AU2001237080A1 - Stabilizer unit - Google Patents

Description

STABILIZER UNIT

Field of the Invention

THIS invention relates to a stabilizer which is adapted to be coupled between a towing vehicle a towed vehicle referred to herein as "a trailer".

Description of Prior Art

Single axled and closely spaced double/triple axled trailers and caravans attached to

towing vehicles generally have poor stability, this being characterized by the towing

vehicle changing direction without steering input. The stability worsens as the weight

of the trailer relative to the towing vehicle increases and as the towing speed increases.

A known conventional stabilizer for a towing vehicle and trailer, comprises a strut

including a pivot point at the tow hitch to enable the strut to move angularly about a

generally vertical pivotal axis in accordance with angular movement between the

towing vehicle and trailer. Such arrangements include friction means to resist angular

movement of the struts. A disadvantage of such arrangements is that whereas the

friction means acts to resist angular movement between the towing vehicle and trailer,

once angular movement have occurred, reverse movement to align the towing vehicle and trailer is also resisted. A further shortcoming of this type is that it does not

prevent instability. It allows it to start and then dampens the motion to contain the

instability so that it does not build up to unmanageable proportions.

A second known type of device used to improve the stability of a combination is of a

geometric type. This type of device is positioned between the trailer and tow vehicle

and by a system of levers moves the "hinge point" (in the horizontal plane) between

the trailer and tow vehicle to a point closer to the rear axle of the tow vehicle (for

small angular deflections). This type is a better stabilizer than the friction damper type

but it has two major drawbacks, namely, it is a precision device and is expensive to

build; and it has to handle all the towing forces acting between trailer and towing vehicle.

Object of the Invention

It is an object of the present invention to provide a novel stabilizer unit which will

overcome, or at least improve on the above mentioned disadvantages.

Summary of the Invention

According to the invention such a stabilizer comprises an elongate arm member adapted to extend between a towing vehicle and a trailer, the arm member including

a first arm section and a second arm section pivotally coupled to one another to permit

relative angular movement between the arm sections, a cam formation provided on one

arm section, in engagement with a follower formation provided on the other arm

section, biasing means for biasing the cam formation and follower formation towards

one another, the arrangement being one wherein relative angular movement between

the first and second arm sections is resisted by the movement of the follower formation

on the cam formation against the action of the biasing means, said biasing means being

mounted on the arm member to act in a longitudinal direction relative thereto.

Preferably, the biasing means will be in the form of a compression spring, gas strut

or the like.

Further according to the invention, the cam formation is in the form of a concave

formation and the follower in the form of a roller disposed within the concave

formation, and biased so that movement of the follower out of the concave formation

will be resisted by the biasing means. Preferably the concave formation will be in the

form of a generally V-shaped formation, which has an included angle selected to

provide a centering force of between 300 and 400, preferably 350Nm.

Also according to the invention the one end zone of the arm member is slidingly

mounted on the trailer or towing vehicle to permit movement of the trailer towards and away from the towing vehicle, for example during braking, while the other end zone

is rigidly secured to the towing vehicle or trailer respectively. It is envisaged that

mounting means for slidingly mounting the arm member will comprise a cradle

formation which slidingly receives an end zone of the arm member. With such an arrangement, the arm member could be resiliently flexible in a vertical plane, and

tensioned against such flexing in a vertical plane, in order to resist pitching movement

between the towing vehicle and the trailer.

Also according to the invention, the biasing means acts on a transversely disposed

cantilever which extends from the arm member whereby the arm member is flexed

downwardly in a vertical plane into engagement with the cradle attachment.

Further according to the invention a dampening means is provided for dampening the

movement of the cam follower. The invention envisages that such dampening means

could be incorporated in the biasing means.

Still further according to the invention the stabilizer includes activating means for

activating or deactivating the biasing means. Thus in a deactivating state, the biasing

means will be withdrawn so that the cam formation does not act against the movement

of the cam follower, and the arm member itself will be in an unflexed condition. The invention further provides for the cam formation or the cam follower to include

outwardly extending shoulder formations which are adapted to be engaged by the cam

follower or the cam formation respectively, or an extension thereof, when the cam

follower moves out of the concavity of the cam formation. In this way the stabilizer

is de-activated when angular movement between the first and second arm sections

exceed a predetermined value.

Brief Description of Drawings

In order further to illustrate the invention an embodiment thereof is described

hereunder purely by way of example with reference to the accompanying drawings

wherein:

Figure 1 is a schematic perspective view of a stabilizer unit in accordance

with the invention;

Figure 2 is a schematic plan view of the stabilizer unit in Figure 1 ;

Figures 3 & 4 are partially exploded plan views of the stabilizer unit in Figure

1 acting against bending movements in opposite directions; Figure 5 is a p-itially exploded plan view of the stabilizer unit in Figure

1 in a de-activated position;

Figures 6 & 7 are parts of exploded schematic perspective views of the stabilizer unit in Figure 1 ; and

Figure 8 is a schematic elevation of the stabilizer unit in Figure 1 in position between a towing vehicle and a trailer.

Detailed Description of Drawings

Referring to the drawings, a stabilizer unit in accordance with the invention comprises

an arm member 10 having a first arm section 11 and a second arm section 12 pivotally

coupled at 13. In the arrangement shown in the drawings, the first arm section 11 is

adapted to be secured to the towing vehicle 14, while the second arm section 12 is slidingly mounted on the trailer 15, Figure 8. Alternatively, if space permits, the first

arm section 11 could be slidably secured to the towing vehicle 14, while the second

arm section 12 could be fixed to the trailer 15. In use, angular movement between the

towing vehicle 14 and the trailer 15 is resisted by the stabilizer unit, and preferably

also dampened. It has been found that such action by the stabilizer unit tends to

minimize continuous swaying between the towing vehicle 14 and trailer 15. The arm member 10 is further resiliently flexible as described in more detail below, and exerts

a downward force on the trailer to resist pitching movement between the towing

vehicle 14 and trailer 15; that is pivoted movement in a vertical plane between the towing vehicle 14 and trailer 15.

The stabilizer unit further includes a generally V-shaped cam formation 16 which

moves in conjunction with the second arm section 12, and a cam follower formation

17 which is located within the V-shaped cam formation 16, and which moves in

conjunction with the first arm section 11, and biasing means 18 which urges the cam

formation 16 towards the cam follower 17 with a force of around lOOKg force

(lOOONm). With this arrangement therefor, relative angular movement between the

first arm section 11 and the second arm section 12 about the pivot point 13, will cause

relative angular movement between the V-shaped cam formation 16 and the follower

formation 17, causing the latter to move in a direction out of the concavity of the V-

formation, Figures 3, 4, against the action of the biasing means 18. The biasing

means 18 thus tends to resist movement of the cam follower 17 out of the concavity

of the V-formation 16, and consequently, resist angular movement between the towing

vehicle 14 and the trailer 15. In effect therefor, the stabilizer unit tends to align the

towing vehicle 14 and the trailer 15. The invention provides for the V-formation to

have an included angle of around 30° which will provide a centering force of around

350Nm. In the arrangement illustrated, the biasing means 16 comprises a gas strut in the form

a pneumatically charged piston and cylinder ram device which preferably includes a

dampener. Thus the one end 18a of the cylinder 18 is secured to the second arm

section 12, while a moveable connecting rod 18b coupled to the piston, not shown, is

secured to the cam formation 16. Clearly variations are possible in this regard, and in an alternative arrangement, not shown, the biasing means could comprise a compression spring and/or a separate dampener.

Preferably the stabilizer unit will include means 19, Figure 7, for releasing the force of the biasing means 18, for example, to facilitate hitching and unhitching of

stabilizer. Such a release mechanism 19 could for example, comprise second degree

lever having a fulcrum at 19a mounted on an end block 18c which engages the end

zone 18a of the cylinder 18. The lever 19 acts on the connecting rod 18b of the

cylinder 18 via parallel links 50 to withdraw the connecting rod 18b and the cam

formation 16. Preferably the lever 19 will be movable between a released position

wherein the cylinder 18 is operational to an over centre withdrawn position, so that

the lever 19 will remain in such withdrawn position unless released. Preferably a

handle 19b, Figure 1, for operating the lever 19 will be removable and could for

example engage the lever 19 in spigot and socket fashion as illustrated. The links 5 engage the lever 19 at 19b by means of a slot 50a which allows for movement of the cam formation 16 when the stabilizer is operational.

A further feature of the invention provides for the V-shaped cam formation and

follower formation to be rendered inoperative when the follower moves out of the V-

formation as shown in Figure 5. In the arrangement illustrated in Figure 5, shoulder formations 20 are provided on a bracket 21 of the follower 16, such shoulder

formations 20 being engaged by an extension 22 of the cam formation 16 when the

follower 17 moves out of the V-formation 16.

An alternative arrangement, not shown, the shoulder formations 20 could be provided

at each side of the V-formation 16, so that the follower 17 will engage these when it

moves out of the V-formation 16. It is envisaged that the shoulder formations 20 will

be curved at approximately the same radius as the extension 22 subscribes about the pivot point 13, so that there will be no nett moments of force acting about the pivot

point 13 which would move the first arm section 11 and the second arm section 12 into

or out of alignment.

A further feature of the invention provides for the arm member 10 to be of a generally

Z-shaped configuration which allows the first arm section 11 to be secured to the towing vehicle 14 adjacent a towing hitch 23 thereof, and which permits the trailer 15

to be secured to the second arm section 12 so that the latter is generally parallel to the

longitudinal axis of the trailer 15. This feature permits the trailer 15 to move towards

the towing vehicle, for example during braking. This permits the use of an overrun brake system, not shown, for the trailer, without influencing the effectiveness of the

stabilizer of the invention. In this regard, the invention also provides for the biasing

means 18 to be mounted on the arm section 12 as previously described, so that it acts

in a longitudinal direction relative to the centre of the cam formation 16. The action

of the biasing means 18 is therefor not influenced by movement of the trailer 15 or the

towing vehicle 14.

Variations are possible with regard to means for securing the arm member 10 of the

stabliser unit to the towing vehicle 14. In the arrangement illustrated in Figure 1, such

means comprises a socket formation 24 which is secured to the towing vehicle 14 by

means of a bracket 25, and into which the end of the first arm section 11 is a snug fit.

Preferably locking means, for example, in the form of a threaded bolt 26 or the like

will be provided for locking the arm section 11 in the socket 24.

Variations are likewise possible with regard to the means for securing the second arm

section 12 to the trailer 15, and in the arrangement illustrated, such means comprises a generally U-shaped cradle formation 21 within which the arm section 12 is slidingly receivable. Thus the slidable mounting of the arm section 12 to the trailer 15 will

permit relative angular movement between the towing vehicle 14 and trailer 15.

It is a further feature of the invention that the arm member 10 will be resiliently

flexible in a vertical plane, and for this purpose the arm section 12 could for example

be in the form of a leaf spring. With such an arrangement therefor, since the arm

member 10 is rigidly secured to the towing vehicle 14 as previously described, a

downward force could be applied to the trailer 15 by means of the resilient nature of

the arm member 10. Such downward force will act to resist pitching or pivotal movement in a vertical plane between the towing vehicle 14 and the trailer 15. In

order further to enhance this anti-pitching action of the arm member 10, the invention

provides for the biasing means 18 to act on a cantilever 40, Figure 7, which extends

laterally upwardly from the arm section 12, so that the longitudinal force of the biasing

means 18 will cause a downward flexing of the arm section 12 to increase the downward force thereof on the trailer 15.

From a construction point of view, the V-shaped cam formation 16 is housed within

a U-shaped bracket defining two parallel plate sections 27, and a base 28 which is

secured to the gas cylinder 18 by means of a lug 29 which mates with a corresponding

device 30 at the end 18b of the cylinder 18, Figure 7. The one plate member 27, also

defines the extension 22 at the free end thereof, which is adapted to engage the shoulder formations 20 as described above. The U-shaped bracket is movable in order

to move the V-shaped cam formation 16 between its operative and inoperative

position, and is mounted between a pair of opposed trough-like guides 31 which house

rollers 32 mounted on opposed sides of the bracket by means of a shaft 33. The upper

guide 31 is pivotally secured about the pivot point 13, while the lower guide 31 is secured to the second arm section 12.

The cam follower 17 is mounted between a fork comprising two spaced plate members

34 which are secured to the first arm section 11. It will be noted that the shoulder

formations 20 are mounted on the upper fork section 34.

Doubtless other variations of the invention in detail exist without departing from the

principles set out in the consistory clauses.

It will be understood by persons skilled in the art that the stabilizer of the invention provides a relatively compact means for biasing a towing vehicle and a trailer into

alignment, and also provides an anti-pitching effect. The dampening effect of the

stabiliser acts to dampen angular movement between the towing vehicle and trailer,

thus reducing swaying movement between these.

Claims (16)

Claims

1. A stabilizer comprising an elongate arm member adapted to extend between a

towing vehicle and a trailer, the arm member including a first arm section and

a second arm section pivotally coupled to one another to permit relative

angular movement between the arm sections, a cam formation provided on one arm section, in engagement with a follower formation provided on the other

arm section, biasing means for biasing the cam formation and follower

formation towards one another, the arrangement being one wherein relative

angular movement between the first and second arm sections is resisted by the

movement of the follower formation on the cam formation against the action of the biasing means, said biasing means being mounted on the arm member.

2. The stabilizer according to claim 1 wherein the cam formation is in the form

of a concave formation and the follower in the form of a roller disposed within

the concave formation, and biased so that movement of the follower out of the concave formation will be resisted by the biasing means.

3. The stabilizer according to claim 1 or claim 2 wherein the cam formation is in the form of a concave formation of generally V-shaped configuration, with the included angle of thi V-shape being selected to provide a centering force of between 300 to 400Nrn.

4. The stabilizer according to claim 3 wherein the included angle of the V-shape is in the order of 30° .

5. The stabilizer according to any one of claims 1 to 4 wherein one end zone of

the arm member is slidingly mounted on the trailer or towing vehicle, while

the other end zone thereof is rigidly secured to the towing vehicle or trailer respectively, to permit movement of the trailer towards and away from the

towing vehicle.

6. The stabilizer according to claim 5 wherein the one end zone of the arm member which is slindingly mounted on the trailer or towing vehicle is

disposed parallel to the longitudinal axis of the trailer or towing vehicle.

7. The stabilizer according to claim 6 wherein the arm member is of a generally

Z-shaped configuration in the horizontal plane with at least one end zone of the

Z-shaped configuration being disposed parallel to the longitudinal axis of the

trailer or towing vehicle.

8. The stabilizer according to any one of claims 1 to 7 wherein the arm member

is resiliently flexible in a vertical plane and is tensioned against flexing in a

vertical plane, in order to exert a downward force on the trailer or towing

vehicle, in order to resist pitching movement between the towing vehicle and

the trailer.

9. The stabilizer according to claim 8 wherein the biasing means mounted on the

arm member acts on a transversely extending cantilever extending from the

arm member, whereby the arm member is flexed downwardly in a vertical plane to exert a downward force on the towing vehicle or trailer.

10. The stabilizer according to claim 5 wherein the mounting means for the

slidingly mounting one end zone of the arm member comprises a cradle

formation which is slidingly received in the end zone of the arm member, and

which is adapted to receive a downward force exerted by the arm member.

11. The stabilizer according to any one of claims 1 to 10 wherein a dampening

means is provided for dampening the movement of the cam follower.

12. The stabilizer according to claim 11 wherein the dampening means is

incorporated in the biasing means.

13. The stabilizer according to any one of claims 1 to 12 including activating

means for activating or deactivating the biasing means, such activating means

comprising a lever which is adapted to compress the biasing means when moved in one direction, and to release the biasing means when moved in the reverse direction.

14. The stabilizer according to any one of claims 1 to 13 wherein the concave cam

formation or the cam follower include outwardly extending shoulder

formations which are adapted to be engaged by the cam follower or the cam

formation respectively, or an extension thereof, when the cam follower moves

out the V-formation.

15. The stabilizer according to claim 14, the cam follower moves out of the V-

formation when the first arm section and second arm section move pivotally

relative to one another through 15° in either direction.

16. A stabilizer substantially as herein described and exemplified with reference

to the accompanying drawings.