WO2002027155A1

WO2002027155A1 - Device at a combustion engine with a variable compression

Info

Publication number: WO2002027155A1
Application number: PCT/SE2001/002034
Authority: WO
Inventors: Erik Larsson; Mikael Jönsson
Original assignee: Alvar Engine Ab
Priority date: 2000-09-27
Filing date: 2001-09-21
Publication date: 2002-04-04
Also published as: AU2001290435A1; SE0003443L; SE0003443D0

Abstract

The invention relates to an arrangement in an internal combustion engine having inlet and exhaust valves (1, 2, 3) arranged in the engine cylinder head and operatable by means of a camshaft (4). There are a minimum of three and a maximum of four valves (1, 2, 3). Two of these are inlet or exhaust valves (1, 2) and are located substantially symmetrically in relation to a plane, which passes through the camshaft (4) and the centreline of the remaining valve (3) where there are three valves. Where there are four valves, the plane substantially constitutes a plane of symmetry between the two remaining valves (3). Each pair of valves arranged an operating as a pair and each single valve arranged and operating as a single valve has assigned to it a valve actuator (5a, 5b), designed to be acted upon, against the action of valve springs (1c, 2c, 3c), by corresponding cams (4a, 4b) located on the camshaft (4).

Description

Device at a combustion engine.with a variable copression

The present invention relates to an arrangement according to the precharacterising clause of the claim attached.

In an internal combustion engine it is important that inlet and exhaust valves have areas as large as possible, in order that the intake and exhaust sequences can take place as rapidly as possible with minimal losses, or in other words, so that the functioning and efficiency of the engine will be affected as little as possible by the size of the said areas. From a geometrical standpoint, the problem is to inscribe the largest possible circular areas in the domed head of the combustion chamber. Multi- valve engines with directly acting camshafts conventionally use one camshaft for operating the inlet valves and one camshaft for operating the exhaust valves. Such a construction is bulky and expensive, however, and is therefore not suited to an internal combustion engine with variable compression.

Reference is made to DE 4226 760 Al, DE 4410 122 Al and US 5 626 110 A as examples of the prior art.

The object of the present invention is to create a space and cost-saving construction in an arrangement of the type referred to in the introductory part, in order to provide space for other bulky arrangements intended to create an engine having a compression varying with the power output. This object is achieved by the features specified in the characterising part of the claim.

The arrangement according to the invention also affords the advantage of a very compact construction with fewer bearing points than hitherto known constructions, which reduces the power losses.

The invention will be explained in more detail below with reference to drawings attached in which fig. l shows a diagrammatic perspective view of an embodiment of an arrangement according to the invention having three valves. Figures lb and lc show apian view of an embodiment of an arrangement according to fig. la, viewed from above and below respectively. Figures 2a, 2b show a plan view from above and below respectively of another alternative embodiment of the invention, in which there are two inlet valves and two exhaust valves.

Although it is assumed in the following descriptions of the arrangements according to figures la- Id that one valve is an exhaust valve and the remaining valves are inlet valves, it will be appreciated that in the case of a different engine configuration the opposite may be the case.

In fig. la, 1 generally denotes an exhaust valve. 2 and 3 denote two inlet valves. The valves are supported by their valve stems la, 2a, 3a so that they can slide in a cylinder head (not shown) with seats for the heads lb, 2b, 3b of the valves 1-3. The valves 1-3 are conventionally kept closed by means of valve springs lc, 2c and 3c respectively.

A camshaft 4 with cams 4a, 4b is designed to open the valves 1 or 2 and 3 by way of valve actuators 5a, 5b against the action of the springs lc or 2c and 3c. The invention, as shown in figures la- Id, is characterised in that the centreline 4c of the camshaft 4 lies in a plane, which constitutes a plane of symmetry for the inlet valves 2, 3 and on which the centreline of the exhaust valve 1 is also situated. The valve actuator 5 a is supported so that it can slide in the cylinder head on its circumferential surface.

The valve actuator 5b is supported so that it can slide on two guide columns 6a, 6b and has pressure surfaces 5b2, 5b3 which inscribe only the valve stem 2a, 3 a of each valve 2, 3. This makes the construction extremely compact. It will be seen that with a minimum of one guide column fixed to the valve actuator 5b, the guide column being supported so that it can slide in the cylinder head, a similarly compact construction is obtained.

Figures 2a, 2b illustrate an arrangement according to the invention in an internal combustion engine having four valves 1-3 and 11, with valve heads lb, 2b, 3b and 1 lb, the valves 1 and 11 being arranged and designed to work in a pair with one another, like the valves 2 and 3. As described previously, the valves are acted upon by cams on the camshaft 4 by way of actuators 5b, of the type described in connection with the embodiment according to fig. la, for the operation of a pair of valves.

Claims

Claim

Arrangement in an internal combustion engine with variable compression and having inlet and exhaust valves (1, 2, 3, 11) arranged in the engine cylinder head and operatable by means of a camshaft (4), there being a minimum of three and a maximum of four valves (1, 2, 3, 11), two of these being inlet or exhaust valves (1, 2) and located substantially symmetrically in relation to a plane, wliich passes through the camshaft (4) and the centreline of the remaining valve (3) where there are three valves, and which substantially constitutes a plane of symmetry between the two remaining valves (3, 11) where there are four valves, characterised in that each pair of valves arranged and operating as a pair and each single valve arranged and operating as a single valve has assigned to it a valve actuator (5a, 5b, 5b'), designed to be acted upon, against the action of valve springs (lc, 2c, 3c, 3c'), by corresponding cams (4a, 4b) located on the camshaft 4, and in that a valve actuator (5b) assigned to two valves is either supported so that it can slide on guide columns (6a, 6b) and has pressure surfaces (5b2, 5b3) for operative engagement solely with each valve stem end, or has at least one guide column incorporated into the valve actuator (5b), the column being supported so that it can slide in the engine cylinder head.