GB2213226A

GB2213226A - Power transmission device

Info

Publication number: GB2213226A
Application number: GB8728583A
Authority: GB
Inventors: Stan Cucek
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-12-07
Filing date: 1987-12-07
Publication date: 1989-08-09
Also published as: GB8728583D0

Abstract

A power transmission device comprising one or more reciprocable input shafts (9), eg. the connecting rods of an internal combustion engine, first and second one way clutches (4, 5) and a rotatable output shaft (1), arranged so that motion of the input shafts (9) in a first direction is transmitted through the clutches (4, 5) to the output shaft (1) causing this to rotate in a first direction (A) whereas motion of the input shafts. (9) in a second direction is not transmitted through the clutches (4, 5) to the output shaft (1). The timing of the motion of the input shafts (9) may be controlled by a crankshaft (12) connected thereto by linking members (10). In an alternative arrangement (Fig. 4), motion of a drive shaft (51) in a first direction is transmitted to the output shaft (55) by the first clutch and motion of the drive shaft (51) in a second direction is transmitted to the output shaft (55) by the second clutch. <IMAGE>

Description

POWER TRANSMISSION DEVICE DESCRIPTION The present invention relates to a power transmission device for converting reciprocal motion of an input shaft into substantially continuous rotational motion of an output shaft.

The most commonly employed device for converting reciprocal linear motion of a member, such as a piston, into a rotating output, is a crankshaft. In such an arrangement, a piston is connected by a rigid rod to the cranked portion of a crankshaft.

Reciprocation of the piston causes the cranked portion to rotate about the portion of the crankshaft journalled in a fixed bearing, thereby causing said journalled portion to rotate in its bearing. Such a rotating crankshaft may then be employed to do work, such as to drive the wheels of a motor vehicle through a suitable transmission device.

Disadvantages of the crankshaft include uneven torque transmission from the connecting rod to the crank, especially at the extremities of the connecting rod's movement, where very small linear movements of the connecting rod, and hence an associated piston, correspond to relatively large angles of rotation of the crankshaft. In order to smooth out the variations, crankshafts traditionally have been run at high rates of rotation. Other methods of overcoming this uneveness have included the use of a plurality of connecting rods and pistons journalled to a single crankshaft at differing crank angles in addition to high crankshaft speeds.

The present invention provides an improved means of translating reciprocal motion into substantially continuous unidirectional rotational motion. According to the present invention there is provided a power transmission device comprising at least a first reciprocable input shaft, at least a first and a second one way clutch means and, a rotatable output shaft; the arrangement being such that motion of the input shaft in a first direction is transmitted through the first one way clutch to the output shaft, causing the latter to rotate in a first direction, the second clutch being arranged to drive the output shaft in the first direction in response to either, motion of a second reciprocable input shaft in its first direction, or motion of the first input shaft in a second direction; motion of the first input shaft in its second direction is not transmitted through the first one way clutch and motion of a second input shaft in its second direction is not transmitted through the second clutch.

The term "one way clutch" is used throughout this specification to describe a device which comprises rotatable input means and rotatable output means.

Rotation of the input means in a first direction is transmitted through the clutch causing the output means to rotate in said first direction; whereas rotation of the input means in a second direction is not transmitted to the output means. Suitable one way clutches, for use in embodiments of the present invention, include the over-running clutches manufactured under the Trade Mark FORMSPRAG by Dana Incorporated.

In an embodiment the first reciprocal shaft is a toothed rack member reciprocal in a lengthwise direction and arranged to drive the output shaft in unidirectional rotation; through the first one way clutch when moving in the first direction and through the second one way clutch when moving in the second direction. In an alternative arrangement the first reciprocable input shaft is reciprocable in rotation about its axis, in alternate clockwise and anticlockwise directions and is arranged to drive the output shaft unidirectional rotation; through the first one way clutch when rotating in a clockwise direction and through the second one way clutch when rotating in an anticlockwise direction.

In a preferred embodiment the device comprises at least a first and a second input shaft, both reciprocable in lengthwise directions and both controlled by a crankshaft arranged to time the reciprocation of said input shafts so that the output shaft is driven substantially continuously. In a preferred form of this embodiment, each full stroke of an input shaft causes the output shaft to rotate through an angle of less than go and preferably less than 60 .

Preferably each one way clutch comprises inner and outer rotatable members with one way transmission means therebetween, the input shafts are coupled to the outer rotatable members and drive to the output shafts is taken from the inner rotatable members. The input shafts may be journalled to arms extending radially outwardly from an intermediate shaft arranged to be reciprocated in rotation) which intermediate shaft is driveably connected to the one way clutches.

In a further embodiment the input shafts are the connecting rods of an internal combustion piston engine, the end parts of which connecting rods, remote from the clutches, are driven by the pistons of said internal combusion engine.

Advantages of the present invention, are pricipally derived from the fact that torque transmission from reciprocating input shafts to the rotating output shaft are much less uneven than would be the case if a conventional crankshaft were used. Hence the need for torque multiplying devices is obviated.

In embodiments of the present invention which employ a crankshaft, the crankshaft does not serve the purpose of transmitting torque, it is merely employed to keep the reciprocating input shafts correctly timed. Thus such a crankshaft must have its cranks appropriately angled to avoid "fight" between input shafts. Furthermore, it should be noted that the rotation of the crankshaft will not be uniformed when the rate of rotation of the output shaft is constant.

Particular embodiments of the present invention will now be described with reference to and as shown in the accompanying drawings; wherein: Figure 1 is a schematic diagram showing a power transmission device in accordance with the present invention; Figure 2 is a partially sectioned side view of an internal combustion engine incorporating power transmission device in accordance with the present invention; Figure 3 is a partially sectioned end view of the engine shown in Figure 2 and; Figure 4 is a schematic view of a power transmission device in accordance with the present invention coupled to a "free piston" motor.

With reference to Figure 1, a rotable output shaft I is journalled in fixed bearings 2 and 3 holding the shaft 1 at its end parts. Two one way clutch devices 4 and 5 are engaged upon the shaft 1 between the bearings 2 and 3. Each one way clutch device 4 and 5, comprises an inner race 6 in fixed relationship with the shaft 1 and an outer race 7 concentric with the inner race 6. Between the race 6 and 7 are means (not shown) of a conventional form which cause the outer races 7 and to become fixed in rotation to the inner races 6 when the outer races 7 are rotated in the direction of arrow A: the outer races being free to rotate in the opposite sense to the arrow A, without engaging with the inner races 6.

Arms 8 extend raidally outwardly from the outer races 7. Journalled to the outer end parts of the arms 8 are driven connecting rods 9 and linking member 10.

The rods 9 are arranged so as to be able to reciprocate in the direction of the arrows B. The upper ends of the driven connecting rods 9 (not shown) may be connected to any source of reciprocating motion, for example to the pistons of an internal combustion engine.

The linking members 10 extend from the arms 8 to the cranked portions 11 of a crankshaft 12. The crankshaft 12 is journalled in bearings 13, which bearings 13 are fixed in relation to the bearings 2 and 3. The cranked portions 11 of the crankshaft 12, to which the arms 8 are journalled, are separated by a crank angle of 1800.

In Figure 1, only two driven connecting rods 9 are shown. This number is a minimum requirement, however four such rods may be included in the illustrated design, the other two rods being attached to the arms 8 which are shown unencumbered in the drawings.

In use reciprocation of the driven connecting rods 9 will cause the output shaft 1 to rotate in the direction of arrow A. The extent and timing of such reciprocation is controlled by the crankshaft 12.

Thus, when drive is being imparted to the shaft 1 through the clutch 5, the outer race of clutch 4 is pushed in the opposite direction, via the crankshaft 12 and the links 10 and does no work upon the output shaft 1 and, vice versa. Thus in a typical application such as in a gasoline engine or steams engine, the rods 9 are forced in a direction downwards in Figure 1 by the engine's pistons and the pistons are returned to the top of their stroke via the crank shaft 12, which acts to maintain at least one piston in a power producing downwardly moving portion of its cycle.

A four cylinder internal combustion engine is shown in Figures 2 and 3, which engine is a practical embodiment of the arrangement shown in Figure 1. The engine comprises a combined crank case and cylinder block 20 defining four horizontally opposed cylinders 21. A conventional piston 22 is slidably engaged in each cylinder 21. Each pair or cylinders 21 is capped by a conventional cylinder head 23 which includes conventional valve gear, camshafts and sparking plugs. The remaining components of the engine shown in Figures 2 and 3 correspond to those shown in Figure 1, are arranged as described above and have been assigned the same reference numerals. The bearings 2, 3 and 13 are all fixed into the crank case/cylinder block 20 and the pistons 22 are journalled to the end parts of the rods 9 remote from the arms 8.The engine shown in Figures 2 and 3 operates on the 4 stroke principle with any two pistons linked to a common clutch being on contemporaneous power and exhaust strokes. The camshafts are shown driven from the output shafts, however they could be driven from the crankshaft with advantage. The ignition system may be driven from either the crankshaft, a camshaft or the output shaft.

Figure 4 shows a further embodiment of the present invention.

A free flying piston motor, or the type manufactured by Stelzer Motor GMBH & Co of Frankfurt West Germany is shown at 50. A detailed description of such a motor is given in the November/December 1983 issue of Science and Mechanics. The output from a Stelzer motor is in the form of a reciprocating shaft 51. In accordance with the present invention, the shaft 5 is journalled to the end part of an arm 52, which ars 52, in turn, extends radially outwardly from the outer race 53 of a one way clutch. The inner race 54 of the clutch is fixed in rotation to an output shaft 55.

The clutch is arranged to transmit drive to the shaft 55 only in the direction of arrow D. A linking member 56 extends from the arm 52 to the cranked portion of the crankshaft 57. In use, the output shaft 51 is caused to reciprocate in the directions of arrow C, which in turn causes the arm 52 to reciprocate and drive the output shaft 55 in the direction of arrow D.

Rotation of the crankshaft 57 limits the travel of the output shaft 51 and allows the output shaft 51 to accelerate and decelerate smoothly. The shaft 51 may be linked to a second one way clutch, (not shown), which drives the output shaft 55 in the direction of arrow D, when the shaft 51 is travelling in a direction which does not impart drive through the first one way clutch. Thus the full output of the Stelzer motor may be harnessed and converted into a rotational output.

Claims

1. A power transmission device comprising at least a first reciprocable input shaft, at least a first and a second one way clutch means and, a rotatable output shaft; the arrangement being such that motion of the input shaft in a first direction is transmitted through the first one way clutch to the output shaft, causing the latter to rotate in a first direction, the second clutch being arranged to drive the output shaft in the first direction in response to either, motion of a second reciprocable input shaft in its first direction, or motion of the first input shaft in a second direction; motion of the first input shaft in its second direction is not transmitted through the first one way clutch and motion of a second input shaft in its second direction is not transmitted through the second clutch.

2. A device as claimed in Claim 1 in which the first reciprocal shaft is a toothed rack member reciprocal in a lengthwise direction and arranged to drive the output shaft in unidirectional rotation; through the first one way clutch when moving in the first direction and through the second one way clutch when moving in the second direction..

3. A device as claimed in Claim 1 in which the first reciprocable input shaft is reciprocable in rotation about its axis, in alternate clockwise and anticlockwise directions, and is arranged to drive the output shaft in unidirectional rotation; through the first one way clutch when rotating in a clockwise direction and through the second one way clutch when rotating in an anticlockwise direction,

4. A device as claimed in Claim 1 which comprises at least a first and a second input shaft, both reciprocable in lengthwise directions and both controlled by a .crankshaft arranged to time the reciprocation of said input shafts so that the output shaft is driven substantially continuously.

5. A device as claimed in Claim 4 in which each full stroke of an input shaft causes the output shaft to rotate through an angle of less than 900 and preferably less than 600.

6. A device as claimed in any preceding claim in which each one way clutch comprises inner and outer rotatable members with one way transmission means therebetween, the outer rotatable member being coupled to at least a first input shaft and drive to the output shaft being taken from the inner rotatable member.

7. A device as claimed in Claim 1 which comprises at least first and second input shafts which are journalled to arms extending radially outwardly from an intermediate shaft arranged to be reciprocated in rotation, which intermediate shaft is driveably connected to the one way clutches.

8. A device as claimed in any preceding claim in which the first and second input shafts are the connecting rods of an internal combustion piston engine, the end parts of which connecting rods, remote from the clutches, are driven by the pistons of said internal combustion engine.

9. A power transmission device substantially as hereinbefore described with reference to the accompanying drawings.