JPS6027801B2 - variable valve lift engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable valve lift engine, and more particularly to a variable valve lift engine for an internal combustion engine in which the opening/closing conditions of intake valves, exhaust valves, etc. of the internal combustion engine are made variable according to engine operating characteristics. Concerning the disguise.

As a matter of fact, the engine characteristics of an internal combustion engine are generally influenced by the cam characteristics.

For example, if the cam shape is selected to produce high torque at low rotations, the torque at high rotations will be sacrificed, and conversely, if the cam shape is selected to produce high torque at high rotations, the torque at low rotations will be sacrificed, and the conventional With internal combustion engines, it is difficult to maintain high output and high performance over almost all operating ranges, from low rotation speeds to high rotation speeds. In order to maintain high output and high performance over almost the entire engine speed range from low speed to high speed, the valve lift of the engine open/close valve is variable according to the engine operating characteristics, and the structure is simple and the operating cam conditions can be changed. The applicant has previously proposed the following engine as a variable valve lift engine in which the valve lift can be performed at any cam position, that is, at either the base circle portion or the working stroke portion of the cam.

A three-dimensional cam having a cam surface that changes continuously in the axial direction of the camshaft is installed on a camshaft that rotates in synchronization with the engine's crankshaft, and the engine is mounted on a rocker ball installed parallel to the camshaft. This is a variable valve lift engine in which a rocker arm that opens and closes an on-off valve is pivotally connected, and the cam ball and rocker arm are movable relative to each other in the direction of the rocker axis. However, this engine has a problem in that wear and pitching are likely to occur at the contact portion between the rocker arm and the cam surface. In the present invention, the above problem is solved by rotatably supporting a roller on the cam contact portion of the rocker arm, and making the cross section of the roller in the axial direction of the rocker arc shaped. Further, in the present invention, the rocker arm and the on-off valve, especially the valve spring retainer fixed to the upper end thereof, are connected by a spring, preferably a leaf spring in the shape of a figure 5, to constantly press the roller against the cam surface. This prevents the roller from slipping and wearing when it comes into contact with the cam surface again after it separates from the cam surface and idles.
Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, a cylinder bore (not shown) is bored in the cylinder block, and a cylinder head 3 with a combustion chamber wall 3a bored therein is fixed on the cylinder head. A piston (not shown) is reciprocatably and slidably assembled in a sealed formation within the cylinder bore to form a combustion chamber 7 surrounded by the cylinder bore, the combustion chamber wall 3a, and the upper surface of the piston. An intake boat 9 formed in the cylinder head 3 is passed through the combustion chamber 7 via an intake valve 11 to control the intake of the intake air-fuel mixture. Similarly, an exhaust boat formed on the cylinder head 3 is passed through the combustion chamber 7 via an exhaust valve (both not shown) to control exhaust discharge. Intake valve 1
Since the structures of the intake valve 1 and the exhaust valve are similar, the intake valve 11 will be described below. The intake valve 11 includes a valve body 11a and a valve rod 11b protruding from the valve body 11a.

The valve body 11a cooperates with a valve seat 9a formed at a portion where the intake boat 9 closes to the combustion chamber 7 to close the combustion chamber 7 from the intake boat 9.
Change the intake passage area. The valve rod 11b is slidably and sealed in a mounting hole 3b formed in the cylinder head 3, and a retainer 1 is attached to the upper end of the part protruding from the cylinder head 3.
3 is fixed. A compression spring 15 is installed between the retainer 13 and the upper surface of the cylinder head 3 to urge the intake valve 11 upward and seat the valve body 11a on the valve seat ga. A rocker shaft 21 is fixedly installed along the longitudinal direction of the engine, and a rocker arm 19 is pivotally connected to the rocker shaft 21 so as to be swingable around the rocker shaft 21.

A knocker 25 is screwed onto the tip 19a of the rocker arm 19, and its length can be adjusted using a lock nut 23. As shown in FIG. 2, the other half 19b of the rocker arm 19 has a substantially horizontal surface and is shaped like a fork, and rotatably supports the roller 27 in the gap between both forks. That is, the pin 29 inserted into the hole 4 bored in the fork is passed through a support hole (not shown) formed in the center of the roller 27. It is preferable to provide a metal bearing or a rolling bearing between the pin 29 and the support hole. As shown in FIG. 2, the cross-sectional shape of the roller 27 in the direction of the rocker shaft 21 is formed into an arc shape with a radius of curvature R. A cam shaft 31 is rotatably mounted on a crankshaft (not shown) of an engine parallel to the rocker shaft 21.

A spline groove 31a is formed on the camshaft 31, and the cam 33 can be moved in the direction of the camshaft 31 by the spline groove 31a. The cam 33 has a cam surface that changes three-dimensionally. That is, for example, the end surfaces 33a, 3 of the cam surface are aligned in the rutting direction.
3b, and the conical surface is changed in all directions around the axis of the camshaft 31 to continuously change three-dimensionally. A cylindrical protrusion 33c is formed at one end of the cam 33, and an annular groove 33d is formed in the protrusion 33c. A fluid pressure cylinder 35 or a motor and a cam mechanism (
A cam moving mechanism such as (not shown) is provided to enable the piston 35a of the fluid pressure cylinder 35 to move along the camshaft 31, and a pin 37 that engages with the annular groove 33d is fixed to the top of the piston 35a. . When the fluid pressure cylinder 35 is actuated to move the piston 35a, the piston 37 also moves, thereby causing the cam 33 to move toward the camshaft 3.
Move up by 1. Rocker arm 1 is attached to the cam surface of cam 33.
9 is brought into contact with the roller 27. A spring 41 is provided between the rocker arm 19 and the valve retainer 13 to connect the rocker arm 19 and the IJ retainer 13. The spring 41 is a plate spring made of spring steel, and has an upper portion wound around the front end of the rocker arm 19 and a lower portion shaped like a horizontal U, as shown in FIG. Attach the U-shaped lower part to the retainer 13
The rocker arm 19 and the retainer 13 are urged by the elasticity of the U-shaped portion of the spring 41. As a result, the roller 27 is always pressed against the cam surface of the cam 33 and no gap is created between the cam and the roller, so that the roller is prevented from moving violently when such a gap is formed and violently colliding when the next roller contacts. Moreover, since the spring 41 is supported by the rocker arm 19 and moves together with the rocker arm 19, the displacement of the spring 41 hardly changes during the rotation of the cam 33. Therefore, the constant load used to open and close the valve by the compression spring 15 is normally set in advance. It is only necessary to consider the biasing force of the leaf spring 41, which is the number X9. Further, as shown in FIG. 3, one end of the spring 41 is wound around the rocker arm 19 so as to be in close contact with the upper surface, right side surface, and lower surface of the rocker arm 19, and to be latched to the upper end of the left side surface. It can be attached to and detached from the rocker arm 19 from the right side. That is, the spring 41 can be attached to and detached from the rocker arm 19 by exposing one end thereof, and in this case, there is no need to remove other parts. In the above description, the structure in which the cam 33 is moved along the cam shaft 31 has been described, but in the present invention, the rocker arm 19 may be moved along the rocker shaft 21 instead of moving the cam 33.

In this case, the rocker arm 19 is supported so as to be movable along the rocker shaft and swingable around the rocker shaft,
A rocker arm movement mechanism (not shown) similar to the cam movement mechanism described above is provided. The rocker arm is moved along the rocker axis. Additionally, as the rocker arm 19 moves, the knocker 25 moves, making it impossible to open or close the intake valve 11. Therefore, the rocker arm 19 must be placed so that a valve lifter can be placed over the intake valve 11, or the head of the intake valve 11 can be pushed.
And it is necessary to make the knocker 25 larger. Next, the operation of the apparatus of the above embodiment will be explained.

In FIGS. 1 and 2, the camshaft 31 is rotated in synchronization with the engine crankshaft (not shown), and the loaf 27, rocker arm 19, and/or Opening and closing valves such as the intake valve 11 (FIG. 1) and the exhaust valve (not shown) are operated through the hook 25. The state in FIG. 2 shows a high-speed, high-rotation state, and the cam 33 is moved to the left in the figure by the fluid pressure cylinder 35.
The roller 27 contacts the vicinity of the right end surface 33b of the cam 33,
The height of the three-dimensional cam 33 is large, and the valve lift of the engine is required at high speeds, so the valve lift and/or cam phase is required. Next, when switching the engine to a low speed operating state, the hydraulic cylinder 35 is operated to move the power ram 33 to the right in FIG. 2. In this case, since the cam 33 is rotating together with the camshaft 31, the roller 27 rotatably supported on the rocker arm 19 moves in a helical manner on the cam surface of the cam 33, and the cross-sectional shape of the roller 27 is shaped like an arc. Coupled with this, the roller 27 and the cam 33 are moved to the left side of the cam 33 without causing wear or pitching. The lever position then rotates the valve with valve lift and/or valve phase for slow rotation. As described above, in the present invention, since the cross-sectional shape of the roller in the rocker axis direction is arcuate, the relative movement between the roller and the camshaft direction is carried out smoothly without the roller hitting corners, and the pitching of the rocker arm is prevented. does not occur.

In addition, since the rocker arm and the on-off valve are spring-biased, the roller and cam are always in contact with each other, which prevents the roller and cam from colliding once they are separated, and also prevents the roller from colliding with the cam. It is possible to prevent sliding wear caused by contacting the cam again after idling after being separated from the cam. As a result, a variable valve lift engine that is highly durable and reliable can be obtained. Further, according to the present invention, the spring that connects the rocker arm and the on-off valve can be attached to and detached from the side of the rocker arm, so that the spring can be easily attached and replaced. There is no need to remove the members, and the effect is that the work can be done easily.

[Brief explanation of the drawing]

1 is a front sectional view of an embodiment of the present invention, FIG. 2 is a plan view of FIG. 1, and FIG. 3 is a partially sectional side view of FIG. 1. 11... Intake valve, 19... Rocker arm, 21.
．．・Rocker shaft, 27...Roller, 29...Pin, 31
...Camshaft, 33...Cam, 41...Spring. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 A cam having a cam surface that changes continuously in the axial direction of the camshaft is installed on a camshaft that rotates in synchronization with the engine's crankshaft, and the engine is mounted on a rocker shaft that is installed parallel to the camshaft. A rocker arm for opening and closing the toilet is pivotally mounted, the cam shaft and rocker arm are movable relative to each other in the rocker axis direction, a roller is rotatably supported on the cam contact portion of the rocker arm, and a cross section of the roller in the rocker axis direction is rotatably supported. The rocker arm and the opening/closing valve are connected by a spring having an arcuate shape, and the spring is a plate spring having one end removably wound around the rocker arm and the other end shaped into a horizontal U-shape. A variable valve lift engine characterized by: