GB2152157A

GB2152157A - Reversible unidirectional ratchet drive

Info

Publication number: GB2152157A
Application number: GB08419527A
Authority: GB
Inventors: Walter Arpert; Ulrich Thalmann
Original assignee: MUEHLHAUSEN KINDERFAHRZEUGE
Current assignee: MUEHLHAUSEN KINDERFAHRZEUGE
Priority date: 1983-12-30
Filing date: 1984-07-31
Publication date: 1985-07-31
Also published as: CS254143B1; GB2152157B; BE901384A; DE8421228U1; HU197786B; NL8403343A; ATA232684A; YU167584A; DD230720A3; DE3426108A1; GB8419527D0; HUT36234A

Abstract

A freewheel consists of a drive disc (4) provided with oppositely directed ratchets (5) which engage with recesses (13) in a toothed driven wheel (3) to drive the wheel respectively in opposite directions with freewheel action. A control spring (9) extends between the toothed wheel (3) and the drive disc (4), and includes an opening through which the ratchets (5) can protrude into the recesses (13). The control spring (9) is frictionally engaged by a brake arrangement including brake springs (12) mounted on a brake disc (8). Changeover of the drive direction can occur when the freewheel is stationary and then the reversal of the drive direction causes rotary movement of the control spring (9) to lift the engaged ratchet (5) from the recess (13) to an inoperative position and allow the other ratchet to protrude through the opening into a recess (13). The freewheel may be used in a child's vehicle. <IMAGE>

Description

SPECIFICATION Reversible unidirectional ratchet drive The present invention is concerned with a double-acting freewheel, especially but not exclusively for children's vehicles.

A double-acting freewheel is known from German Democratic Republic Patent Specification No. 139,154 which has two oppositely directed ratchets to provide freewheel action in opposite rotary directions. A ratchet locking mechanism is provided so that only one ratchet is operative at a time. More particularly, a toothed wheel or notched star is mounted on a rotary shaft, the teeth of the notched star defining recesses. A drive disc is provided with oppositely directed ratchets which are urged to engage in the recesses by associated pressure springs. The notches are disposed in recesses in the drive disc. A spacer is arranged beside the notched star together with a fixed brake disc. Pre-stressed control springs mounted in the brake disc have portions which project into the recesses of the drive disc.The control springs act upon rotary movement of the drive disc as control elements, such that one of the ratchets is pushed over the projection of the control springs as far as the recesses in the drive disc receiving the ratchets permit. In this way, depending upon the direction of rotary movement, one ratchet is pressed back into the drive disc and remains ineffective, whereas the other ratchet takes over the function of the freewheel or power transmission. Upon further rotary movement of the drive disc, the control springs are taken along and slide into the brake disc, whereas, in the case of freewheel action, the position of the control spring is again fixed by the brake disc.

In the case of a change of direction of rotation of the drive disc, the position of the projections of the control springs is so changed that a different one of the ratchets engages in one of the recesses of the notched star.

A disadvantage of this known double-acting freewheel is that a reversal of the freewheel action can take place immediately after the change of the direction of rotation of the drive which can be dangerous, especially in the case of children's vehicles, which, for example, when travelling downhill could not be rectified.

It is an object of the invention to provide a double-acting freewheel in which such an immediate change of the direction of drive is prevented to reduce risk of accident, particularly for children's vehicles.

According to the present invention there is provided a double-acting freewheel comprising: an annular drive member; a rotary driven member; means defining in said drive and driven members a recess and first and second ratchets arranged to engage the recess respectively to couple torque with a freewheel action from the drive member to the driven member in opposite rotary drive directions; an annular control member mounted for rotation between said drive and driven members, the control member including an opening through which the ratchets can engage the recess; and braking means arranged frictionally to engage the control member in such a manner that upon changeover of rotary direction of the drive member with said driven member substantially stationary, the control member lifts one of the latches from the recess and permits the other latch to engage the recess.

The opening in advantageously provided in the region of the open ends of the control spring.

It is preferable that the ends of the brake springs engage in pockets provided in the brake disc.

By means of the solution according to the invention, a long reversal path is achieved which prevents the spontaneous change of the drive direction, as well as the possible danger of accident involved therewith, and ensures a dependable and simple employment, especially in the case of use on children's vehicles.

In order that the invention may be more fully understood, an embodiment thereof will now be described by way of example with reference to the accompanying drawings wherein: Figure 1 is a side view in section of a double-acting freewheel according to the invention; and Figure 2 a front view of the double-acting freewheel shown in Figure 1.

A carrier flange 2 is fixedly mounted on a rotary shaft 1. A toothed wheel 3 referred to herein as a notched star, provided with annular recesses 1 3 between its teeth, is attached by means of rivets 10 to the flange 2. A drive disc 4 is provided with oppositely directed ratchets 5 in recesses 1 5. Associated pressure springs 6 urge the ratchets to drivingly engage recesses 1 3 with a freewheel action in opposite directions. A spacer 7, as well as a cover plate 11 are attached by the rivets to the flange 2. An annular control spring 9 having open ends surrounds the notched star 3. The open ends of spring 9 define a recess 1 4 for providing an opening through which the ratchets 5 individually can enter the recesses 1 3 of the notched star 3.

Three, pre-stressed brake springs 1 2 are provided between a brake disc 8 and the control spring 9, the spring 1 2 extending around substantially the whole circumference of the control spring. The ends of the brake springs 1 2 are received in the pockets 1 6 provided in the brake disc 8. The brake springs 1 2 frictionally engage the control spring 9.

When the drive disc 4 is driven, both ratchets 5 slide over the control spring 9 held by the brake disc 8 and the brake spring 1 2.

When the ratchet 5 mounted in the direction of the driving movement reaches the recess 1 4 of the control spring 9, it engages through this into the recess 1 3 of the notched star 3, and the oppositely mounted ratchet 5 remains in the recess 1 5 of the drive disc 4. If the drive disc 4 is stopped, then the shaft 1 with the carrier flange 2, the notched star 3, the spacer 4 and the cover plate 11, turns further in the driving direction and the freewheel takes place via the ratchet 5 in engagement.

The brake springs 1 2 act brakingly on the control spring 9. After the stopping of all parts in working connection, the drive in the opposite direction can advantageously take place, whereby the ratchet 5 hitherto in engagement with a recess 1 3 is lifted by the control spring 9 from the notched star 3 into the recess 1 5 of the drive disc 4 and the other ratchet 5 engages via the recess 14 of the control spring 9 into the recess 1 3 of the drive disc 4. By means of this arrangement, the lengthening of the reversal path is ensured and a directly spontaneous change of the drive direction is no longer possible so that the previously existing possible source of accident is excluded.

1. A double-acting freewheel comprising: an annular drive member; a rotary driven member; means defining in said drive and driven members a recess and first and second ratchets arranged to engage the recess respectively to couple torque with a freewheel action from the drive member to the driven member in opposite rotary drive directions; an annular control member mounted for rotation between said drive and driven members, the control member including an opening through which the ratchets can engage the recess; and braking means arranged frictionally to engage the control member in such a manner that upon changeover of rotary direction of the drive member with said driven member substantially stationary, the control member lifts one of the latches from the recess and permits the other latch to engage the recess.

2. A freewheel according to claim 1, wherein the driven member comprises a wheel with teeth defining said recesses, and said drive member comprises an annular disc coaxial with and surrounding said wheel, the disc carrying said ratchets.

3. A freewheel according to claim 2, wherein the control member comprises an annular control spring surrounding toothed wheel, the opening being defined between the ends of the spring.

5. A freewheel according to claim 3, wherein said braking means includes a brake disc coaxial with the toothed wheel and axially spaced therefrom, the brake springs having their ends received in pockets in the brake disc, the brake springs frictionally engaging the control spring.

5. A freewheel according to claim 4, wherein the brake springs are pre-stressed.

6. A double-acting freewheel substantially as herein described with reference to the accompanying drawings.

7. A child's vehicle including a doubleacting freewheel according to any preceding

Claims

claim. 8. A double-acting freewheel which is formclosedly or positive fixed by means of a carrier flange on to a drive wheel or on to a drive shaft on which is provided a notched star having recesses, on which the drive disc is rotatably mounted, whereby in the drive disc ratchets impinged against in recesses by pressure springs are counter-mounted and beside the drive disc is provided a fixed brake disc and between the brake disc and a spacer. lying next to the notched star, between the notched star and the drive disc is so arranged a projecting control spring that, in each case, only one of the ratchets is in operational connection, especially for children's vehicles, characterised in that the control spring is open and encircles the notched star and has a recess, extending in the region of the notched star, corresponding at least to the breadth of the recess of the notched star, through which recess the ratchet engages in the notched star, and also in the region of the brake disc and the spacer there are provided between the brake disc and the control spring one or more brake springs extending over the whole circumference. CLAIMS Amendments to the claims have been filed, and have the following effect: Claims 1 to 4 above have been deleted or textually amended. New or textually amended claims have been filed as follows:

1. A double-acting freewheel comprising: an annular drive member; a rotary driven member; means defining in said drive and driven members at least one recess, and first and second ratchets respectively arranged to engage a said recess to couple torque with a freewheel action from the drive member to the driven member in opposite rotary drive directions; an annular control member mounted for rotation between said drive and driven members, the control member including a single opening through which the ratchets can en gage a said recess; and braking means arranged frictionally to engage the control member in such a manner that upon changeover of rotary direction of the drive member with said driven member substantially stationary, one of the ratchets is lifted from the opening of the control member and the drive member rotates such that the other ratchet engages a said recess through said opening.

2. A freewheel according to claim 7, wherein the driven member comprises a wheel with teeth defining a plurality of said recesses, and said drive member comprises an annular disc coaxial with and surrounding said wheel, the disc carrying said ratchets.

3. A freewheel according to claim 2, wherein the control member comprises an annular control spring surrounding the toothed wheel, the opening being defined between the ends of the spring.

4. A freewheel according to claim 3, wherein said braking means included a brake disc coaxial with the toothed wheel and axially spaced therefrom, and brake springs having their ends received in pockets in the brake disc, the brake springs frictionally engaging the control spring.