Valve Actuation Device for Multi-Valve-Type Engine

Europaisches Patentamt European Patent Office © Publication number: 0 324 092 Office europeen des brevets A1

© In an engine having three or more inlet valves (5), an inlet camshaft (10) is disposed on a valve seat (5c) side from the phantom axis (12) on which the axes of the inlet valves (5) cross. Engagement is achieved with a slight offset (x) between the inlet camshaft (10) and each lifter (9) driven by the inlet camshaft (10). The inlet valves (5) are driven by rotation of the inlet camshaft (10) through the lifters (9). Such a reduction of height and width of a cylinder is provided. x FIG.1

CM C> O

CM CO

CL 111

Xerox Copy Centre 1 EP 0 324 092 A1 2

VALVE ACTUATION DEVICE FOR MULTI-VALV-TYPE ENGINE

Detailed Description of the Invention: Function:

Since the inlet camshaft 10 is disposed on the Industrially Applicable Field: valve seat 5c side from the phantom axis 12 on 5 which the axes of the inlet valves 5 cross, the This invention relates to an improvement in a height of the engine is lowered so much. The cylinder head structure of a four-stroke engine hav- engagement is achieved with a slight offset be- ing a so-called dual-cam-type actuation device in tween the inlet camshaft and each lifter 9 driven by which an inlet camshaft for actuating inlet valves the inlet camshaft or between each lifter and the and an exhaust camshaft for actuating exhaust w axis of the corresponding inlet valve. The inlet valves are provided separately from each other. In valves are driven by rotation of the inlet camshaft particular, the object of the present invention is to through the lifters. reduce as much as possible the overall height of an engine of the above-mentioned type in which the height is liable to become large. 75 Embodiment:

The present invention will be described below Prior Art: with reference to the illustrated embodiment. In the Figures, designated as 1 is a four-stroke engine In recent years, inlet and exhaust valves have 20 having a combustion chamber 2 defined by a cyl- been actuated separately by camshafts in order to inder head 3, a cylinder 4 and a piston 5. Three improve the output of a car engine at a high speed inlet valves 5 and two exhaust valves 6 are dis- (for example, Japanese Laid Open Patent Publica- posed along the inside surface of a cylinder bore tion No. 59-165,810). 4a of the cylinder head 3, thereby to form a so- 25 called semispherical combustion chamber. The reference numeral 7 denotes an inlet passage leading Problems To Be Solved By the Invention: to the combustion chamber 2 through each inlet valves 5, and 8 an exhaust passage leading to the Since each of the camshafts of this type of combustion chamber 2 through each exhaust valve engine is disposed in the direction of the axis of 30 6. the valve shaft, the height and the width of the These inlet valves 5 and exhaust valves 6 are cylinder head tend to become large. For this rea- actuated by a common inlet camshaft 10 and a son, when such an engine is mounted on a car, an common exhaust camshaft 11, respectively, interference against an engine room walls is apt to through valve lifters 9 each slidably fitted into a be caused. Thus, there is involved a difficulty in 35 guide hole 3a of the cylinder head 3. satisfying a recent demand for reducing the volume Of the above-mentioned three inlet valves 5, of an engine room. the both side two valves 5a and 5a are disposed in parallel with each other and the central valve 5b is disposed obliquely relative to the both side valves Means for Solving the Problems: 40 5a and 5a with an angle similar to the axis of the cylinder bore 4a. The axes of these valves cross at The present invention has as its object the a point on a phantom axis 12 which is in parallel solving of the above-mentioned problems and re- with the axis of the inlet camshaft 10. The axis 10a duction of the height and width of a cylinder head of the inlet camshaft 10 is located at a position as much as possible, and provides a device com- 45 nearer to a valve seat 5c of the inlet valve than the prising three inlet valves disposed on an inside phatom axis 12 is. Thus, there is a slight offset X surface of a cylinder bore, and a common inlet between the axis of the inlet camshaft and the axis camshaft for actuating the inlet valves through of the valve lifter 9 as shown in Fig. 2, or between valve lifters, wherein the axes of the three inlet the axis of the valve lifter 9 and the axis of the inlet valves cross on a phantom axis which is in parallel so valve 5. Designated as 13 is a valve spring. with the axis of the inlet camshaft and wherein the Next, the operation of this embodiment will be axis of the inlet camshaft is located on the valve explained. When the inlet camshft 10 is rotated by seat side from the phantom axis. rotation of a crank shaft, the valve lifter 9 is dis- placed to push and open the inlet valve 5 against the valve spring 13 or is moved, while maintaining

2 3 EP 0 324 092 A1 4 in contact with the inlet camshaft 10, by the resil- three inlet valves cross on a phantom axis which is ient force of the valve spring 13. These operations in parallel with the axis of the inlet camshaft and are quite the same as those in conventional device. wherein the axis of the inlet camshaft is located on In the present invention, the inlet camshaft 10 the valve seat side from the phantom axis. is desposed on the valve seat side from the phan- 5 tom axis 12 on which the axes of inlet valves 5 cross. Thus, the engagement is achieved with a slight offset between the inlet camshaft 10 and the valve lifter 9 driven by the inlet camshaft or between the valve lifter 9 and the axis of the inlet 10 valve 5. Since the valve lifter 9 has relatively a large diameter and since the area of contact between the lifter and the sliding surface in the cylinder head 3 is also large, it is possible to prevent a large biasing force from acting on the inlet valves 15 5 by suitably adjusting the gap in the sliding surface.

Effect of the Invention: 20

As described in the foregoing, since, the present invention provides a device comprising three inlet valves 5 provided along a cylinder bore 4a of a cylinder head 3, wherein the axes of the 25 three inlet valves 5 cross on a phantom axis 12 which is in parallel with the axis of the inlet camshaft 10 and wherein the axis of the inlet camshaft 10 is located on the valve seat 5c side from the phantom axis 12, the height of an engine can be 30 lowered so much, thereby to give an effect that the engine can be accommodated in a relatively small engine room.

35 4. Brief Description of the Drawings:

The drawings illustrate one embodiment ac- cording to the present invention, in which Fig. 1 is a cross-sectional view of an engine; Fig. 2 is a view 40 showing a relationship between an inlet valve and a camshaft; and Fig. 3 is a view, corresponding to Fig. 2, showing another embodiment. 3a... guide hole, 4a... cylinder bore, 45 5... inlet valve, 10... inlet camshaft, 12... phantom axis, X... offset 50

Claims

(1) A valve actuation device for a multi-valve- type engine, comprising three inlet valves disposed on an inside surface of a cylinder bore, and a common inlet camshaft for actuating the inlet valves through valve lifters, wherein the axes of the

3 EP 0 324 092 A1 European Patent Number EUROPEAN SEARCH REPORT Application Office

EP 88 11 9821

DOCUMENTS CONSIDERED TO BE RELEVANT Category Citation of document with indication, where appropriate, Relevant CLASSIFICATION OF THE _^ of relevant passages to claim APPLICATION ant. CI. 4) DE-A-3 524 622 (AUDI AG) F 01 L * Column 2, lines 32-66; column 3, 1/26 lines 3-16; figures 1-4 *

EP-A-0 063 385 (YAMAHA MOTOR CO. LTD) * Page 4, lines 25-29; page 4, line 36 - page 5, line 1; figures 1-4 *

TECHNICAL FIELDS SEARCHED ant. C1.4)

F 01 L

The present search report has been drawn up for all claims Place of search Date of completion of the search Examiner THE HAGUE 31-03-1989 LEFEBVRE L.J.F.

CATEGORY OF CITED DOCUMENTS T : theory or principle underlying the invention E : earlier patent document, but published on, or X : particularly relevant if taken alone after the filing date Y : particularly relevant if combined with another D : document cited in the application document of the same category L : document cited for other reasons A : technological background O : non-written disclosure & : member of the same patent family, corresponding P : intermediate document document