AU719711B2

AU719711B2 - Air cooled power machine

Info

Publication number: AU719711B2
Application number: AU35653/97A
Authority: AU
Inventors: Gunnar Leijonberg
Original assignee: Gul and Co Dev AB
Current assignee: Gul & Co Development AB
Priority date: 1996-07-12
Filing date: 1997-07-10
Publication date: 2000-05-18
Anticipated expiration: 2017-07-10
Also published as: JP4091985B2; DE69710893D1; DE69710893T2; WO1998002639A1; CA2260141A1; JP2000515216A; EP0910726B1; AU3565397A; ATE214123T1; SE508375C2; SE9602758D0; EP0910726A1; SE9602758L; NZ334072A; CN1225149A; CN1087808C; RU2175066C2

Abstract

The present invention is for the kind of power machine, engines, pumps or compressors which have two or more pistons which work against each other preferably with a common combustion space or corresponding in a stationary cylinder, and where the power is transmitted to or from a rotating motion without an intermediate crankshaft. Independent of whether the machine works as engine, pump or compressor there is a need to cool the cylinder. For applications such as engines for lawn-mowers and power saws the engines must be air-cooled as in practice it is not possible to arrange a water-cooling system. Cooling of the cylinder is obtained by that holes or channels (30, 31) are arranged both in the rotating and the stationary discs and cooling air is made to flow through these channels. In order to further improve the cooling the outside of the cylinder may have flanges. In other embodiments of the invention the connecting means between the rotating disc and the outgoing shaft are so shaped that they also function as fan blades (34-35) and cause a desired air flow.

Description

WO 98/02639 1 PCT/SE97/01260 Air cooled power machine The present invention is for the kind of power machines, engines, pumps or compressors which have two or more pistons which work against each other and preferably have a common combustion space within a stationary cylinder and where the power is transmitted to or from a rotating movement without an intermediate crankshaft.

Independent of wether the machine works as an engine compressor or pump there is a need to cool the cylinder bore. For certain applications such as engines for lawn-mowers and power saws these must be cooled by air as it in practice is very difficult or impossible to arrange a water cooling system.

At combustion engines the transmission of force from a to and from motion to a rotating motion generally is by means of some kind of crankshaft or the like. In certain cases however crankshafts are less suitable, and this is especially the case when to and from motions with different, often directly opposite directions together shall be transmitted into a rotating motion.

Especially this is the case by that kind of power machines e.g.

combustion engines, compressors or pumps, where two pistons at the same time work against each other in a common cylinder bore. In these cases the use of crankshaft bring with them complicating mechanical designs to put together the power from the two pistons into one common rotating motion. The transmission of force between a to and from motion and a rotating motion may instead take place using a ball bearing which runs in several tracks and includes a ball which is surrounded by a ball holder which is attached to one piston rod or the like member for each ball for transmission of the linear motion into rotating motion. It is also possible to exchange the balls for other means with corresponding functions, for example rolls or pins which roll or slide in the tracks.

One such device has two parallel plane discs both a stationary disc and one relatively thereto rotating disc. In one relative to the disc centrally positioned cylinder there are two pistons which are working pistons of a combustion engine, and have a common combustion space. Fixedly joined to each piston there is a piston rod which at its opposite end has a holder means for the ball by which the force from the to and fro motion is transmitted to the rotating disc. The balls also serve as bearing between the stationary disc and the rotating disc. The rotating disc is mounted onto a holder which in turn is mounted onto an outgoing shaft from which the rotating force is taken for use for various driving purposes. The balls can move both in linear tracks in the fixed disc, and in a common elliptic or otherwise closed shaped track in the rotating disc. In other embodiments tracks may be substituted for by raised edges where roller or slide bearings contact the sides of the edges.

The present invention provides a power transmission device having: a rotatable first disc-like member; a fixed second disc-like member; Se two pistons arranged in a common cylinder bore to work synchronously against each other, said cylinder bore being fixed relative to said second disc-like member; means for transmission of power between a linear motion of said pistons and a 20 rotation motion of said first disc-like member, said means comprising two cam means, each driveable by a said piston, and a curved cam track provided on said first disc-like member, wherein each said cam means engages said cam track for transmitting a linear :motion of said pistons into a rotation of said first disc-like member; and a. •.openings formed in the centre of said disc-like members so that cooling air may S 25 pass through these openings and along the outside of the cylinder bore.

S°There are special difficulties in arranging air-cooling for machines of the above *•0°0 a .mentioned kind. Known designs of the power transmission mechanism have brought with it a design of the machine in its entirety such that it has not been possible to arrange a sufficient cooling air flow.

3o Preferred forms of the present invention will now be described by way of example only with reference to the accompanying drawings, wherein: WO 98/02639 PCT/SE97/01260 Figure 1 shows a cross section of a machine according to the invention.

Figure 2 shows the machine of figure 1 in cross section at right angle to figure 1.

Figure 3 shows the machine of figure 1 in cross section at right angles to figures 1 and 2.

Figure 4 shows another embodiment of the invention in a cross section corresponding to figure 2.

Figure 5 is a perspective view of the invention with some parts removed and in partial cross section.

The device shown in the figures has two parallel plane discs, one which is named stationary disc 8 and one relatively thereto rotating disc 13. The stationary disc 8 is carried by a housing 9 and the disc 8 in turn carries one in its centre positioned cylinder 1 having end walls 2, 3. In the cylinder there are two pistons 4, 5 which are working pistons, and in a combustion engine preferably have a common combustion space.

Fixedly joined to each of the piston 4, 5 is a piston rod 6, 7 which at its opposite end has a holder means 17, 18 for the ball 15, 16 by which the force from the to and fro motion is transmitted to the rotating disc 13. The balls 15, 16 also serve as bearing between the stationary disc 8 and the rotating disc 13. The rotating disc 13 is mounted onto a holder 10 which in turn is mounted onto an outgoing shaft 23 from which the rotating force is taken to be used for various purposes. In the preferred embodiment of the invention the centre axes of the cylinder bore coincides with the line of movement of the balls.

WO98/02639 PCUSE97/01260 The balls 15, 16 can move both in linear tracks 11, 24 in the fixed disc and in a common elliptic track 12 in the rotating disc.

Valves may be arranged adjacent to the upper dead centre, UDC, of the pistons at opposite sides in the centre of the cylinder bore. In the cylinder there are corresponding valve seats and the shafts are designed in consideration of the through bores and stearings which are in stationary parts closed to the cylinder. Preferably the from the cylinder outer ends of the valve shafts directly contact a regulating curve or contact surface which is a part of the rotating disc.

Cooling of the cylinder is obtained by that holes or channels 31 are arranged both in the rotating and the stationary discs and cooling air flows through these channels. In order to further improve the cooling the outside of the cylinder may have flanges 32, as shown in figure 1. In a preferred embodiment of the invention the conveyance of cooling air to or from the rotating disc is by means of a hollow shaft 33, which is connected to this disc. The flow of air may take place either directly inside the shaft or inside one in the shaft mounted stationary tubular means. This tubular means may be directly or indirectly joined to the stationary disc. Cooling air is directed to both sides of the cylinder and in those cases where the power machine is equipped with valves which are arranged mainly at right angle to the direction of movement of the pistons, four such cooling channels may be arranged. In other embodiments of the invention the means which connect the rotating disc and the outgoing shaft are so designed that they also function as fan blades 34, 35 and cause a desired air flow.

A preferred embodiment of the invention is shown in figure Here the stationary disc is built together with, or forms a WO 98/02639 PCT/SE97/01260 part of the housing which fully surrounds the rotating disc.

All lubricated parts of the device are within this housing which downwards (according to figure 5) is delimited by an oil sealed bearing. The outgoing shaft from the rotating disc is hollow and cooling air is directed through the shaft to the inner bowl shaped volume wherein the cylinder having cooling flanges is positioned.

The airflow may in some applications be used also for other purposes than cooling only. When the power machine is used as a engine for lawn-mowers the airflow may be directed to the cut grass and affect this either to be blown to a collector at the lawn-mower or flow back to the knives to be cut into smaller pieces.

Claims

1. A power transmission device having: a rotatable first disc-like member; a fixed second disc-like member; two pistons arranged in a common cylinder bore to work synchronously against each other, said cylinder bore being fixed relative to said second disc-like member; means for transmission of power between a linear motion of said pistons and a rotation motion of said first disc-like member, said means comprising two cam means, each driveable by a said piston, and a curved cam track provided on said first disc-like lo member, wherein each said cam means engages said cam track for transmitting a linear motion of said pistons into a rotation of said first disc-like member; and openings formed in the centre of said disc-like members so that cooling air may pass through these openings and along the outside of the cylinder bore.

2. The power transmission device according to claim 1 wherein the second disc-like member is connected to or forms a part of the housing which fully surrounds the first disc-like member.

The power transmission device according to claim 1 or 2 wherein the first disc-like member further includes fan blades which cause a forced flow of cooling i: :air.

4. The power transmission device according to claim 3 wherein the first disc-like member is connected to an outgoing shaft from the engine by means of the fan blades. The power transmission device according to claim 4 wherein the outgoing shaft from the first disc-like member is hollow and wherein cooling air passes 25 through the shaft.

S. S [R:\LIBLL]08971 .doc:MFF

6. A device substantially as hereinbefore described with reference to Figs. 1 to 3; Fig. 4; or Fig. 5 of the accompanying drawings. Dated 4 February, 1999 Gui Co. Development AB Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON 0S @0 S 0 0 00 0 S 00@ S OS SO 0 OS 0 0 500 0 05 0O 0 *050 S. 05 0 OS 00 S 55 0 S 0 S. .55. 0 OOSS 0 @00000 0 'KA/ [~'N:)O782 i- p