GB1586635A

GB1586635A - Spring-loaded brake actuator device

Info

Publication number: GB1586635A
Application number: GB1302/78A
Authority: GB
Original assignee: KNORR BREMSE GmbH; Knorr Bremse AG
Current assignee: KNORR BREMSE GmbH; Knorr Bremse AG
Priority date: 1977-01-25
Filing date: 1978-01-12
Publication date: 1981-03-25
Also published as: IT7847520A0; FR2378208A1; DE2702840A1; IT1103570B; SE7800850L; BR7800403A

Description

(54) SPRING-LOADED BRAKE ACTUATOR DEVICE (71) We,KNORR-BREMSE GmbH, Moosacher Strasse 80, D-8000 Munchen 40, Federal Republic of Germany, and a German company do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to an actuator device adapted for coupling with an operating member of a brake system and operable in use under spring action to effect application of the brake system and when supplied with pressure medium to effect release of the brake system.

It is known to use spring-loaded cylinders as actuator devices for brake systems and, when employed with motor vehicle brakes, they have the task of actuating the brake cylinder mechanism in the event of a reduction in the supply pressure. In this manner, a vehicle can be slowed down, and retained by means of the brake. Additionally, it is possible to brake the vehicle reliably, even when there develops a defect in the brake line i.e. in the supply pressure. However, it is desirable for various reasons to be able to release once again (where necessary) the brakes without any considerable cost outlay, so as to be able to tow-away the vehicle for the purpose of repair.In known spring-loaded piston - cylinder devices, a release device comprises a screw spindle which is arranged in a sleeve in the interior of a spring chamber, the screw spindle co-operating with a threaded sleeve secured against rotation in such manner that, in the event of rotation of the screw spindle, axial displacement of the threaded sleeve takes place. One end of the threaded sleeve carries a stop co-operating with a counter-stop secured to the inner side of the piston.

In the case of this release device, it is considered to be disadvantageous that, for releasing or pre-tensioning the spring-loaded means, numerous rotations of the screw spindle are required. Before the spring-loaded means is once again ready for operation, furthermore, it is necessary to screw-back into its lowest position a transverse pin pushed through the threaded sleeve and serving as a stop. For this purpose, again, numerous rotations are necessary (see German Utility Model No. 7'118 947).

According to the invention, there is provided an actuator device adapted for coupling with an operating member of a brake system and operable in use under spring action to effect application of the brake system, and when supplied with pressure medium to effect release of the brake system, in which the actuator device comprises:: a cylinder; a piston slidably mounted in said cylinder and held against rotation relative to the cylinder; a pressure chamber defined in said cylinder on one side of said piston to receive a supply of pressure medium for urging the piston in a brake-release direction; spring means arranged in said cylinder and engaging said piston to urge the latter in a brake-application direction; a hollow piston rod connected to said piston so as also to be held against rotation relative to the cylinder; a connector sleeve housed within and connected to said piston rod, said sleeve being adapted for connection to an operating member of a brake system;; a connector pin extending transversely through said sleeve to interconnect the sleeve and the hollow piston rod, the connector pin being adjustable between a first connecting mode in which the pin is operable to transmit linear thrust between the piston rod and the sleeve and a second connecting mode in which the pin allows relative longitudinal movement to take place between the piston rod and the sleeve; an adjustment spindle in said hollow piston rod and connected to said connector pin, said spindle being pivotable about is longitudinal axis in order to pivot the connector pin between its first and second connecting modes; and means biasing the spindle so that the latter urges the connector pin to occupy its first connecting mode.

According to an advantageous embodi ment of the invention, release of the brake may be effected with a single manipulation if a key or similar tool is applied to an end of the adjustment spindle projecting from the brake cylinder, and the spindle is rotated.

This rotation is effected against the biasing means e.g. a torsion spring, and is required only on an arc of approximately 600, until the connector pin (which in the normal case establishes the positive connection between the piston rod and the sleeve) pivots into the second connecting mode. In this position, the sleeve and the brake operating member when coupled therewith are able to move relative to the piston rod in the longitudinal direction, i.e. the brake is released.After repairs have been effected and the piston is subjected to the action of pressure medium, the piston displaces the piston rod connected to it until the connector pin, which is initially guided in a longitudinally extending limb of an L-shaped slot in the second connecting mode, is snapped by the biasing means into a perpendicularly extending limb of the Lr shaped slot so as to take up the first connecting mode. Thus, no rotating or restoring movement of hitherto conventional type is necessary in order to transfer the brake once again into its functional condition.

The release arrangement must be considered to be inexpensive also in the constructional sense, since it requires no fine machining of the elements required. Furthermore, the elements can be replaced quite readily and without any great expenditure, if such should be necessary.

One embodiment of the invention will now be described in detail, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a longitudinal section of a spring-loaded cylinder of an actuator device according to the invention; Figure 2 is a partial plan view taken in the direction of the arrow II in Figure 1; and Figure 3 is a sectional view taken along the line III-III in Figure 1.

Referring to Figure 1, this Figure shows a brake cylinder 1 in the form of a pulling spring-loaded cylinder; the brake cylinder has a fluid pressure medium chamber 3 and a spring chamber 5. The pressure chamber and the spring chamber are separated from each other by a piston 7,thepiston being connected with a hollow piston rod 9 which extends displaceably through a base 11, designed as a cover, of the brake cylinder. Disposed within the spring chamber 5 is a spring 13 bearing, at the left-hand end in Figure 1, against the base 11 and, at the right-hand end, against the piston 7.Into the chamber 3 there is taken a pressure air connection 15, by means of which pressure air is introduced into the pressure chamber for displacing the piston 7 towards the left, as shown in Figure 1, for the purpose of a release operation described hereinbelow.

Out of the piston rod 9 extends a piston rod 17 which is connected to an operating member of braking means to be actuated, thus for example to a wedge-spreading brake, etc., of a motor vehicle. Normally, the piston rod 17 is non-positively connected with the piston rod 9.

Thus, the piston rod 17 has, at its end located within the piston rod 9, a head 19 retained within a connector sleeve in the form of a bush 21 which is rotatable relative to it. The bush 21 is arranged within the piston rod 9 to be diaplaceable relative thereto and there extends through it, at its right-hand end according to Figure 1, a radially extending connector pin 23. The pin extends through bores formed in the walls of the bush 21. The ends of the pin 23 extend through the walls of the piston rod 9, i.e. they are normally guided in a short limb 25 of an Shaped slot 27 (when the connector pin occupies the first connecting mode) the latter having a long limb 29 (Figure 2) which extends at right angles from the short limb 25 and in the direction towards the base 11 of the brake cylinder 1.Provided at the outer peri phery of the piston rod 9 are a stop ring 1 and a reinforcing ring 33. In the zone of the long limb 29 of the L-slot, the above-mentioned rings are formed with apertures (as shown in Figure 2). In this manner, the pin 23 is able, in the manner described hereinbelow, to move also within the long limb 29 relative to the latter (when the connector pin occupies a second connecting mode).

The pin 23 is, within the bush 21, guided in a fork end 35 of an adjustment spindle 37 extending from the pin 23 through the piston rod 9 and extending through an end face 39 of the brake cylinder in sealed fashion.

Provided at the outer end of the spindle 37 is a connecting member to receive a manually actuable tool, thus for example a hexagon 41 secured by means of a notched pin 43. Relative to the pressure chamber 3, the spindle is sealed in the zone of the end face by a packing 45. The spindle is surrounded by biasing means in the form of a torsion spring 47, one end of which is secured to the spindle, whereas the other end is secured to the endface of the brake cylinder 1. The torsion spring is installed under a pre-determined degree of bias, in such manner that the spindle is biased in a direction of rotation whereby the pin 23 is always urged into abutment with the end of the short limb 25 of the slot. Thus, rotation of the spindle is transmitted via the forked end 35 to the pin 23 (guided between the limbs of the fork), i.e. rotations of the spindle 37 exerted via the hexagon 41 are imparted to the pin 23. The fork end receiving the pin 23 can be designed to be closed, as apparent from the dashed line in Figure 2. Thus, the pin is able to move within a slot 48 defined by the forked end 35, closed on both sides, as is discussed in detail hereinbelow. In order to guarantee guiding of the pin 23 in its position, preferably a guide bush 49 and an O-ring 51 are provided (Figure 3).

In order to secure the arrangement comprising the piston 7 and the spring 13 against rotation relative to the brake cylinder 1, there are provided securing wedges 53 or 55 which are secured to the piston 7 and to the base 11 respectively and engage into an associated recess formed in the adjacent side of the spring 13, in such manner that the piston is non-rotatably retained in the brake cylinder.

The mode of operation of the high-speed or emergency releasing device is as follows: During normal operation, braking is effected with the aid of the spring 13, i.e. the brake cylinder is designed as a pulling cylinder, in such manner that the piston rod 17 actuates the braking means if it is displaced towards the right according to Figure 1 by the piston, via the hollow piston rod, the pin 23 and the bush 21. During this movement, the pin 23 is in the position shown in Figure 2. Due to the bias imparted on installing the torsion spring 47, the latter has the tendency to rotate the spindle 37 in that direction in which the pin 23 travels upwardly according to Figure 2.

In this manner, the pin always bears at the end of the short limb 25 of the L-slot 27. If the piston 7, with the chamber 3 vented and with the spring 13 becoming effective, effects the movement directed towards the right in Figure 1, then the piston rod 9 exerts a pull on the pin 23, the piston rod carrying for this purpose the reinforcing ring 33. The pin entrains the sleeve 21 which extends through it radially, the left-hand end in Figure 1 of the sleeve exerting a pull at the head 19 of the piston rod 17, in such manner that the piston rod 17 acts upon the braking means.

For releasing the brake, a pressure medium, usually pressure air, is introduced into the chamber 3 via the pressure air connection 15.

The pressure chamber is, in the zone of the spindle emergence, with the aid of the packing 45 and relative to the interior of the piston tube, sealed-off by a packing. The pressure building-up in the chamber 3 acts on the piston 7 and displaces it towards the left as shown. The piston rod 17 is displaced towards the left by a recall spring (not shown) provided in the brake or the like mechanism, until the brake is completely released. The pin 23 can also, due to abutment with the walls of the short limb 25 of the Lslot, be displaced into a released position.

During this movement directed towards the left, the spring 13 is compressed in known manner, there being provided for the spring chamber 5 (the volume of which is reduced) venting means or the like (also known).

If the pressure means connection with the pressure air connecting means 15 is, when the vehicle is travelling (brake released) damaged or rendered non-fluid-tight, then the pressure in the cylinder chamber 3 is reduced, i.e. the brake becomes automatically operative and brakes the vehicle in accordance with the now extending spring 13.

Iri order to be ablebnce again to release "the, brake which has been operated in this manner following a failure in the pressure supply, a tool (for example a key) is applied to the hexagon 41 and the hexagon (and with it the spindle 37) is rotated against the bias of the torsion spring 47. This means that the pin 23 is, due to the spindle 37 connected with it, displaced downwardly as seen in Figure 2 and passes into the zone of the long limb 29 of the Lslot 27.

The remaining force of the spring 13 now becomes inoperative, i.e. the spring presses the piston and the piston rod into the abutment position at the end face 39 of the brake cylinder. The pin 23 does not accompany this movement, since it is disposed within the long limb 29. Since the non-positive connection between the piston tube 9 and the piston rod 17 is interrupted, the piston rod 17 is able to move freely and is displaced by a recall spring or due to the expansion intrinsic with the braking means, towards the left (Figure 1).

The pin 23 is able to travel relative to the piston rod 9 within the slot of the fork end 35, without any resistance being opposed to this movement.

When the cylinder chamber 3 or the pressure line connected with the pressure air connection has again been repaired, i.e. has once again been made fluid-tight, the cylinder chamber is subjected to pressure for displacing the piston towards the left. Before the stop ring 31 is applied at the inner side of the base 11 of the brake cylinder, the pin 23, which is maintained to be substantially stationary by the piston rod 17, passes into the zone of the short limb 25 of the Slot, i.e. the piston rod 9 travels towards the left in Figure 1, until the pin 23 snaps into the short limb 25 under the bias applied by the torsion spring 47, and bears at the end of the short limb (Figure 2).

Then, the non-positive connection between the piston rod and the piston tube is restored via the pin 23 and the bush 21. Consequently, the normal braking operation is able once again to take place.

The invention is not limited to the embodiment shown, i.e. instead of the torsion spring 47 it is possible to employ also a differently designed spring element in each particular instance biasing the spindle in a direction of rotation. Furthermore, the guiding of the piston rod 17 within the bush 21 is not limited to the construction shown of the head 19; in every case, it is necessary to provide an arrangement which ensures that the bush 21 through which the pin 23 extends is able to rotate relative to the piston rod 17 which is non-rotatably retained.

Furthermore,the guiding of the pin 23 relative to the spindle 37, as shown, is not restricted to the arrangement illustrated: according to an embodiment which is advantageous from the cost aspect, the fork end 35 is dispensed with, i.e. instead of the fork end there extends from the spindle a spike which extends through a transverse bore formed in the pin. Thus, the pin can, by means of the transverse bore, be displaced on the spike and performs thereby the same above-discussed relative movements with regard to the piston rod 9.

WHAT WE CLMM IS: 1. An actuator device adapted for coupling with an operating member of a brake system and operable in use under spring action to effect application of the brake system, and when supplied with pressure medium to effect release of the brake system, in which the actuator device comprises:: a cylinder; a piston slidably mounted in said cylinder and held against rotation relative to the cylinder; a pressure chamber defined in said cylinder on one side of said piston to receive a supply of pressure medium for urging the piston in a brake-release direction; spring means arranged in said cylinder and engaging said piston to urge the latter in a brake-application direction; a hollow piston rod connected to said piston so as also to be held against rotation relative to the cylinder; a connector sleeve housed within and connected to said piston rod, said sleeve being adapted for connection to an operating member of a brake system;; a connector pin extending transversely through said sleeve to interconnect the sleeve and the hollow piston rod, the connector pin being adjustable between a first connecting mode in which the pin is operable to transmit linear thrust between the piston rod and the sleeve and a second connecting mode in which the pin allows relative longitudinal movement to take place between the piston rod and the sleeve; an adjustment spindle in said hollow piston rod and connected to said connector pin, said spindle being pivotable about its longitudinal axis in order to pivot the connector pin between its first and second connecting modes; and means biasing the spindle so that the latter urges the connector pin to occupy its first connecting mode.

2. An actuator device according to Claim 1, in which each end of the connector pin is moveable along the limbs of a respective L shaped slot formed in the wall of the hollow piston rod, each Shaped slot having a first limb extending peripherally in a plane per pendicular to the axis of the hollow piston rod and a second limb extending perpendicular to the first limb and generally parallel to said axis, and in which the ends of the connector pin are received in the first limbs of the slots in the first connecting mode and are received in the second limbs of the slots in the second connecting mode.

3. An actuator device according to Claim 2, in which the spring means comprises a compression spring arranged in the cylinder on the other side of said piston and surrounding said hollow piston rod; the adjustment spindle has a fork at one end in which the connector pin is received and at the other end, located externally of the cylinder, a connector which is engageable by a tool or key in order to pivot the spindle; and the biasing means comprises a torsion spring which engages said spindle.

4. An actuator device according to Claim 3, in which the torsion spring surrounds the adjustment spindle within the pressure chamber of the cylinder, one end of the torsion spring being fixed to the spindle and the opposite end of the torsion spring being connected to an end face of the cylinder.

5. An actuator device according to Claim 3 or 4, in which the connector at the other end of the adjustment spindle comprises a hexagon rotatable by means of a key and fixed by means of a notched pin to said other end of the spindle.

6. An actuator device according to any one of the preceding Claims, in which the connector pin is guided by means of a guide sleeve and an O-ring, to extend radially through said sleeve.

7. An actuator device according to Claim 3 or any one of Claims 4 to 6 when appendant to Claim 3, in which the piston is held against rotation within the cylinder by means of a securing wedge carried by the piston and engaging positively in a facing groove formed in the adjacent end of the compression spring, the opposite end of the spring being connected to an adjacent end face of the cylinder by means of a further securing wedge carried thereby and engaging positively in a facing groove in said opposite end of the compression spring.

8. An actuator device according to Claim 1 or 2, in which the spring means comprises a compression spring arranged in the cylinder on the other side of said piston and surrounding said hollow piston rod; the adjustment spindle has a spike at one end on which the connector pin is longitudinally slideably mounted and at the other end, located externally of the cylinder, a connector which is engageable by a tool or key in order to pivot the spindle; and the biasing means comprises a torsion spring which engages said spindle.

9. An actuator device according to Claim 1 and substantially as hereinbefore described with reference to, and as shown in the accompanying drawing.

10. A brake system including an actuator device according to any one of the preceding

Claims

Claims.