JPH0216311A - Variable valve timing device - Google Patents

Abstract

PURPOSE:To simplify a structure, by furnishing interveniently an elastic means between a cam block and another cam block engaged to a movement means, and making movable a plurality of cam blocks having low and high speed cams, by means of one movement means. CONSTITUTION:The 1st and 2nd cam blocks 10,20 provided with low speed and high speed cams 11,12;21,22 respectively which actuate respective valves 101,201, are put with splines on a cam shaft 1. Also, shifter blocks 3,4 engaging with respective cam blocks 10,20 are put on a guide shaft provided in parallel with the cam shaft 1 at the upper part of the cam shaft 1, and the shifter block 3 is made to be movable in a shaft direction through the meshing of a pinion 6 and a rack 5 by the operation of a motor 7. And respective plates 30,40 whose parts overlap mutually are provided on the side portions of respective cam blocks 10,20, and a compression spring 50 is housed at square holes 33,34 formed at these plates and both cam blocks 10,20 are arranged to be coupled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable valve timing device.

(Prior Art) Some modern engines are equipped with a variable valve timing device that changes valve timing and valve lift amount depending on the engine load condition in order to improve output and reduce fuel consumption.

FIG. 3 shows an example of the variable valve timing device. In this device A, a cam block D is formed by integrally forming a low-speed valve opening/closing cam B having a low-speed cam profile and a high-speed valve opening/closing cam C having a high-speed cam profile in parallel. The cam block D is movably spline connected to the cam block D, and a shifter fork F is engaged with the cam block D. The shifter fork F moves in the axial direction of the camshaft E depending on the rotational speed of the engine, thereby moving the cam block D. As a result, the low-speed cam B or the high-speed cam C in the cam block D selectively occupies a position directly above the valve G depending on the engine speed and opens and closes the valve G, thereby efficiently operating the engine. be driven.

In addition, the symbol H in the figure is a rocker arm in the S 011C type engine.

As shown in FIGS. 4(a) and 4(b), the base circle diameters B' and Cr of the low-speed cam B and the high-speed cam C are set to be the same, while the low-speed cam B The lift of the high-speed cam C is set larger than that of the high-speed cam C.For this reason, in the variable valve timing device, the valve G
When switching the cam for operating the valve from cam B to cam C, when valve G is lifted by cam B, the side surface C of the lifted part of knob C is moved as shown by the broken line in FIG.
Since the cam block D cannot be moved because the cam block D comes into contact with the rocker arm 1, when the base circle peripheral surface 8b of the cam B is located on the slipper surface of the rocker arm [-1, in other words, the rocker arm 1- When the cam C is not facing the side area of 1, the cam block D8 is moved to switch the cam.

By the way, in order to obtain stable output in a multi-cylinder engine, as is well known, the stroke phase of each cylinder, in other words, the opening and closing timing of the valves are set to be different from each other. Therefore, when applying the above-mentioned 8-position variable valve timing to a multi-cylinder engine, it is necessary to install the above-mentioned device for each cylinder. Ta.

(Purpose of Light) In view of the above-mentioned circumstances, an object of the present invention is to provide a variable valve timing device for a multi-cylinder engine with a simple structure.

(Structure of the Invention) Therefore, in the present invention, a plurality of cam blocks corresponding to the valves of each cylinder in a multi-cylinder engine are provided on the camshaft with different valve timings, and any one of the cam blocks The above object is achieved by linking a moving means to the block and interposing an elastic means acting in the axial direction of the camshaft between a cam block linked to the moving means and another cam block. .

(Example) Hereinafter, the present invention will be explained in detail based on the drawings.

FIGS. 1(a), 1(b), and 1(c) show an example in which a variable valve timing device according to the present invention is applied to a DOHC type multi-cylinder engine. The camshaft 1 includes a first cam block 10 for operating the valve 101 of the first cylinder 100 and a second cam block 20 for operating the valve 201 of the second cylinder 200. are spline-coupled so that they can move freely in the axial direction.

The first cam block 10 includes a low-speed valve opening/closing cam 1
1 and a high-speed valve opening/closing cam 12 are integrally arranged in parallel, and similarly, the second cam block 20 also has a low-speed valve opening/closing cam 21 and a high-speed valve opening/closing cam 22 integrally arranged in parallel. Further, the first cam block 10 and the second cam block 20 are provided in the power stations 1 to 1 with different valve timings.

Above the camshaft 1, a guide shaft 2 extends parallel to the cam shirts 1 to 1, and this guide shirt! - 2 includes the first cam block 10 and the second cam block 10;
A first shift block 3 and a second shifter block 4, which respectively engage the cam block 20, are movably engaged. Furthermore, a rack 5 is formed in the first shifter block 3 along the axial direction of the guide shaft 2, and a pinion 6 is meshed with the rack 5. pinion 6
A motor 7 is linked to the rack 5, the pinion 6, and the motor 7 to constitute a moving means 8.

A first plate 30 that reaches the side wall of the second cam block 20 is fixed to the side of the first cam block 10, and the second cam block 20 has a first plate 30 fixed to the side of the second cam block 20. An overlapping second plate 40 is fixedly provided. Further, the first plate 30 has long holes 31 and 32 extending in the axial direction of the guide shaft 2, while the second plate 40 has pins 41 and 42 that fit into the long holes 31 and 32, respectively. is permanently installed.

Furthermore, square holes 33 and 43 of the same shape are formed in the first plate 30 and the second plate 40 at positions corresponding to each other, and the square holes 33 and 43 have an axis of action aligned with the force shaft 1. A compression spring 50 as an elastic means is installed so as to coincide with the axial direction of the spring. The compression spring 50 is interposed between the first cam block 10 and the second cam block 20 via the first plate 30, the second plate 40, the first shifter block 3, and the second shifter block 4. It becomes.

When the engine is currently operating in a low rotational speed range, the first shifter block 3 and the second shifter block 4 are operated as follows.
The first cam block 10 and the second nom block 20 are positioned so that the low speed cams 11 and 21 are located directly above the valves 101 and 201, respectively. has been done. Thus the first
The valve 101 of the cylinder 100 is connected to the low speed cam 11 of the first cam block 10 via a shim 102 and a lifter 103.
The valve 201 of the second air 1Fj200 is opened and closed by the low speed cam 21 of the second cam block 20 via the shim 202 and lifter 203. FIG. 2(a) conceptually shows the above-mentioned state.

When the engine speed increases and exceeds the threshold value, the moving means 8 is activated to move the first shifter block 3 to the left in FIG. 2, thereby moving the first cam block 10 to the left. At this time, as shown in FIG. 2(b), the base circle circumferential surface of the cam 11 in the first cam block 10 and the cam 12
When the circumferential surfaces of the base circles of the cam 12 are both facing downward in the figure, in other words, when the circumferential edge of the cam 12 is not occupying the top side area of the valve 101, the first
The cam block 10 is moved from the position shown in Fig. 2 fa) to the position shown in Fig. 2 fb.
), and the high-speed cam 12 occupies the position directly above the valve 101. Note that the top side region of the valve 101 is a region on the side of the lifter 103 and
This refers to an area lower than the slipper surface of No. 03. On the other hand, as the first plate 30 moves to the left as the first shifter block 3 moves, the second plate 40 is also moved via the compression spring 50, thereby causing the first cam block 20 to move to the left. At this time, if the lift part 22a of the high-speed cam 22 in the second cam block 20 is facing downward as shown in FIG. 2(b), the lift part 22a will hit the lifter 203, The second cam block 20 moves slightly to the left from the position shown in FIG. 2(a) to the position shown in FIG. 2(b) and then stops. Therefore, a relative positional shift occurs between the first plate 30 linked to the first cam block 10 and the second plate 1-40 linked to the second cam block 20, and the square hole 33 The compression spring 50 is compressed and deformed by the edge 33a of the square hole I3 and the edge 43a of the square hole I3 as shown in FIG. 2(1). The camshaft 1 rotates from the state shown in FIG. 2(b) to the state shown in FIG. When facing downward, in other words, at a time when the peripheral edge of the cam 22 is not occupying the top side region of the valve 201, the second cam block 20 is compressed by the compression spring 5.
Due to the elastic return force of 0, the position shown in Fig. 2(b) changes from the position shown in Fig. 2(b) to Fig. 2(
It instantly moves to position C), and the high-speed cam 22 occupies the position directly above the valve 201. Thus, valve 101.20
1 are opened and closed by high-speed cams 12 and 22, respectively. Note that the top side region of the valve 201 here refers to a region on the side of the lifter 203 and lower than the slipper surface of the lifter 203.

When the engine speed decreases from the high speed range and falls below the threshold, the moving means 8 operates in reverse and the first shifter block 10 moves to the right, and the first plate 30, compression spring 50,
and the second thick block 2 via the second plate 40.
0 also goes to the right. At this time, each cam block 10.2Of
, :The low speed cam 11.21 is the high speed cam 12.
Since the lift width is set 6 times smaller than that of 22, each cam block 10.20 moves smoothly to the right without the low-speed cam 11.21 getting caught on the lid 103.203 of each valve 101, 201. , valve 101.2
The low speed cam 11.21 is located directly above the cam 01. Thus, each valve 101, 201 is opened and closed by the low speed cam 11.21.

In this example, an engine with two cylinders facing each other is illustrated, but it goes without saying that the present invention can also be effectively applied to an engine with three or more cylinders. Further, the elastic means is not limited to a compression spring; for example, when the moving means 8 is provided in the second shifter block 20 of FIG. 1, it goes without saying that the apparatus functions by using a tension spring as the elastic means.

(Effects of the Invention) As detailed above, according to the variable valve timing device according to the present invention, an elastic means is interposed between the cam block linked to the moving means and the other cam block, and both cams When the cam blocks cannot be moved simultaneously, the relative displacement between both cams is absorbed by the elastic means, and when the other cam block becomes movable, the restoring force of the elastic means is used to move the cam block of the above function. So,
A plurality of cam blocks corresponding to a plurality of cylinders can be operated by one moving means.

As a result, it has become possible to switch valve timing in a multi-cylinder engine with a simple structure.

[Brief explanation of the drawing]

FIG. 1(a) is a plan view of a variable valve timing device according to the present invention, FIG. 1(b) is a sectional view taken along line bb of FIG. 1(a), and FIG. 1(C) is a camshaft area. Figure 1 shows (
It is a sectional view taken along the line C-C of b), and FIG. 2 (aHb) (c)
3 is a conceptual cross-sectional side view sequentially showing the operation mode of the variable valve timing device according to the present invention, and FIG. 3 is a cross-sectional side view of the main part showing a conventional variable valve timing device.
Figure 4 [a] and (b) are IVa- in Figure 3, respectively.
They are an IVal sectional view and an IVb-IVb line sectional view. DESCRIPTION OF SYMBOLS 1...Camshaft, 2...Guide shaft, 3゜4...Shifter block, 8...Moving means, 10.2
0...Cam block, 11.21...Low speed valve opening/closing cam, 12.22...High speed valve opening/closing cam, 3
0゜40...Plate, 50...Compression spring, 100
．． 200...Cylinder, 101.201...Valve Applicant Suzuki Motor Co., Ltd. 2nd Zusai

Claims (1)

[Claims] A cam block, which is made up of multiple valve opening/closing cams with different cam profiles arranged side by side and integrally formed, is fitted onto a camshaft so that it cannot rotate but is movable in the axial direction, and is used as a cam that operates the valves. The valve is operated by moving the cam block in a direction in which the adjacent cam occupies the area immediately above the valve at a time when the peripheral edge of the adjacent cam does not occupy the top side area of the valve. The variable valve timing device is a variable valve timing device that selectively switches a cam to be activated, and the variable valve timing device is provided with a plurality of cam blocks corresponding to the valves of each cylinder in a multi-cylinder engine on the camshaft with different valve timings. , and a moving means is linked to any one of the cam blocks, and elastic means acting in the axial direction of the camshaft is interposed between the cam block linked to the moving means and the other cam block. A variable valve timing device characterized by: