JP2004156627A5 - - Google Patents

Description

Engine valve actuator

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine valve operating device, and more particularly to an engine valve operating device in which valve lift characteristics are switched between a low engine speed and a high engine speed.

  Conventionally, in order to achieve both high torque characteristics during low-medium speed operation and improved output during high-speed operation, the intake valve or exhaust valve lift characteristics are made different according to the operating conditions, which enables the intake and exhaust timing. Alternatively, it is known to control the intake / exhaust amount (see Patent Documents 1 and 2).

  In these, a low-speed rocker arm whose rocking tip abuts on the valve and a high-speed rocker arm that is a free cam follower provided between the low-speed rocker arm and not having a contact portion with the valve swing on a common rocker shaft. The low-speed rocker arm is slidably contacted with the low-speed cam, and the high-speed rocker arm is slidably contacted with the high-speed cam having a profile in which the valve opening angle or the valve lift amount is larger than that of the low-speed cam. .

The high-speed rocker arm and the low-speed rocker arm are each formed with a fitting hole in a direction parallel to the rocker shaft at a swinging portion that is separated from the rocker shaft by a predetermined distance. Is connected to the three rocker arms, or the connection is released when the plunger is fitted in the fitting hole in response to the hydraulic pressure or is pulled out of the fitting hole. A mechanism is provided.
JP-A 63-167016 JP-A 63-57805

However, in such a conventional valve operating device, the sub-rocker arm for the high-speed cam follower attached to the main rocker arm is connected to or disconnected from the main rocker arm, and the valve lift characteristics at low speed and high speed However, there is play in the connecting portion due to variations in dimensional accuracy, etc., and for this reason , a gap may occur in the connecting portion between the sub-rocker arm and the main rocker arm . Therefore, when the lift via the connecting portion from the sub-rocker arm to the main rocker arm is transmitted by the high-speed cam, impact load is applied to the abutting portion of the consolidated portion, giving abnormal wear, jump during opening and closing operation of the valve There is a risk that abnormal movement such as

  An object of the present invention is to focus on the above-mentioned problem, and to solve the problem, when the second rocker arm driven by the second cam and the first rocker arm linked to the intake / exhaust valve are coupled, they are coupled. Providing a valve operating device for an engine that prevents the occurrence of gaps in the engaging portion, prevents the occurrence of abnormal operation by allowing the input load for stable valve lift to be transmitted from the cam to the valve at all times. There is to do.

In order to achieve such an object, the present invention provides a first rocker arm that is swingably supported by a rocker shaft and whose tip is linked to an intake valve or an exhaust valve and is driven by a first cam; A second rocker arm supported by the rocker arm and biased toward the second cam by a spring acting between the first rocker arm and driven by the second cam ; and supported by the first rocker arm ; and coupling the switching member movable between an engaged position and a disengaged position to a non-coupling state of the second rocker arm to the coupling with said first rocker arm, the said coupling switching member disengaged position side a second spring for biasing f, formed through the rocker shaft, provided with an oil passage for supplying hydraulic pressure for moving said coupling switching member to the engaging position, When the coupling switching member is in the non-engagement position, a gap is maintained between the basic circular portion of the second cam and the second rocker arm, and the coupling switching member is in the engagement position. The relative positions of the engaging portions are set so that the coupling switching member engages the second rocker arm while pushing the second rocker arm toward the second cam by the hydraulic pressure when moving to It is characterized by being.

When hydraulic pressure is supplied from the oil passage, the coupling switching member moves from the non-engagement position to the engagement position and engages with the second rocker arm. As a result, the second rocker arm is coupled to the first rocker arm. Here, when the coupling switching member moves to the engagement position, the coupling switching member engages with the second rocker arm while pushing up the second rocker arm toward the second cam by the hydraulic pressure. Accordingly, there is no gap between the coupling switching member and the second rocker arm.

According to the present invention, when the coupling switching member moves from the non-engagement position to the engagement position by hydraulic pressure, the coupling switching member engages with the second rocker arm while pushing up the second rocker arm to the second cam side. In the coupled state between the first rocker arm and the second rocker arm, there is no gap between the coupling switching member and the second rocker arm. Accordingly, transmission is rather name that cam input load transmitted from the second cam to the second rocker arm acts between the coupling switching member and the second rocker arm becomes impact load, a constantly stable cam input load to the valve it becomes possible to, also, to prevent the occurrence of abnormal wear and tapping sound of the engaging portions of the coupling switching member and the second rocker arm, it can contribute to the prevention of abnormal valve lift operation.

  Hereinafter, embodiments of the present invention will be described in detail and specifically based on the drawings.

  1 to 5 show an embodiment of the present invention.

  In this example, the present invention is applied to an engine having two valves (both an intake valve and an exhaust valve, and the illustrated one is an intake valve) having the same function for one cylinder. The example of this is shown. That is, each cylinder is provided with a single main rocker arm (first rocker arm) 1 corresponding to two intake valves 2, and the base end of the main rocker arm 1 is a hollow main rocker shaft 3 common to each cylinder. And a bifurcated tip portion 1A of the main rocker arm 1 abuts on the stem top portion of the intake valve 2.

  The main rocker arm 1 is formed in a bifurcated shape in a plan view, and a low-speed cam follower 4 is provided substantially above the center of each arm portion 1E, 1E formed in the bifurcated portion of the main rocker arm 1.

  Reference numeral 5 denotes a sub rocker arm (second rocker arm) that is swingably supported by a support shaft 6 above the crotch portion formed at the fork of the main rocker arm 1, and 7 is a high-speed cam follower provided at the end of the sub rocker arm 5. is there. The high-speed cam follower 7 and the two low-speed cam followers 4 are arranged in the axial direction of the cam shaft 8 as shown in FIGS. Reference numerals 9 and 10 denote a high-speed cam (second cam) and a low-speed cam (first cam) formed integrally with the cam shaft 8. The high-speed cam follower 7 and the low-speed cam follower 4 described above are connected to the high-speed cam 9 and the low-speed cam 10. Each is driven by sliding contact.

  Next, the high / low speed switching mechanism according to the present invention will be described with reference to FIGS.

  4A, 4B, and 5 show a low-speed operation state, and FIG. 4C shows a high-speed operation state. In FIG. 4, 5B is a first plunger housing hole drilled in the sub rocker arm 5, 1B is a second plunger housing hole drilled in the main rocker arm 1, and 1C shown in FIG. It is the 3rd plunger accommodation hole drilled in. 21 is a first plunger that is slidably fitted in the first plunger housing hole 5B, 22 is a spring that biases the tip of the first plunger 21 toward the abutting portion 1D of the main rocker arm 1, and 23 is A stopper ring 24 that regulates the stroke of the first plunger 21 is an air vent.

On the other hand, an oil passage 25 for guiding oil from an oil passage 3A provided at the center of the rocker shaft 3 is communicated with the second plunger housing hole 1B, and the second plunger housing hole 1B is slidably kept in the housing hole 1B. Plunger 26 is inserted. A lever member 11 is supported on the main rocker arm 1 so as to be swingable on a lever support shaft 12. Reference numeral 13 denotes an engaging end provided at one end of the lever member 11, and 11 B denotes an operating end that contacts the second plunger 26. 4B, 27 is a third plunger that is slidably held in the third plunger housing hole 1C, and 28 is directed to a protrusion 11A (see FIG. 1) provided with the third plunger 27 on the lever member 11. The spring is biased. In the low speed operation state as shown in FIG. 5A, the clearance S is maintained between the basic circle portion 9A of the high speed cam 9 and the high speed cam follower 7. . This clearance S is set to such an extent that the engagement end 13 of the lever member 11 can push up the sub rocker arm 5 even when the base circle portion 9A of the high speed cam 9 is opposed to the high speed cam follower 7. Further, the engaging portion 13 of the sub rocker arm 5 pushes up the sub rocker arm 5 by the engaging end 13 when both engage with the engaging end 13 of the lever member 11 as shown in FIG. feeling is set to be operated, further corners of both chamfer of the chamfered or curved plane so that the operation can be performed smoothly is applied.

  Next, the valve operation during high speed operation and low speed operation according to this embodiment will be described with reference to FIGS. 4A to 4C and FIGS. 5A and 5B.

  Now, when it is in the state of low speed operation as shown in FIG. 5A or FIG. 4A, the hydraulic pressure is supplied to the second plunger 26 through the oil passage 3A of the rocker shaft 3. The lever member 11 is rotated clockwise by the third plunger biased by the spring 28 as shown in FIG. 4B, and the locking portion 5A of the sub rocker arm 5 and the lever member 11 are The engagement end 13 is kept in the non-engaged position. Thus, the sub rocker arm 5 is allowed to swing with respect to the main rocker arm 1. Even if the high speed cam 9 is in sliding contact with the high speed cam follower 7 in FIG. The lift by the high-speed cam 9 is not transmitted to the valve shaft 2A simply by absorbing the cam profile, while the low-speed cam 10 is in sliding contact with the low-speed cam follower 4 so that the valve shaft 2A of the valve 2 is lifted by the lift by the low-speed cam 10. Operate.

  Further, during high-speed operation, a hydraulic pressure is supplied to the oil passage 3A by a control unit (not shown) via the hydraulic pressure supply means, and the second plunger 26 is accommodated in the second plunger 26 as shown in FIG. By projecting from the chamber 1B and pressing the operating end 11B of the lever member 11, the lever member 11 is rotated counterclockwise. In this case, the lever member 11 operates to push the third plunger 27 back into the third plunger housing hole 1C against the spring force of the spring 28, and the engagement as shown in FIG. The joint end 13 is engaged with the locking end 5 </ b> A so as to push up the sub rocker arm 5. Such push-up is possible by the gap S described above.

  Thus, during the switching operation from the low speed rotation to the high speed rotation, there is no gap between the engaging end 5A of the sub rocker arm 5 and the engaging end 13 of the lever member 11, so that the engagement of the sub rocker arm 5 is not caused. The stop end 5A and the engagement end 13 of the lever member 11 are always kept in contact. Therefore, even when the lift of the high-speed cam 9 is started during the transition of the switching operation, the engaging end 5A of the sub rocker arm 5 does not collide with the engaging end 13 of the lever member 11, and the engaging end 13 of the lever member 11 is It is possible to prevent an impact load from being received in advance, to prevent occurrence of abnormal wear or hitting sound between both sliding contact portions, and to prevent abnormal operation of the valve lift.

  Further, at the time of switching from the high speed rotation to the low speed rotation, the hydraulic pressure supplied to the oil passage 3A is stopped, and the third plunger 27 rotates the lever member 11 in the clockwise direction by the spring force of the spring 28. . Therefore, the engaging end 13 of the lever member 11 is pulled off from the engaging end 5A of the sub rocker arm 5, and a low speed operation state as shown in FIG.

  In the embodiment described above, the example is applied to an engine having two valves having the same function in one cylinder. However, the application of the present invention is not limited to such an engine. Needless to say, for example, the present invention can be applied to an engine in which one cylinder is provided with one intake valve and one exhaust valve.

It is a side view which shows the structure of one Example of this invention. It is a top view except the cam apparatus of the Example shown in FIG. It is a front view of the Example shown in FIG. The valve operating state at the time of low lift according to the embodiment shown in FIG. 1 is shown in the sectional view taken along line AA in FIG. 2 and the sectional view taken along line BB in FIG. FIG. 3 is an explanatory view showing a cross-sectional view taken along line AA in FIG. 2 (C). It is explanatory drawing which shows the valve operating state at the time of the low lift of the Example shown in FIG. 1 with the state figure (A) and the enlarged view (B) of P part of a figure (A).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main rocker arm 1A (arm) front-end | tip part 1B 2nd plunger accommodation hole 1C 3rd plunger accommodation hole 1D Abutting part 1E Arm part 2 (Intake) valve 3 Rocker shaft 3A Oil path 4 Low speed cam follower 5 Sub rocker arm 5A Locking part 6 Support shaft 7 High-speed cam follower 8 Cam shaft 9 High-speed cam 10 Low-speed cam 11 Lever member 11A Protrusion 11B Operating end 12 Lever support shaft 13 Engagement end 21 First plunger 22, 28 Spring 25 Oil passage 26 Second plunger 27 Third plunger S gap

Claims (3)

A first rocker arm that is swingably supported by the rocker shaft and whose tip is linked to an intake valve or an exhaust valve and is driven by a first cam;
A second rocker arm supported by the first rocker arm and biased toward the second cam by a spring acting between the first rocker arm and driven by the second cam;
Is supported by the first rocker arm, and a coupling switching member movable between an engaged position and a disengaged position to a non-coupling state of the second rocker arm to the coupling with said first rocker arm,
A second spring that biases the coupling switching member toward the non-engagement position;
An oil passage formed through the rocker shaft for supplying hydraulic pressure for moving the coupling switching member to the engagement position;
Comprising
When the coupling switching member is in the non-engagement position, a gap is maintained between the basic circular portion of the second cam and the second rocker arm,
When the coupling switching member moves to the engagement position, the coupling switching member engages with the second rocker arm while pushing the second rocker arm toward the second cam by the hydraulic pressure. A valve operating device for an engine, wherein a relative position of the joint is set . 2. The valve operating device for an engine according to claim 1, wherein chamfering is applied to each corner portion of the engaging portions engaged with each other. 3. The engine valve operating device according to claim 1, further comprising a stopper for restricting the movement of the second rocker arm by the spring in order to secure the gap.