JPH01138309A - Valve system of engine - Google Patents

Abstract

PURPOSE:To make a cam member run-up rotated to reduce the difference of rotation speed with a camshaft, and to smooth the combination, by contacting a clutch member to the cam member when a pin is operated to the position to combine the cam member to the camshaft. CONSTITUTION:To a camshaft 1, a cam 7 for low speed, and a cam 8 for high speed which composes a rotatable cam member are provided in parallel to be contacted freely to a tapet 5. And to a hole 11 formed at the low speed cam 7, is installed a pin 12 to convert the high speed cam 8 to the connected and unconnected conditions against the camshaft 1. In this case, to the camshaft 1, a clutch device having a clutch member 23 opposing to the side of the high speed cam 8, and the like, is installed additionally. The pin 12 and the clutch device 20 are operated by a hydaulic circuit 30 as a driving device. Therefore, when the pin 12 is operated to the combining condition, the clutch member 23 is operated to contact to the high speed cam 8.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention includes a cam member rotatably supported on a camshaft, and the cam member is switched between a connected state and a throat-connected state with respect to the camshaft. This relates to the engine valve train Sa that has been made possible.

(Prior art) Conventionally, in valve train systems that drive the intake and exhaust valves of an engine, a valve train is rotatably supported on a camshaft in order to stop the valve drive or change the valve lift characteristics depending on the operating condition. Some cam members include a cam member that can be switched between a coupled state in which the cam member rotates integrally with the camshaft and a non-coupled state.

For example, the valve stop device shown in Japanese Patent Application Laid-Open No. 59-155514 does not have a light load. In order to improve fuel efficiency by stopping the driving of some of the valves at 4 o'clock, the cam members corresponding to some of the valves are rotatably supported on the camshaft. A pin (plunger) is fitted into the hole so that it can move in the radial direction, and the pin is engaged and disengaged from the locking hole provided in the cam member, thereby making it possible to connect or disconnect the cam member from the camshaft. I am trying to switch between the state and the state. In the coupled state, the cam member rotates together with the camshaft to drive the valve, and in the non-coupled state, the cam member stands still and the valve is stopped from driving.

In addition, in order to change the valve lift characteristics between low and high engine speeds, two types of cam members are arranged on the camshaft: a low-speed cam with a relatively small cam nose and a high-speed cam with a larger cam nose. If the high-speed cam is rotatable with respect to the camshaft, then the high-speed cam and the low-speed cam fixed to the camshaft will be in a coupled state and a non-coupled state. By providing a pin that switches to the engaged position, when the pin is operated to the engaged position, the high-speed cam rotates together with the camshaft and the high-speed cam essentially drives the valve, and when the pin is operated to the disengaged position, the high-speed cam rotates together with the camshaft. There are some models in which the high-speed cam stands still and the low-speed cam drives the valve.

By the way, in these conventional devices, when switching the cam member from a non-coupled state to a coupled state with respect to the camshaft, either one of the rotating camshaft side and the stationary cam member side is switched. Since the pin held on the other side will engage with the locking hole formed on the other side,
There was a problem in that a large W71 impact load was applied to the pin, and the connection by the pin could not be performed smoothly.

(Object of the Invention) In view of the above circumstances, the present invention reduces the impact load applied to the pin when switching the cam member from the l-coupled state to the coupled state with respect to the camshaft by the operation of the pin,
In addition, the present invention provides an engine valve train position that can improve the reliability of pin connection.

(Structure of the Invention) The present invention includes a cam member rotatably supported on a camshaft, and is movable between a coupled position and a non-coupled position where the cam member is coupled to the camshaft so as to rotate together with the camshaft. In a valve train for an engine, the clutch is installed on the camshaft and has a clutch member that can be pressed against and separated from the cam member. and actuating means operative to press the clutch member against the cam member when the pin is actuated to the engaged position.

According to this configuration, when the cam member is switched from a non-coupled state to a coupled state with respect to the camshaft, the cam member rotates in a run-up manner due to the operation of the clutch member, thereby reducing the difference in rotational speed between the camshaft and the cam member. In this state, pin connection is performed.

(Embodiment) Figures 1 to 3 show an embodiment of the present invention.The embodiment shown in these figures is a direct drive type in which a cam directly drives a valve, and The present invention is applied to a valve train V4T in which valve lift characteristics are changed by selectively using two types of cams.

In these figures, a camshaft 1 is rotatably supported by a cylinder head (not shown) via a bearing 2, and rotates at a speed of 1 in conjunction with a crankshaft. Further, 3 is a valve (intake valve or exhaust valve) that opens and closes an intake boat or an exhaust boat that opens into the combustion chamber of the engine, and a tappet 5 is connected to the upper end of the valve stem via a hydraulic lash adjuster 4. installed. The valve 3 is biased in the valve closing direction by a valve spring 6.

Above the tappet 5, a low speed cam 7 and a high speed cam 8 forming a cam member rotatable with respect to the camshaft 1 are arranged side by side on the camshaft 1 at a position where they can come into contact with the tappet 5. has been done. The low speed cam 7 is
The cam nose 7a is formed relatively small and is fixed to the camshaft 1 so as to always rotate together with the camshaft 1. On the other hand, the high-speed cam 8 has a cam nose 8a larger than the cam nose 7a of the low-speed cam 7, and is rotatably attached to the camshaft 1 via a needle bearing 9.

The low-speed cam 7 has a pin storage hole 11 that opens on the side facing the high-speed cam 8, and the high-speed cam 8 is connected to the camshaft 1 in this pin storage hole 11. A pin 12 for switching between the camshaft and stave-coupled states is housed so as to be slidable in the axial direction of the camshaft. An oil passage 14 communicating with an oil passage 13 in the camshaft 1 communicates with the bottom side of the pin storage hole 11, and when hydraulic pressure is applied from this oil passage 14, the pin 12 opens the pin storage hole 11. It is designed to be operated in the direction of protruding from the section.

Further, the high-speed cam 8 is provided with a locking hole 15 into which the pin 12 is engaged and disengaged. This locking hole 15 is connected to both cams 7
．． The cam noses 7a and 8a of 8 are provided at positions that match the pin housing holes 11 of the low-speed cam 7 when they face in the same direction, and are open on the side surface corresponding to the low-speed cam 7. A receiver 16 for the pin 12 and a spring 17 that biases the receiver 16 toward the open end of the locking hole 15 are accommodated in the locking hole 15 .

A clutch device r120 is attached to the camshaft 1 on the side of the high-speed cam 8. This clutch equipment! 20 includes a clutch cover 21 fixed to the camshaft 1, a piston member 22 disposed inside the clutch cover 21, and an annular ring located at the tip of the piston member 22 and facing the side surface of the high-speed cam 8. Clutch member 2
3 is on the right. The piston member 22 is coupled to the clutch cover 21 by a slide key 24 so as to be slidable and rotate together with the clutch cover 21.

An oil passage 25 communicating with the oil passage 13 in the camshaft 1 communicates with the clutch cover 21 on the rear side of the piston member 22, and when hydraulic pressure is applied to the clutch cover 21 from the oil passage 25, the piston member 22
2 moves forward in the direction approaching the high-speed cam 8, and when the hydraulic pressure is removed, the piston member 22 moves toward the return spring 2.
6 and retreats in a direction away from the high speed cam 8. Further, the clutch member 23 has its relative rotation with respect to the piston member 22 regulated by a clutch spring 27, and moves in accordance with one movement of the piston member 22, thereby being pressed against and separated from the high-speed cam 8. It is possible.

The pin 12 and the clutch device 20 are actuated by actuating means constituted by, for example, a hydraulic circuit 30 as shown in FIG. This hydraulic circuit 30 includes an accumulator 33 connected to an oil pump 31 via a passage 32.
And, the main oil passage 3 led out from this Aki 1 mulrator
4, an oil supply passage 35 that connects the oil passage 13 in the camshaft 1 to the main oil passage 34, a return passage 37 that connects the main oil passage 34 via a check valve 36, and the main oil passage 34. It includes a bypass passage 38 that bypasses and communicates the accumulator 33 and the oil supply passage 35, and three switching valves provided in the main oil passage 34.

The switching valve 39 is operated by an actuator 40 such as a solenoid.
Accordingly, the switch is operated to switch between the first position shown by the line '1' and the second position shown by the two-dot chain line in the figure. When the switching valve 39 is operated to the first position, the oil supply passage 3
5 and the accumulator 33 is shut off, and the oil supply passage 35 communicates with the relief passage 37.
Oil for i is supplied, but hydraulic pressure is released to the relief passage. Further, when the switching valve 39 is operated to the second position, the oil supply passage 35 is connected to the main oil passage 34.
is communicated with the accumulator 33 through the valve and is blocked from the relief passage 37, so that hydraulic pressure is sent from the accumulator 33 to the oil supply passage 35, and is transferred to the inside of the pin storage hole 11 via the oil passage 13 and the oil passage 14.25. and is supplied into the clutch cover 21. Note that the actuator 40 does not operate the switching valve 39 in a low-speed operating range where the engine speed is less than a predetermined speed.
is set to the first digit n, and the switching valve 39 is controlled by a control circuit (not shown) to be set to the second position in the high-speed operation range above a predetermined rotation speed.

According to the above-described five-actual flow control valve train, during low-speed operation, the hydraulic circuit 30 does not supply hydraulic pressure, so the pin 12 sinks into the pin storage hole 11 and the clutch The portion 4123 is mtmt from the high-speed cam 8, and the high-speed cam 8 is not connected to the camshaft 1 and the low-speed cam 7. In this state, of both cams 7.8, only the low-speed cam 7 is connected to the camshaft 1.
The valve 3 is driven by the low-speed cam 7, which rotates integrally with the low-speed cam 7, and provides valve lift characteristics suitable for low-speed operating conditions.

When in this uncoupled state, the high-speed cam 8 is biased in a direction opposite to the camshaft 1 due to the action of the needle bearing 9 provided between the high-speed cam 8 and the camshaft 1. The reverse rotation is prevented by the tappet 5. In other words, the rotation angle up to the tappet 5 in the forward rotation direction is maintained at the maximum, and the tappet 5
In the meantime, a run-up section for the aforementioned run-up rotation is secured.

When the above-mentioned low-speed operating state changes to high-speed operating state,
By switching the hydraulic circuit 30 to the hydraulic pressure supply state, hydraulic pressure is applied to the inside of the pin storage hole 11 and the clutch cover 21, respectively. After the hydraulic pressure is applied in this way, when the pin storage hole 11 is brought into alignment with the locking hole 15 due to the relative displacement of both the cams 7.8, the pin 12 pushes the receiver 16 and the locking hole 15, the high-speed cam 8 is coupled to the low-speed cam 7 and the camshaft 1, but before this coupling is achieved, the high-speed cam 8 is rotated on approach by the operation of the clutch device 20. That is, when hydraulic pressure is supplied to the clutch cover 21 of the clutch device 20, the piston member 22 slides, and the clap member 23 is pressed against the high-speed cam 8, so that the rotation of the camshaft 1 is controlled by the clutch spring 27 and the clutch. This is transmitted to the high-speed cam 8 via the frictional force of the member 23, and the high-speed cam 8 is gradually accelerated and rotates during the run-up.

This run-up rotation reduces the rotational speed difference between the low-speed cam 7 and the high-speed cam 8, and the pin storage hole 11 is connected to the locking hole 1.
5, the pin 12 is connected. Therefore, the impact applied to the pin 12 at the time of connection is alleviated, and the pin 12 smoothly moves into the locking hole 15.
This means that you will be able to enter.

After they are connected in this way, the high-speed cam 8 remains connected to the low-speed cam 7 and the camshaft 1 while maintaining a state in which the outer shape of the high-speed cam 8 includes the outer shape of the low-speed cam (see Fig. 3). By rotating together, the high-speed cam 8 substantially drives the valve 3, providing valve lift characteristics suitable for improving output during high-speed operation.

When the high speed operation state changes to the low speed operation state, the hydraulic circuit 30 is switched so that the oil pressure is divided by IJI, and the pin 12 is moved into the pin storage hole 1 by the receiver 16.
1 and detached from the locking hole 15,
When the clutch member 27 separates from the high speed cam 8, the high speed cam 8 connects the low speed cam 7 and the camshaft 1.
is switched to the unbound state.

In the above embodiment, the valve 3 is driven by the low speed cam 7.
The present invention is applied to a device configured to switch between the high-speed cam 8 and the high-speed cam 8. However, if the low-speed cam 7 is replaced with a disc-shaped member having a diameter equivalent to the base circle, the high-speed cam 8 and the high-speed cam 8 can be switched. The present invention can also be applied to a device that uses the same cam member to drive or stop the valve 3 depending on the operating state. In addition, the above-mentioned high-speed cam 8
The pin 12 that switches the high-speed cam between a coupled state and a non-coupled state with respect to the camshaft 1 may be of a type that directly engages and disengages the high-speed cam with respect to the camshaft.

Further, in the above embodiment, the valves on the cams are driven directly, but the present invention can also be applied to systems in which the valves are driven via the rocker 7-me.

(Effects of the Invention) As described above, the present invention provides a valve train 5A in which a cam member rotatably supported on a camshaft can be switched between a coupled state and a non-coupled state with respect to a cam shirt L-. A clutch device having a clutch member that can be pressed against and separated from the cam member and mounted on the camshaft, and an actuating means for the clutch device are provided, and when the clutch member is switched from the non-coupled state to the coupled state, the clutch device is attached to the camshaft. Since the cam member is rotated in the run-up by press-contacting the member to the cam member, the difference in rotational speed between the camshaft and cam member when they are connected is reduced, and the impact load applied to the pin can be reduced. At the same time, the pin connection can be performed smoothly and the reliability of the connection can be increased.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part of a valve train showing an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line ■-■ in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line ■-■ in FIG. It is a sectional view along the line. DESCRIPTION OF SYMBOLS 1... Camshaft, 3... Valve, 8... High-speed cam (cam member rotatably supported on the camshaft), 12... Pin, 20... Clutch device, 2
3...Clutch member, 30...Hydraulic circuit (operating means). Patent applicant Ntsuda stock/company agent Patent attorney Etsushi Kotani
Patent Attorney Chief 1) Masamukai Patent Attorney
Kurio Itaya Figure 2 Figure 3

Claims (1)

[Claims] 1. A cam member rotatably supported on the camshaft is provided, and a pin is provided that allows the cam member to be moved between a coupled position and a non-coupled position where the cam member rotates integrally with the camshaft. In an engine valve train that operates the pin according to a state, the pin is coupled to a clutch device that is attached to the camshaft and has a clutch member that can be pressed against and separated from the cam member. 1. A valve train for an engine, comprising: actuating means that operates to bring the clutch member into pressure contact with the cam member when the clutch member is actuated to the cam member.