exhaust to be discharged quickly and reducing piston resistance.
By opening and closing one intake valve late during the intake stroke, the overall opening time of the intake valve becomes longer, and the amount of intake air increases due to inertia force, improving charging efficiency, resulting in high engine output. I can do it.

Since the control shaft and the rotating member are connected by a worm gear, even if the pressing force of the cam acts on the rotating member, the rotating force of the rotating member is transmitted to the control shaft via the worm gear and the control shaft is controlled. The shaft does not rotate, and as a result, reversal of the rotating member is reliably prevented. In addition, as the control shaft does not rotate due to the rotational force of the rotating member, there is no need to apply a constant torque to the motor, which eliminates the need for motor holding control and guarantees the durability of the motor. can.

In addition, in this device, a variable valve timing mechanism is provided to change the valve timing of each of the intake valve side and the exhaust valve side, and the variable mechanism is configured with a worm gear mechanism.
The valve timing of the intake valve and exhaust valve can be controlled independently using two actuators, and as a result, the valve timing can be controlled optimally according to the operating state of the engine, and the engine can be operated efficiently.

In the above embodiment, a case has been described in which the present invention is applicable to a dual induction type 4-valve engine, but the present invention can be similarly applied to a 2-valve engine having one intake boat and one exhaust boat. Further, the variable valve timing mechanism does not have to control the intake valve side and the exhaust valve side in opposite directions, but may control both sides in the same direction.

Further, in the above embodiment, a case has been described in which the valve timing of both the intake and exhaust valves is controlled, but the present invention can be similarly applied to a case where the valve timing of either the intake or exhaust valve is controlled. Further, the method of controlling the valve timing may be different from that of the above embodiment.

Furthermore, control of valve timing is not limited to being performed in accordance with engine speed, but may be performed in accordance with load and other operating conditions of the engine. Furthermore, the amount of change in valve timing can be determined by setting the gear ratio or gear pitch of the worm gear mechanism to different values for the intake valve side and the exhaust valve side, and for the same rotation amount of the control shaft, the intake valve side and the exhaust valve side The amount of change may be different depending on the requirements of the engine.

〔Effect of the invention〕

As described above, according to the engine valve timing control device according to the present invention, the worm gear connects the rotating member that changes the valve timing by rotating the rotating member and the control shaft that rotates depending on the operating state of the engine. Since the rotating member is rotated by the rotation of the control shaft, there is no need to hold and control the actuator, and the durability of the actuator can be guaranteed.
Further, there is an effect of reliably preventing the rotating member from reversing.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an engine valve timing control device according to an embodiment of the present invention, FIG. 2 is a sectional view of the main parts of the device, and FIG. 3 is an intake and exhaust diagram for explaining the operation of the device. It is a figure showing the opening and closing timing of a valve. 5a, 6a... Suction and exhaust valves, 12.13... Halb stem, 20.21... Tappet, 22.23...
Camshaft, 22a, 23a...cam surface, 26,2
7... Rotating member, 26a, 27a... Fitting hole, 28
゜29...Control shirt l-136, 37...
・Worm gear. Patent applicant: Toyo Kogyo Co., Ltd. Representative Patent attorney: Ken Hayase −

Claims (1)

[Claims] (1) An engine valve timing control device that variably controls valve timing according to engine operating conditions, which includes a tappet that transmits force from the cam surface of the camshaft to the valve stem, and a tappet that is slidable. a rotating member that has a fitting hole for fitting and is rotatably supported around the camshaft to vary valve timing; a control shaft that rotates according to the operating state of the engine; and a control shaft that rotates with the control shaft. 1. A valve timing control device for an engine, comprising: a worm gear coupled to a worm gear for rotating the rotating member around a camshaft by rotation of the control shaft.