JP2641933B2 - Valve operating state switching device for internal combustion engine - Google Patents

Description

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

<Prior art> Conventionally, a plurality of intake valves or exhaust valves are provided for each cylinder in order to optimize the intake and exhaust efficiency over a wide operating range, and the number of operating valves is switched according to the engine speed. There have been proposed various valve operating mechanisms of an internal combustion engine in which the operation timing of a sliding valve is changed. For example, Japanese Patent Application Laid-Open No. 61-19911 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 low-speed operation and high-speed operation of the engine are provided on a camshaft that rotates in synchronization with the rotation of the engine. The first and second rocker arms slidingly contacting the low-speed cam and the third rocker arm slidingly contacting the high-speed cam are adjacently supported on the rocker shaft so as to be capable of relative angular displacement. A valve operating state switching device for an internal combustion engine provided with a connecting means capable of switching between a displaced state and an integrally connected state is disclosed.

The connecting means has a piston that slides into a guide hole provided inside each rocker arm, and operates the piston in a state where the base circle of the cam slides on the cam slipper surface of each rocker arm and each guide hole is aligned. To connect or disconnect the rocker arms. However, when abnormal wear occurs on the cam slipper surface of the rocker arm or the like, the swing angle of the rocker arm may change, and the guide holes may be eccentric to hinder normal operation of the piston. Accordingly, the applicant of the present application has
As disclosed in Japanese Patent No. 147909, a valve operating state switching device for an internal combustion engine including means for detecting a malfunction of a piston has been proposed.

<Problems to be Solved by the Invention> However, in a low-temperature state such as during engine start or cold when the fluidity of the lubricating oil (the operating oil of the connecting means) generally decreases, the above-described piston operation failure detection system malfunctions. May occur.

The present invention has been devised in order to improve such inconvenience, and a main object of the present invention is to provide a valve operating state switching device for an internal combustion engine which is improved so as not to cause a malfunction in a low temperature state. To provide.

[Constitution of the Invention] <Means for Solving the Problems> According to the present invention, the above-described object is to provide a camshaft integrally having a cam and rotating synchronously with a crankshaft, and a spring having a spring in a normally closed direction. An intake valve or an exhaust valve urged to open the valve by the cam; a plurality of cam followers disposed adjacent to each other so as to be displaceable from each other so as to impart a lift of the cam to the valve; and a cam follower provided inside the cam follower. Connection switching means having a plurality of pistons slidingly connected to the guide holes and reciprocally driven by an external force to connect or disconnect between the cam followers, and a fluid passage communicating the pressure fluid source with the inside of the engine via the guide holes Detecting means for detecting the operating position of the piston by detecting the pressure or flow rate of the fluid in Temperature of the fluid is the detection means only when the predetermined value or more is achieved by providing a valve operating state changing device for an internal combustion engine, characterized by operating to be.

<Operation> In this way, each piston engages at a predetermined operating position across the guide holes of the adjacent cam followers, and each cam follower operates simultaneously, and each piston guides the corresponding cam follower. In the non-connection state in which the respective cam followers slide relative to each other in the hole, the flow rate or the pressure of the fluid for driving the piston changes, and the operating position of the piston is detected from the degree of the change. Then, it is estimated whether or not the fluidity of the fluid is normal from the temperature of the fluid, and only when it is estimated that the fluidity is normal, the operation position of the piston is detected.

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

As shown in FIG. 1, a pair of intake valves 1a and 1b provided in the internal combustion engine main body are integrally provided on a camshaft 2 which is synchronously driven at half the speed of a crankshaft (not shown). Opening / closing operation is performed by a pair of low-speed cams 3a and 3b having a cross section and a single high-speed cam 4 and first to third rocker arms 5 to 7 as cam followers that slidably contact with these cams and swing. . Further, the engine includes a pair of exhaust valves (not shown) that are driven to open and close similarly to the above-described intake valves 1a and 1b.

The first to third rocker arms 5 to 7 are swingably supported adjacent to each other on a rocker shaft 8 which is provided under and parallel to the camshaft 2. The first and third rocker arms 5, 7 have basically the same shape, the base of which is pivotally supported by the rocker shaft 8, and the free ends thereof are the intake valves 1a, 1b.
Extending upward. At the free ends of the two rocker arms 5 and 7, tappet screws 9 abutting on the upper ends of the intake valves 1a and 1b are provided.
a and 9b are screwed so as to be able to advance and retreat, respectively, and are locked by lock nuts 10a and 10b. Cam slippers 5a and 7a are formed on the upper surfaces of the central portions of the rocker arms 5 and 7 to be in sliding contact with the low speed cams 3a and 3b, respectively.

The base of the second rocker arm 6 is supported by a rocker shaft 8 between the first and third rocker arms 5 and 7. The free end of the second rocker arm 6 is a rocker shaft 8.
From the intake valves 1a and 1b, a cam slipper 6a is formed on the upper surface thereof for sliding contact with the high-speed cam, and a lifter (not shown) fixed to the cylinder head side is formed on the lower surface. ) Is in contact with the upper end surface. The lifter always urges the second rocker arm 6 upward as a lost motion spring so that the cam slipper 6a always comes into sliding contact with the high-speed cam 4.

The camshaft 2, which is rotatably supported above the engine body,
Low-speed cams corresponding to the first and third rocker arms 5 and 7
3a, 3b and a high-speed cam 4 corresponding to the second rocker arm 6 are integrally connected. 2, the low-speed cams 3a, 3b have a relatively small head and are formed in a cam profile suitable for the low-speed operation of the engine, and the first and third rocker arms 5, 3 respectively. 7 comes into sliding contact with the cam slippers 5a and 7b. The high-speed cam has a larger head over a wider angle than the low-speed cams 3a and 3b,
Further, the cam profile is formed in a cam profile suitable for high-speed operation, and slides on the cam slipper 6a of the second rocker arm 6.

The first to third rocker arms 5 to 7 can be switched between a state in which they can swing integrally and a state in which they can be relatively displaced by a connecting device 11 provided at the center thereof. A valve spring 13 is provided above the intake valves 1a and 1b, and is provided between the engine body so as to surround the stems of the intake valves 1a and 1b.
A and 13b urge both valves 1a and 1b in the valve closing direction, that is, upward in FIG.

As shown in FIG. 3, the first rocker arm 5 is provided with a first guide hole 14 opened toward the second rocker arm 6 in parallel with the rocker shaft 8. First
At the bottom side of the guide hole 14, a small diameter portion 15 and a cut
Are formed. The second rocker arm 6 has a second guide hole communicating with the first guide hole 14 of the first rocker arm 5.
17 are penetrated. The third rocker arm 7 is provided with a third guide hole 18 communicating with the second guide hole 17.
A small-diameter through hole 19 is formed at the bottom of the third guide hole 18 concentrically with the third guide hole 18.

A first piston 21, a second piston 22, and a stopper 23 are slid on the first to third guide holes 14, 17, and 18, respectively. The stopper 23 is urged by the compression coil spring 24 toward the first and second rocker arms 5 and 6 to restrict the movement of the pistons 21 and 22. The first piston 21 has an axial length such that one end thereof abuts the step 16 of the first guide hole 14 and the other end does not project from the first guide hole 14. The second piston 22 has the same axial length as the second guide hole 17.

A hydraulic chamber 25 is defined between the bottom of the first guide hole 14 and the end surface of the first piston 21. On the other hand, a pair of passages 26 and 27 connected to a hydraulic supply device described later are formed in the rocker shaft 8. The one passage 26 communicates with the hydraulic chamber 25 via a communication hole 28 formed in the peripheral wall of the rocker shaft 8 and a communication passage 29 provided in the first rocker arm 5. From this hydraulic oil supply passage 26, the first rocker arm 5
The hydraulic oil is always introduced into the hydraulic chamber 25 irrespective of the rocking state of the hydraulic fluid.

The first rocker arm 5 has a first oil passage 32 connected to a communication hole 31 formed in a peripheral wall of the rocker shaft 8 and opened to the inner peripheral surface of the first guide hole 14, and an inner peripheral surface of the first guide hole 14. And a second oil passage 33 which is opened at the same axial position as the first oil passage 32 and is opened inside the engine. On the other hand, on the outer peripheral surface of the first piston 21, an annular groove 34 communicating the oil passages 32 and 33 at the third illustrated position where the one end contacts the step portion 16 is provided. Therefore, at this piston position, the lubricating oil passage 27 communicates with the inside of the engine via the communication hole 31, the two oil passages 32, 33 and the annular groove.

Similarly, the third rocker arm 7 is connected to a communication hole 35 formed in the peripheral wall of the rocker shaft and has a third guide hole.
A first oil passage 36 that opens on the inner peripheral surface of the 18 and a second oil passage 37 that opens at the same axial position as the first oil passage 36 on the inner peripheral surface of the third guide hole 18 and that is open inside the engine. It is installed inside. On the other hand,
On the outer peripheral surface of the stopper 24, an annular groove 39 communicating with the first oil passage 36 and the second oil passage 37 at a position shown in FIG. Therefore, at this stopper position, the lubricating oil passage 27 communicates with the inside of the engine via the communication hole 35, the two oil passages 36 and 37, and the annular groove 38.

The lubricating oil stored in the oil pan 41 is supplied at a predetermined pressure by, for example, a lubricating oil pump 42 connected to the crankshaft of the engine, and is branched on the way and one of the lubricating oil is supplied via a solenoid valve 43. The other is supplied to the passage 26 and the lubricating oil passage 27. A hydraulic pressure sensor 44 is provided at the downstream end of the lubricating oil passage 27 so that the oil pressure in the passage 27 can be constantly monitored.

Next, the operation of the above-described embodiment will be described with reference to FIGS.

In the middle and low speed range of the engine, the solenoid valve 43 is closed.
No hydraulic pressure is supplied to the hydraulic chamber 25 of the coupling device 11. Accordingly, since the pistons 21 and 22 are located in the guide holes 14 and 17 as shown in FIG. 3 by the urging force of the compression coil spring 24, the rocker arms 5 to 7 can be displaced relative to each other. In the unconnected state of the connecting device 11, the rotation of the camshaft 2 causes the first and third rocker arms 5,
7 slidably contacts the low speed cams 3a and 3b and swings to open and close the intake valves 1a and 1b. In this case, the second rocker arm 6 slidably contacts the high-speed cam 6 and swings.
It has no effect on the operation of 1a and 1b.

On the other hand, the lubricating oil is always fed under pressure to the lubricating oil passage 27, and lubricates between the rocker shaft 8 and each of the rocker arms 5 to 7 via an oil hole (not shown).
Through each of the second oil passages of the first and third rocker arms 5, 7
It is discharged into the engine from 33 and 37. Therefore, in this state, the command pressure P1 of the oil pressure sensor 44 indicates a low value. The lubricating oil discharged into the engine is used to lubricate the sliding surfaces of the cams. In this way, effective use can be achieved without increasing the amount of lubricating oil for the engine.

During high-speed operation of the engine, the operating oil pressure is supplied from the operating oil supply passage 26 to the hydraulic chamber 25 through the communication hole 28 and the communication passage 29 by opening the electromagnetic valve 43. Thereby, as shown in FIG. 4, the first piston 21 moves toward the second rocker arm 6 against the urging force of the spring 24 until the stopper 23 contacts the bottom of the third guide hole 18, and The second piston 22 is pushed by the first piston 21 and moves to the third rocker arm 7 side. In this way, the first piston 21
The second rocker arms 5 and 6 are connected to the second and third rocker arms 6 and 7 by the second piston.
In such a connected state, the second sliding contact with the high-speed cam 4
Since the rocking amount of the rocker arm 6 is the largest, the first and third rocker arms 5 and 7 rock together with the second rocker arm 6 to open and close both intake valves 1a and 1b according to the cam profile of the high-speed cam 4.

By the movement of the first piston 21 and the stopper 23, the first oil passages 32, 36 of the first and third rocker arms 5, 7 are closed, respectively. Therefore, the lubricating oil flowing through the lubricating oil passage 27 is supplied between the rocker arms 5 to 7 and the rocker shaft 8 and leaks only from between the pistons 21 and 22 and the stopper 23 and the guide holes 14, 17 and 18. . For this reason,
In the connected state, compared to the unconnected state in which the lubricating oil is discharged from the two oil passages 32, 36, the oil pressure sensor 44 shows a considerably high pressure.

At this time, if there is a malfunction in each of the pistons 21, 22 and the stopper 23, the first oil passages 32, 36 remain open, so that the lubricating oil flowing through the lubricating oil passage 27 , 36,
It is discharged into the engine from 37. Therefore, the operation pressure can be immediately recognized because the command pressure of the oil pressure sensor 44 does not increase. Further, since there is a considerable pressure difference between the non-coupled state and the coupled state, even if a malfunction of the piston occurs in some cylinders of the engine, the pressure and the flow rate in the lubricating oil passage 27 change proportionally. Therefore, the number and the state of the inoperative pistons can be known from the change rate of one hydraulic pressure sensor 44. Further, in this embodiment, since the above-described connecting devices are separately provided on the intake side and the exhaust side of each cylinder, malfunctions of the pistons can be separately detected on the intake side and the exhaust side. .

The operation on the return side of the two pistons 21 and 22 from the connected state to the unconnected state does not need to be particularly detected because it is relatively reliable, but if at least one piston is in the connected state during low-speed operation, Since the pressure in the lubricating oil passage 27 increases by that amount, the operation of both pistons in both directions can be detected. Further, it is conceivable that the piston does not operate due to a malfunction of the solenoid valve 43, but this can be detected by monitoring the hydraulic pressure of the hydraulic oil supply passage 26 by a separate hydraulic sensor.

Further, since the lubricating oil generally has poor fluidity in a low temperature state such as when the engine is started or when it is cold, in the above-described detection system for malfunction of the piston, the lubricating oil temperature is set to a certain value in order to prevent the malfunction. It will not be activated until it reaches a certain level.

The driving means for switching the piston may be an electric or mechanical device instead of a hydraulic type. Further, the rocker arm may be a center pivot type, and the transmission member may be a direct type bucket lifter.
Further, the opening positions of the respective oil passages are not limited to those in the above-described embodiment, and may be configured to be closed in a non-connected state and opened in a connected state. Further, the oil passage opened from the lubricating oil passage into the engine is provided in the first and third rocker arms.
And the second and third rocker arms, or the second and third rocker arms, and all of the first to third rocker arms may be provided with an oil passage. Also in this case, the operating state of the piston can be detected by one hydraulic sensor provided at the downstream end of the lubricating oil passage.

[Effects of the Invention] As described above, according to the present invention, the malfunction detection system is not operated in a low temperature state in which the fluidity of the hydraulic oil driving the connecting device is reduced, so that malfunction can be prevented, A great effect is obtained in improving the usability and reliability of the valve operating state switching device of the internal combustion engine.

[Brief description of the drawings]

FIG. 1 is a top view of a valve operating mechanism having a valve operating state switching device to which the present invention is applied. FIG. 2 is a view as seen from an arrow II in FIG. FIG. 3 is a sectional view taken along line III-III in FIG. 2 in a low-speed operation state. FIG. 4 is a sectional view similar to FIG. 3 in a high-speed operation state. 1a, 1b ... intake valve, 2 ... cam shaft 3a, 3b ... low speed cam 4 ... high speed cam, 5 ... first rocker arm 6 ... second rocker arm, 7 ... third rocker arm 5a to 7a ... Cam slipper 8 ... Rocker shaft, 9a, 9b ... Tappet screw 10a, 10b ... Lock nut 11 ... Connecting device, 12a12b ... Retainer 13a, 13b ... Valve spring 14 ... First guide hole, 15 …… Small diameter part 16 …… Step part, 17 …… Second guide hole 18 …… Third guide hole, 19 …… Through hole 21 …… First piston, 22 …… Second piston 23 …… Stopper, 24… … Compression coil spring 25… Hydraulic chamber, 26… Hydraulic oil supply passage 27… Lubricating oil passage, 28… Communication hole 29… Communication passage, 31… Communication hole 32… First oil passage, 33… … Second oil passage 34 …… Circular groove, 35 …… Communication hole 36 …… First oil passage, 37 …… Second oil passage 38 …… Circular groove, 41 …… Oil pan 42 …… Hydraulic pump, 43 …… Solenoid valve 44 …… Hydraulic sensor

Claims (1)

(57) [Claims] A camshaft integrally having a cam and rotating synchronously with a crankshaft; an intake valve or an exhaust valve which is normally biased in a valve closing direction and is driven to open by said cam; A plurality of cam followers arranged adjacent to each other so as to be able to relatively displace each other so as to impart a lift to the valve, and are slid into guide holes provided in the cam followers and reciprocally driven by an external force to connect or connect the cam followers. Detecting the operating position of the piston by detecting the pressure or flow rate of fluid in a fluid passage communicating between the pressure fluid source and the inside of the engine via the guide hole and the connection switching means having a plurality of pistons to be released; A valve operating state switching device for an internal combustion engine, comprising: a detecting unit that operates when the temperature of the fluid supplied to the fluid passage is equal to or higher than a predetermined value. A valve operating state switching device for an internal combustion engine.