GB2291164A

GB2291164A - Parking brake operating mechanism

Info

Publication number: GB2291164A
Application number: GB9410793A
Authority: GB
Inventors: Thomas Tsoi-Hei Ma
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1994-05-28
Filing date: 1994-05-28
Publication date: 1996-01-17
Anticipated expiration: 2014-05-28
Also published as: GB9410793D0; GB2291164B

Abstract

A motor vehicle having a floor tunnel 14 and a hand brake operating mechanism 16 mounted on the floor tunnel 14 adjacent the drivers seat 12. The hand brake operating mechanism 16 has a handle 20 slidable along a track secured to the vehicle floor and a linkage 28 connecting the handle to a remotely located lever system 40, 44 for operating the vehicle parking brake. <IMAGE>

Description

PARKING BRAKE OPERATING MECHANISM The present invention relates to a parking brake operating mechanism for a motor vehicle.

Parking brakes have in the past been foot or hand operated. Foot operated brakes are, as their name implies, applied by foot but they are released by a hand operated catch. Such brakes are practical only for cars with automatic transmission because they are released very suddenly on release of the catch. If the vehicle is fitted with a manual transmission, the driver cannot use clutch control while releasing such a parking brake to prevent the vehicle from rolling backwards during a hill start. Also, for more advanced driving when the parking brake is used to lock and release the rear wheels to induce controlling skidding, such brakes are totally ineffective.

For these reason, it is generally preferred to use a hand operated lever, which gives more control during application and release of the parking brake. Hand brakes have in the past taken one of two principal forms, namely floor mounted and dashboard mounted. Dashboard mounting is again not preferred because with the advent of compulsory seat belts reaching the handle is inconvenient for the driver who has to be careful to lean forward slowly, not to activate the inertia reel mechanism of the belt. Also for advanced driving as described above, dashboard mounting of the parking brake is unacceptable.

At least in Europe therefore, parking brakes are currently almost universally of the floor mounted lever type, being generally mounted between the two front seats of the vehicle. The once used practice of mounting-the lever by the drivers door is not favoured both because it is difficult to reach and because it impedes entry into the passenger compartment.

The most common mechanism is therefore a hand operated lever mounted on what is usually termed the transmission tunnel, even though in many vehicles that are front wheel driven, this tunnel is not present to accommodate the transmission but to house such items as the exhaust pipe, gear shift linkage and the hand brake mechanism. This tunnel in the floor pan, which also serves to improve the stiffness of the vehicle body, is almost universally present in modern vehicles and will hereinafter be termed referred to as a floor tunnel instead of using its more common name.

Hitherto, even with vehicles fitted with a catalytic converter, it has been possible to accommodate all the various necessary components within the floor tunnel by staggering the various elements mentioned above along the length of the tunnel. However, to meet new emission control regulations it is becoming necessary to use ever longer catalytic converters and it is inevitable that the height of the portion of the tunnel on which the hand brake mechanism is mounted must be raised to accommodate the catalytic converter, making it ergonomically inconvenient to operate the hand brake.

The commonly used type of hand brake mechanism comprises a lever pivoted about the centre of a toothed sector that acts as ratchet to lock the lever in any desired position. Operation of such a mechanism requires upwards pivoting of the lever and if the released position is raised because of the increased height of the floor tunnel then the driver has difficulty in pulling the lever up to the desired height to operate the parking brake. Releasing the parking brake is still more inconvenient because the driver is required to pull the lever up still further while pressing on the button that releases the ratchet. The problem is most serious for shorter drivers because their seats are positioned further forward, obliging them to reach backwards for the hand brake lever.

The present invention therefore seeks to provide a mechanism for operating a parking brake that can easily be operated by even short driver in a vehicle having a floor tunnel that is raised to accommodate a relatively long catalytic converter.

According to the present invention, a motor vehicle having a floor tunnel and a hand brake operating mechanism mounted on the floor tunnel adjacent the driver's seat, the hand brake operating mechanism having a handle slidable along a track secured to the vehicle floor and a linkage connecting the handle to a remotely located lever system for operating the vehicle parking brake.

Though the invention was originally designed with the intention of permitting easy use of a hand brake in a vehicle with a raised floor tunnel, it offers ergonomic advantages that commend it even in situations where this problem is not encountered. In particular, the effort required to operate the parking brake is reduced and the operation of the brake is smoother and more progressive. It also offers styling advantages and improved aesthetic appeal as compared with a pivoted lever.

Advantageously, the track and handle assembly includes a releasable one-way clutch device that permits the handle to move freely into the engaged position of the parking brake but only permits movement of the handle in the direction to disengage the parking brake when a catch of the device is released. The one-way clutch device may for example comprise a pawl and ratchet device with a releasable pawl. Other one-way clutch devices may be used, such as those comprising a rolling element wedged between two ramped surfaces.

Because of the- geometry of the parking brake mechanism in the present invention, it is possible to achieve a greater mechanical advantage than with a pivoted lever. A longer stroke is readily achievable with a sliding handle at the point of application of force by the driver, whereas with a lever not only is less movement possible but the driver is required to grip the handle of the lever at a point nearer the fulcrum than the full length of the lever.

This not only enables application of the parking brake with reduced effort but also reduces the force required to release the catch of the one-way clutch device.

The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic representation of the passenger compartment of a motor vehicle, and Figure 2 is a schematic representation of the linkage connecting the hand brake operating mechanism and the brake of the vehicle.

In Figure 1 there is shown the dashboard 10 of a vehicle, a drivers seat 12 and a floor tunnel 14. A hand brake operating mechanism 16 is directly mounted on the floor tunnel 14 and has a handle slidable in the direction illustrated by an arrow in Figure 1.

As shown in Figure 2 the handle 20 of the mechanism 16 has a release button 24 and a downward projection 26 that passes through a slot in the floor tunnel. Beneath the floor tunnel 14 on the underside of the vehicle the projection 26 is connected by a cable 28 passing over three pulleys 30, 32, 34 to a remotely located pivoted lever 40 that operates in the same manner as a conventional pivoted hand brake. In particular the rotation of the lever 40 causes rotation of a cam 44 about an axis 42. A second cable 46 wound around the cam 44 is connected to the parking brake mechanism which may be of the calliper type or the drum brake type.

The handle- 20 slides along a longitudinal track that may incorporate ratchet teeth. A pawl engaging the ratchet teeth moves with the handle 20 and is retractable by depression of the release button 24 on the handle 20.

The principal advantage of the invention resides in the locus of the handle 20, that is to say the path that it traverses between the engaged and the disengaged positions of the parking brake. Whereas the handle 20 follows a convenient linear path easily accessed at all points by a seated driver, the corresponding movement in a conventional hand brake lever would in Figure 1 be an arc terminating close to the shoulder height of the driver on account of the elevated floor tunnel 14. A much greater degree of movement can be realised comfortably in such a geometry thereby allowing a greater mechanical advantage that reduces the effort required to apply the parking brake. The reaction force on the ratchet mechanism is also reduced by the mechanical advantage of the lever 40 so that release of the ratchet mechanism is also correspondingly simplified.

The position of the button in a conventional hand brake lever is usually at the end of the lever, at least in private vehicles and only the thumb can be used to release the brake. It is known that this presents lady drivers in particular with a great deal of difficulty, often resulting in the brake not being fully applied when the vehicle is parked.

The present invention can use a thumb operated button to release the ratchet or other clutch device, but this is not preferred as the handle would then be differently handed for right-hand and left-hand drive vehicles. Instead it is preferred to incorporate a release grip in the handle that can be operated by the palm or the fingers. As a further alternative one may use a sliding collar on the stem of the handle operated in a manner analogous to the reverse gear release found on certain vehicles.

In the present invention it is possible to ensure that the ratchet or clutch are released very easily. If the release is too easy there is a danger of the brake being released either accidentally or by a child left in the vehicle. However the invention gives total freedom in designing the release mechanism to make it possible to ease operation without jeopardising safety and security.

Aside from ease of operation, the design of the parking brake operating mechanism of the invention is more appealing aesthetically and more easily integrated into the centre console because its overall length is less than that of a lever. The mechanism need not extend much further back than the position of the handle when the brake is engaged, allowing an armrest to be positioned behind the hand brake operating mechanism and indeed permitting the operation of the brake while resting on the armrest.

Claims

1. A motor vehicle having a floor tunnel and a hand brake operating mechanism mounted on the floor tunnel adjacent the drivers seat, the hand brake operating mechanism having a handle slidable along a track secured to the vehicle floor and a linkage connecting the handle to a remotely located lever system for operating the vehicle parking brake.

2. A motor vehicle as claimed in claim 1, wherein the track and handle assembly includes a releasable one-way clutch device that permits the handle to move freely into the engaged position of the parking brake but only permits movement of the handle in the direction to disengage the parking brake when a catch of the device is released.

3. A motor vehicle as claimed in claim 2, wherein the oneway clutch device comprises a pawl and ratchet device with a releasable pawl.

4. A motor vehicle having a hand brake operating mechanism constructed arranged and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.