JPH0751890B2 - Internal combustion engine valve operating state switching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention relates to a valve operating state for gradually changing the operating state of an intake valve or an exhaust valve according to the rotation speed of an internal combustion engine. A switching device.

<Prior Art> Conventionally, a plurality of intake valves or exhaust valves are provided for each cylinder in order to minimize intake and exhaust efficiency over a wide operating range.
In addition, various valve operating mechanisms for internal combustion engines have been proposed in which the number of operating valves is changed or the operating timing of the valves is changed according to the rotational speed of the engine. For example, JP-A-61-191111 by the applicant of the present application discloses that a low-speed cam and a high-speed cam each having a shape corresponding to the operating condition of the engine are integrated with a cam shaft, and a plurality of rocker arms slidably contacting each cam are mutually connected. Disclosed is a valve operating state switching device for an internal combustion engine, which is capable of switching between a state of relative angular displacement and a state of being integrally connected.

Connection / disconnection of the rocker arms is performed by hydraulically moving a piston that slides into a guide hole provided in each rocker arm according to the engine rotation speed. In order for the piston to move smoothly, it is necessary for both adjacent rocker arms to be in a stationary position where both rocker arms are in sliding contact with the base circle of the cam, and a timing plate that engages and disengages the expandable piston that contains the coil spring is used. A trigger means for controlling the operation timing of the piston is disclosed in, for example, Japanese Patent Application Laid-Open No. 61-61614 or Japanese Utility Model Application No. 63-79385.

However, when abnormal wear occurs on the cam slipper surface of the rocker arm, it is conceivable that the guide holes are eccentric to each other due to a change in the rocking angle of the rocker arm, which interferes with the normal operation of the piston. Therefore, the applicant of the present application has proposed a valve operating state switching device for an internal combustion engine, which is provided with a means for detecting a defective operation of a piston, as disclosed in JP-A-63-147909.

<Problems to be Solved by the Invention> However, the technique disclosed in the above publication directly detects the movement of the piston that slides into the guide hole provided in the rocker arm that swings. This is relatively troublesome, and when detecting from the hydraulic pressure, it is difficult to improve the detection accuracy because the original pressure fluctuates.

In view of such disadvantages of the prior art, the object of the present invention is to
By improving the above-mentioned conventional technology, it is possible to easily detect the operating state of the pistons in all cylinders with a relatively simple structure so as to quickly cope with abnormalities in the piston operation of the connection switching means. (EN) Provided is a valve operating state switching device for an internal combustion engine.

According to the present invention, an intake valve or an exhaust valve that is driven to open and close by a cam that rotates in synchronization with a crankshaft,
A plurality of cam followers arranged to be relatively displaceable adjacent to each other for transmitting the lift of the cam to the valve, a movable piston for selectively connecting or disconnecting the plurality of cam followers, and the piston engaged with the piston. Alternatively, a valve operating state switching device for an internal combustion engine, comprising: a connection switching means having a trigger means for disengaging and controlling the movement of the piston, wherein an operation state of the piston is detected by detecting an operation of the trigger means. This is achieved by providing a valve operating state switching device for an internal combustion engine, which is provided with a detecting means for determining.

<Operation> In this way, when connecting or disconnecting the cam follower, the piston of the connection switching means moves due to the operation of the trigger means, so the operating state of the piston is indirectly grasped from the operation of the trigger means. be able to. Since it is easy to bring the movable part of the trigger means to the outside of the cam follower, the operation detector can be relatively easily incorporated in the valve operation state switching device without complicating the structure.

<Embodiment> Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a sectional view showing a valve operating mechanism of an in-line four-cylinder engine equipped with a valve operating state switching device according to the present invention. A cam case 2 is fixed to the upper end of a cylinder head 1 fixed to the upper end of a cylinder block (not shown),
Further, a cylinder head cover 3 is fixed on it. The cylinder head 1 is provided with two intake valves 4 and two exhaust valves 5 for each cylinder.

Inside the cam case 2, intake-side and exhaust-side valve operating mechanisms 6 and 7 having the same structure are arranged in parallel and symmetrically. As will be described later, each of the valve operating mechanisms 6 and 7 is pivotally supported by three rocker arms for each cylinder adjacent to the rocker shafts 8 and 9 so as to be swingable and relatively angularly displaceable relative to each other. Camshafts 10 and 11 are rotatably supported on the.

Explaining the valve mechanism 7 on the exhaust side with reference to FIG. 2, the camshaft 11 has low-speed cams 12 and 13 having a cam profile with an oval cross section with a small lift and a cam profile with an oval cross section with a large lift. Is integrally formed with a high speed cam 14 having. The rocker shaft 9 includes two low speed rocker arms 15 and 16 corresponding to the low speed cams 12 and 13.
And corresponding to the high speed cam 14 mounted between them 1
It is provided with a high-speed rocker arm 17. Each rocker arm
On the upper surfaces of 15 to 17, cam slippers 18 to 20 which are in sliding contact with the corresponding cams 12 to 14 are formed. The cam slipper 18 of the low-speed rocker arm 15 is divided into two surfaces 18a and 18b by a deep slot 21 in a direction orthogonal to the axial direction of the rocker shaft 9.

Adjacent rocker arms 15 to 17 incorporate a connecting device 22 shown in FIG. Each rocker arm 15 to 17 swings separately during low-speed operation of the engine, but is integrally connected by a connecting device 22 to open both exhaust valves 5 during high-speed operation. The coupling device 22 comprises a trigger means consisting of a trigger member 23 for controlling its actuation timing. The trigger member 23 extends outward from a ring portion 24 fitted to the outer periphery of the low speed rocker arm 15 so as to be rotatable relative to it, and is bent in a crank shape to form a tapered trigger plate 25. And a hook 26 formed on the opposite side of the trigger plate.

As best shown in FIG. 3, the coupling device 22 has a piston that slides into a first guide hole 28 provided in one of the low speed rocker arms 15. This piston is composed of a first connecting piston 29 that engages with the rocker arm 17 for high speed and a cylindrical pressing piston 30 having a bottom, and is biased by a timing spring 31 so that they can expand and contract in the extension direction. A first groove 32 and a second groove 33 for engaging the tip of the trigger plate 25 are circumferentially provided on the outer peripheral surface of the pressing piston 30 so as to be separated from each other in the axial direction. A slot 21 is opened in the first guide hole 28, and a hydraulic chamber 34 is defined at the bottom of the slot 21.
Through the oil passage 36 provided in the rocker shaft 9. The hydraulic pressure of the coupling device 22 is supplied to the oil passage 36 from the oil pump in accordance with the rotation speed of the engine.

A second guide hole 37, which is concentric with and has the same diameter as the first guide hole 28, is formed through the high-speed rocker arm 17 at a stationary position where it is in sliding contact with the base circle of the cam 14, and the other low-speed rocker arm is inserted therein.
A second connecting piston 38 that engages 16 is slidably arranged. Similarly, the low-speed rocker arm 16 has a third guide hole.
39 is bored, and the stopper piston 40 is slidably disposed therein while being biased by the return spring 41 toward the high speed rocker arm 17 side. In the uncoupled state of FIG. 3, the rocker arms 15 to 17 are displaced relative to each other while the end faces of the spring-biased first linking piston 29 and the stopper piston 40 are in sliding contact with both end faces of the second linking piston 38. .

As best shown in conjunction with FIG. 4, the trigger member 23 is
A pin 42 fixed to the cam case 2 and a small hole 27 of the hook 26 are urged in the clockwise direction in the figure, that is, toward the rocker arm side by springs 43 having both ends engaged, and the hook 26 is fixed to the cam case 2. It is held by the stopper pin 44 which has been locked in place. Immediately below the hook 26, a well-known electromagnetic proximity sensor 45 has its detection end hooked on the hook 26.
It is fixed at a predetermined position inside the cylinder head 1 toward the lower end and with a predetermined gap. Proximity sensor
45 is electrically connected to an external control device (not shown), and outputs an OFF signal at a separated position where the hook 26 is locked by the stopper pin 44, and turns ON when the trigger member 23 is rotated and the lower end of the hook 26 approaches. Output a signal.

As shown in the figure, this valve operating mechanism has a two-stage rocker arm structure. A sub-rocker arm 46 is arranged below the low-speed rocker arm 15, and a slipper 47 on the upper surface of the sub-rocker arm 46 contacts the slipper 48 on the lower surface of the rocker arm 15. ing. The sub-rocker arm 46 has a base end 49 supported by a lash adjuster 50 fixed to the cylinder head 1, and a free end 51 closed by a valve spring 53 interposed between the retainer 52 and the cylinder head 1. It is in contact with the upper end of the valve stem 54 which is biased in the valve direction.

In the non-connected state of FIG. 3, at the stationary position where the cam slipper 18 slides on the base circle 12a of the cam 12, the low speed rocker arm 15 causes the valve spring through the sub rocker arm 46.
It is pushed up by 53 and is in the highest position. As shown in FIG. 4, the trigger plate 25 engages with the first groove 32 of the pressing piston 30 in the slot 21 to restrict its movement. As shown in FIG. 5, the low-speed rocker arm 15 has the cam 12
When the trigger member 23 is pushed down in the valve opening direction by the lift 12b, the hook 26 of the trigger member 23 is retained at the same position by the stopper pin 44, so that the trigger plate 25 and the first groove 32 are held.
The engagement with is released and the pressing piston 30 becomes movable.

Since the operating oil pressure is not supplied to the oil pressure chamber 34 during the low-speed operation of the engine, the rocker arms 15 to 17 are not coupled to each other and are relatively angularly displaced. The hydraulic pressure is supplied from the oil passage 36 to the hydraulic chamber 34 during high-speed operation of the engine.

Switching of the operation mode of the rocker arm to the high speed operation state or the low speed operation state will be described with reference to FIG. Times of Day
When the operating oil pressure is supplied to t1, the pressing piston 30 cannot move immediately because the trigger plate 25 is engaged with the first groove 32 in the stationary position shown in FIG. Time t2 after a slight time delay
When the low speed rocker arm 15 is driven in the valve opening direction, the trigger plate 25 is released from the first groove 32, but the low speed rocker arm 15 and the high speed rocker arm 17 are displaced relative to each other by the first and second positions. Since the axes of the two guide holes 28 and 37 do not coincide with each other, the first connecting piston 29 is pushed out by the pressing piston 30 and only slightly moves, and abuts on the adjacent end surface of the high speed rocker arm 17 and temporarily stops.

On the other hand, since the first groove 32 is displaced from the position of the slot 21 when the pressing piston 30 slightly moves, the trigger plate 25 contacts the outer peripheral surface of the pressing piston 30 when the low speed rocker arm 15 returns to the stationary position. It is pushed up slightly. For this reason, the hook 26 is rotated counterclockwise to the position indicated by the imaginary line 55 in the figure, and the interval with the proximity sensor 45 is narrowed. When the proximity of the hook 26 due to the lift of the trigger plate 25 is detected, the proximity sensor 45 outputs an ON signal.

When both rocker arms 15 and 17 enter the rest position shown in FIG. 4 from this state, the axes of the first guide hole 28 and the second guide hole 37 coincide with each other, so that the first connecting piston 29 becomes the second connecting piston.
While pressing 38, it slides into the second guide hole 37. At the same time, the second connecting piston 38 pushed out by the first connecting piston 29
, But pushes the stopper piston 40 and slides into the third guide hole 39.

During this time, the trigger plate 25 is lifted to the outer peripheral surface of the pressing piston 30, but when the first connecting piston 29 and the pressing piston 30 are completely moved and the second groove 33 comes to the position of the slot 21 at time t3, the spring is released. It is rotated clockwise by the urging force of 43 and engages with the second groove 26. This allows the hook 26
Returns to the original separation position, and the output of the proximity sensor 45 switches from on to off. In this way, the rocker arms 15 to 17 are connected and switched to high speed operation, and the high speed cam 14 integrally swings to open and close the intake valve and the exhaust valve.

Conversely, time t4 to switch from the high-speed operation state to the low-speed operation
When the hydraulic pressure to the hydraulic chamber 34 is released, the pistons 2930 and 38 cannot move immediately because the trigger plate 25 is engaged with the second groove 33 in the rest position shown in FIG. When the high-speed rocker arm 17 swings in the valve opening direction, the trigger plate
25 is released from the second groove 33, and the pressing piston 30 first moves to the hydraulic chamber 34 side by the urging force of the timing spring 31.
However, each connecting piston 38, 29 has a corresponding guide hole 28, 37, 39.
Due to the frictional force generated between the rocker arms 15-17 and the rocker arms 15-17, the return springs 41 return to the second guide hole 37 and the first guide hole 28 when the rocker arms 15-17 return to the stationary position.

When the rocker arms 15 to 17 come to the rest position before the pressing piston 30 moves and the first groove 32 coincides with the position of the slot 21, the trigger plate 25 causes the pressing plate 30 to move at the time t5.
It is pushed up to the outer peripheral surface and the hook 26 is rotated downward,
An ON signal is generated from the proximity sensor 45 as when switching to high-speed operation. Then, at time t6, the trigger plate 25 becomes the first
When engaged in the groove 25, the output of the proximity sensor is switched from ON to OFF again, and each rocker arm 15-17 returns to the low speed operation state in which the relative angular displacement is possible as shown in FIG.

In this way, the proximity sensor 45 generates an ON / OFF signal in response to the contact / separation operation in which the hook 26 of the trigger member 14 is lifted in a pulse shape, so that the switching state of the piston can be grasped. Also in the valve operating mechanism 6 on the air supply side, similarly, an electromagnetic proximity sensor 58 is located immediately below the hook 57 of the trigger member 56 with its detection end facing the lower end of the hook 57 and separated by a predetermined gap. It is fixed at a predetermined position in the cylinder head 1. Further, instead of the electromagnetic proximity sensor according to the present embodiment, another non-contact position sensor or a mechanical position sensor such as a limit switch can be used. Furthermore,
Although the above-mentioned embodiment relates to the valve operating mechanism of the two-stage rocker arm, the present invention can be similarly applied to the valve operating mechanism of the normal single-stage rocker arm.

FIG. 7 shows another embodiment of the present invention. In this embodiment, with respect to the four trigger members 23a to 23d of the exhaust side valve mechanism 7 arranged concentrically with the rocker shaft 9, a wire 71 made of a super elastic material is used to lock the rockers just below the hooks 26a to 26d. It is stretched in parallel with the shaft 9. Wire
In 71, the normal trigger members 23a-23d are stopper pins 44a-44d.
Both ends of the hooks 26a to 26d are fixed inside the cam case 2 by applying a certain tension so as to contact the lower ends of the hooks 26a to 26d at the stationary position.

A force sensor 72, which is a well-known load cell, is attached to one end of the wire 71. The force sensor 72 is electrically connected to an external control position (not shown).
When one of the trigger members 23 rotates during the switching operation of the piston, the wire 71 is pushed down by the hook 26 and its length is extended. The force sensor 72 detects strain generated in the length of the wire 71, converts it into an electric signal, and outputs it to the control device.

As shown in FIG. 8, when the working hydraulic pressure is supplied to the hydraulic chamber 34 of the coupling device 22 of each cylinder in the uncoupled state at time t7, the crankshaft is rotated after a slight time delay. Then, the coupling devices 22 are sequentially operated to move the pistons, and accordingly, the rotation of the trigger members 23a to 23d causes the force sensor 72 to generate four strain signals at substantially constant intervals. The control device confirms the normal operating state of the piston by counting strain signals having a level higher than a predetermined threshold value. On the contrary, when the hydraulic pressure is released from the hydraulic chambers 34 at the time t8 in the coupled state, the coupling devices 22 are sequentially operated after a slight time delay, and the force sensors 72 are rotated by the rotation of the trigger members 23. Similarly, four distortion signals are output at substantially constant intervals.

In this case, if the number of output signals is less than 4,
It is judged that an abnormality has occurred in the operation of the piston in one of the connecting devices. Furthermore, if a crank angle sensor is also used, the force sensor 72 can be used to constantly detect the rotation angle of the crankshaft.
By matching with the signal output from the cylinder, the cylinder having the piston operation abnormality can be discriminated from the order of the missing strain signals.

EFFECTS OF THE INVENTION As described above, according to the present invention, by detecting the displacement of the trigger means that controls the operation of the piston that connects or disconnects the adjacent rocker arms, the operating state of the piston can be made relatively simple. Since it can be grasped, the effect of improving the usability and reliability without complicating the structure of the valve operating state switching device of the internal combustion engine is significant.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a valve operating mechanism to which the present invention is applied. FIG. 2 is a top view showing the valve mechanism on the exhaust side. FIG. 3 is a vertical cross-sectional view of the valve switching control device of FIG. 2 in a low speed operation state as viewed from below. FIG. 4 is a view taken along the line IV-IV in FIG. FIG. 5 is a view similar to FIG. 4 when the rocker arm is swung. FIG. 6 is a diagram showing the displacement of the trigger member and the operation mode of the rocker arm due to the switching of the operating oil pressure. FIG. 7 is a perspective view schematically showing another embodiment according to the present invention. FIG. 8 is a diagram showing signals generated by wire distortion in the embodiment shown in FIG. 1 ... Cylinder head, 2 ... Cam case 3 ... Cylinder head cover 4 ... Intake valve, 5 ... Exhaust valve 6, 7 ... Valve mechanism, 8, 9 ... Rocker shaft 10, 11 ... Cam shaft 12 , 13 ...... Low speed cam 14 ...... High speed cam 15,16 ...... Low speed rocker arm 17 ...... High speed rocker arm 18 to 20 ...... Cam slipper 18a, 18b ...... Face, 21 ...... Slot 22 ...... Coupling device 23,23a to 23d …… Trigger member 24 …… Ring part, 25 …… Trigger plate 26,26a to 26d …… Hook 27 …… Small hole, 28 …… First guide hole 29 …… First connecting piston 30… … Pressing piston 31 …… Timing spring 32 …… First groove, 33 …… Second groove 34 …… Hydraulic chamber, 35 …… Passage 36 …… Oil passage, 37 …… Second guide hole 38 …… Second connection Piston 39 …… Third guide hole, 40 …… Stopper piston 41 …… Return spring 42 …… Pin, 43… … Springs 44,44a to 44d …… Stopper pin 45 …… Proximity sensor, 46 …… Sub rocker arm 47,48 …… Slippers, 49 …… Base end 50 …… Lash adjuster 51 …… Free end, 52 …… Retainer 53 …… Valve spring 54 …… Valve stem, 55 …… Imaginary line 56 …… Trigger member, 57 …… Hook 58 …… Proximity sensor, 71 …… Wire 72 …… Force sensor

Claims (1)

[Claims] 1. An intake valve or an exhaust valve that is driven to open and close by a cam that rotates in synchronization with a crankshaft, a plurality of cam followers that are arranged so as to be relatively displaceable relative to each other so as to transmit the lift of the cam to the valve, An internal combustion engine comprising: a piston movable to selectively connect or disconnect a plurality of cam followers, and a connection switching means having a trigger means for engaging or disengaging the piston to control the movement of the piston. A valve operating state switching device, comprising: detection means for detecting an operation of the trigger means to determine an operating state of the piston.