WO1997000375A1

WO1997000375A1 - Valve spring arrangement

Info

Publication number: WO1997000375A1
Application number: PCT/SE1996/000776
Authority: WO
Inventors: Ulf NÄSLUND
Original assignee: Aktiebolaget Electrolux
Priority date: 1995-06-15
Filing date: 1996-06-14
Publication date: 1997-01-03
Also published as: SE9502175L; SE9502175D0; AU6143796A

Abstract

The subject invention refers to a valve spring arrangement for internal combustion engines. In these are included a cylinder body (1, 2), one in this oscillating piston (3), which together with the cylinder body form a combustion chamber (4), and a valve (6, 7). By a valve disc (6) this valve closes/opens an inlet-/outlet channel (5) in the cylinder body (1, 2), and with a shaft (7) passes out through the cylinder body (1, 2). According to the subject invention the valve shaft (7) is directly connected with a plate spring (8), which is fastened to the cylinder body (1, 2), and preferably bent between its fastening ends (9, 10) at the cylinder body (1, 2) and the valve shaft (7).

Description

VALVE SPRING ARRANGEMENT

The invention refers to a valve spring arrangement for internal combustion engines with a cylinder body, one in this oscillating piston, which together with the cylinder body form a combustion chamber, and a valve, which by a valve disc, closes/opens an inle outlet channel in the cylinder body and with a shaft passes out through the cylinder body.

A valve to an internal combustion engine is normally provided with a screw spring and a spring washer. The valve must also have some kind of control for its opening- and closing movements.

By earlier known designs have been used, as an example of simple control and spring action on a valve for a combustion chamber, spirally wounded wire springs, which from two sides have been connected with the valve via intermediate fastening elements. This design can nearly be compared with the spring arrangement of a clothes-peg.

The purpose of the subject invention is to achieve a very simplified design for spring affection of a valve for in first hand such internal combustion engines, which are used for working tools, such as chain saws, lawn mowers etc., where the space usually is most limited and demand for low cost of the entire design requires a simple technical solution.

By the origin of this invention these demands have been satisfied. What above all characterizes this invention is that the valve shaft is directly connected with a plate spring, which is fastened to the cylinder body. By this design no intermediate fastening elements between the valve shaft and the spring are needed, whereby the airangement requires only a limited total height.

Preferably the plate spring is bent between its fastenings at the cylinder body and the valve shaft, whereby the valve is exposed to only minimal side-forces. These and other characteristics of the invention will be described in closer detail in the following with reference to the enclosed drawings, in which Figure 1 shows a vertical section through a cylinder, which is provided with the arrangement according to one embodiment of the invention. Figure 2 shows the same section with a complimentary addition to the embodiment of Figure 1. Figure 3 shows a similar vertical section with another embodiment ofthe arrangement according to the invention, and Figure 4 shows a section along line IV-IV in Figure 3. In all of these shown embodiments of the drawing only a part of an internal combustion engine is shown. Thus only one cylinder body is included which can be performed as a part in one piece, but in the drawing it has been shown as a part of a cylinder 1, and a cylinder top 2 applied to this cylinder 1. These together with one in the cylinder 1 running piston 3 form a combustion chamber 4. The cylinder top 2 is provided with an inlet-/outlet channel 5, which is sealable by a valve, which consists of a valve disc 6, and a shaft 7 which is passing out through the cylinder top 2.

According to the invention the valve shaft 7 is directly connected with a plate spring 8. At one end 9 the blade spring is connected with the cylinder 1, or, as shown in the drawing, with the cylinder top 2, and at its opposite end 10 the plate spring 8 is inserted in a groove 11 in the valve shaft 7.

Since the middle part of the plate spring 8 is bent preferably so much that its fastening ends 9 and 10 essentially form an angle of 90° to each other, the plate spring 8 gives no, or at least very little side-forces, onto the valve. In Figure 2 is shown a variant where the plate spring 8 is provided with a down bent part 12, which serves as a pressure area for an eccentric part of a camshaft 13. This variant shows that no extra equipment will be required, but that the valve 6, 7 instead can be affected only by the pressure towards the plate spring 8 via the eccentric part ofthe camshaft 13. Figure 3 and 4 shows another variant where the plate spring is provided with an extended part 14 protruding past the valve shaft 7, as seen from the fastening end 9 ofthe plate spring 8. This extended part 14 is connected to a draw bar 15, which is arranged so that it by displacement movements in its longitudinal direction via the plate spring 8 can open and close the valve 6, 7. The displacement movements ofthe draw bar 15 are accomplished, which is not shown in the drawing, by, in itself a known way, either a low lying camshaft, or a cam in a double groove in the crankshaft belonging to the internal combustion engine.

The new technique according to the invention can by advantage be used in a future development phase of internal combustion engines referred hereto. By making the valve shaft 7 thicker than normally the direct connection between the shaft 7 and the plate spring 8 can be facilitated. The valve 6, 7 is produced according to conventional technique, of steel, and the cylinder top of aluminium, and the valve shaft 7 runs in a bush in the cylinder top 2. In case the cylinder top 2 instead should have been produced in a harder more durable, so called MMC- material, in which silicon carbide is included, the abovementioned bush could be excluded due to the more robust design ofthe valve shaft 7. By the stronger valve shaft 7 also the heat dissipation ofthe valve 6, 7 will be improved. The invention is not restricted to the shown and described performances, and can of course be varied in several ways within the scope of following patent claims. This is valid both for the bending of the plate spring 8 and for its fastening into the valve shaft 7.

Claims

1. Valve spring arrangement for internal combustion engines with a cylinder body (1, 2), one in this oscillating piston (3), which together with the cylinder body (1, 2) form a combustion chamber (4), and a valve (6, 7), which by a valve disc (6), closes/opens an inlet-/outlet channel (5) in the cylinder body (1,2), and with a shaft passes out through the cylinder body (1, 2), charac¬ ter i z e d in that the valve shaft (7) is directly connected with a plate spring (8), which is fastened to the cylinder body (1,2). 2. Valve spring arrangement according to claim 1, characte¬ rize d in that the plate spring (8) is bent between its fastening ends (9, 10) at the cylinder body (1,

2) and the valve shaft (7).

3. Valve spring arrangement in accordance with anyone ofthe preceding claims, characterized in that the plate spring (8) between its fastening ends (9, 10) is provided with a bent part (12) which serves as a pressure area for an eccentric part of a camshaft (13).

4. Valve spring arrangement in accordance with anyone ofthe preceding claims, characterized in that the plate spring (8) is provided with an extended part (14) protruding past the valve shaft (7), as seen from the fastening end (9) ofthe plate spring (8) in the cylinder body (1, 2), and this extended part (14) is connected to a draw bar (15) which is arranged to be able to perform displacement movements in its longitudinal direction for opening and closing ofthe valve (6, 7).