Parking brake arrangement

Abstract

A parking brake arrangement for a brake unitalso having a service brake actuatorhas in a housing (4) a clock spring (10) for exercising a rotary motion at will on a parking brake gear wheel (8) in drive connection with a device (5-7) for delivering brake force from the brake unit (1). The arrangement has two axially movable control sleeves (15, 16) in drive connection with the clock spring (10). The control sleeves form clutches (8, 15 and 12, 16, respectively) with the parking brake gear wheel (8) and the housing (4), respectively. There are means (13, 18-21) for controlling the axial movements of the two control sleeves and the engagement of the two clutches in such a way that either one of them is always in engagement.

Claims

1. A parking brake arrangement for a brake unit having a service brake actuator, said parking brake arrangement comprising: a housing; a spring means for exercising a rotary motion at will on a parking brake gear wheel in drive connection with a device for delivering brake force from the brake unit; two axially movable control sleeves in drive connection with the spring means and forming clutches with the parking brake gear wheel and the housing, respectively; and means for controlling the axial movements of the two control sleeves and the engagement of the two clutches in such a way that either one of them is always in engagement.

2. The parking brake arrangement according to claim 1, wherein a release rod, provided with two control rings for engagement with either one of the control sleeves, is axially movable in the two control sleeves under the action in a parking brake release direction of a fixed electromagnet and in the opposite direction by a return spring.

3. The parking brake arrangement according to claim 2, wherein the release rod is provided with a magnetic anchor disc to be attracted by the electromagnet when energized.

4. The parking brake arrangement according to claim 2, wherein the release rod is provided with a release ring at an end extending out of the housing.

5. The parking brake arrangement according to claim 2, wherein the parking brake arrangement is configured to, by positioning the release rod in either of its axial end positions, engage one of the clutches and open the other clutch, and to engage both clutches when the release rod is in a position between its respective end positions.

6. The parking brake arrangement according to claim 1, wherein said clutches comprise tooth clutches.

7. The parking brake arrangement according to claim 1, wherein the two control sleeves are biased apart by a spring.

8. The parking brake arrangement according to claim 1, wherein the inner end of the spring means is attached to a spring sleeve, in which the control sleeves are axially movable.

9. The parking brake arrangement according to claim 1, wherein the spring means comprises a clock spring.

10. A method for applying and releasing a parking brake arrangement for a brake unit having a service brake actuator, said parking brake arrangement comprising: a housing; a spring means for exercising a rotary motion at will on a parking brake gear wheel in drive connection with a device for delivering brake force from the brake unit; two axially movable control sleeves in drive connection with the spring means and forming clutches with the parking brake gear wheel and the housing, respectively; and means for controlling the axial movements of the two control sleeves and the engagement of the two clutches in such a way that either one of them is always in engagement; the method comprising: applying the parking brake arrangement by axially positioning the control sleeves by said means for controlling the axial movements of the two control sleeves such that the clutch with the parking brake gear wheel is engaged and the clutch with the housing is open, thus allowing energy stored in said spring means to apply the parking brake; and releasing the parking brake by the service brake actuator providing a parking brake releasing rotation of said gear wheel which simultaneously winds up said spring means such that energy is stored in said spring means for subsequent brake force application, and then axially positioning said control sleeves such that the clutch with the parking brake gear wheel is open and the clutch with the housing is engaged.

11. The method according to claim 10, further comprising, during axial movement of the means for controlling the axial movements of the two control sleeves, engaging both clutches by a spring before either of the clutches is opened, regardless of which direction the axial movement of the means for controlling the axial movements of the two control sleeves has.

12. The method according to claim 10, wherein said means for controlling the axial movements of the two control sleeves is axially movable under the action in a parking brake release direction of a fixed electromagnet and in the opposite direction by a return spring.

13. A vehicle comprising a parking brake arrangement for a service brake actuator, said parking brake arrangement comprising: a housing; a spring means for exercising a rotary motion at will on a parking brake gear wheel in drive connection with a device for delivering brake force from the brake unit; two axially movable control sleeves in drive connection with the spring means and forming clutches with the parking brake gear wheel and the housing, respectively; and means for controlling the axial movements of the two control sleeves and the engagement of the two clutches in such a way that either one of them is always in engagement.

14. A vehicle according to claim 13, wherein the vehicle comprises a rail vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The teachings herein will be described in further detail below with reference to the accompanying drawings, in which

(2) FIG. 1 is an isometric view of a disc brake unit containing a parking brake arrangement,

(3) FIG. 2 is a side view of this disc brake unit with the parking brake arrangement shown in section, and

(4) FIG. 3 is an enlargement of the sectioned portion of FIG. 2.

DETAILED DESCRIPTION

(5) FIG. 1 shows a disc brake unit 1 for a rail vehicle (not shown). The unit 1 is to be mounted to the undercarriage of the vehicle in the vicinity of a brake disc on a wheel axle or the like on the vehicle. The teachings herein will be described in its use on a rail vehicle, but use on a road vehicle is not excluded.

(6) The brake unit 1 is to be mounted astraddle of a brake disc D (shown in dotted lines in FIG. 1), so that two brake pads 2, 3 may be brought into braking engagement with the brake disc D by a brake force generated within the brake unit 1. In the present case this brake force may either be a service brake force or a parking brake force.

(7) The means for transferring the brake force generated in the brake unit to a clamping force from the two brake pads 2, 3 are known in the art and will not be further described, except to the extent necessary for an understanding of the concept set forth herein.

(8) The disc brake unit 1having a housing 4 comprised of several partscontains in its lower portion in FIG. 2 (that is not shown in section) a service brake actuator, which is per se known and as its brake force generating element has an electric rotary motor provided with a reduction gearing. The brake force from the electric motor of the service brake actuator is delivered via a drive gear wheel 5 rotationally journalled in the housing 4.

(9) Further reference is now made to FIG. 3.

(10) The drive gear wheel 5 is connected to a drive sleeve 6 which is also rotationally journalled in the housing 4. The drive sleeve 6 formstogether with a non-rotational drive spindle 7, coaxially arranged within the drive sleeve, and appropriate ball meansa so-called ball screw. The spindle 7 extends through the open center of the drive gear wheel 5 and is ended by a push rod 7, which is connected to known means for transferring a linear movement to the left of the spindle 7 and thus the push rod T to a brake force applying movement of the brake pads 2, 3.

(11) The teachings herein are concerned with a parking brake arrangement, shown in the sectioned portion of FIG. 3.

(12) A parking brake gear wheel 8 is in gear engagement with the drive gear wheel 5. It is provided with a gear wheel sleeve 8 journalled in the housing 4 by means of a radial bearing 9.

(13) The power source for selectively driving the parking brake gear wheel 8 for parking braking is a powerful spring means 10 having its outer end in permanent engagement with the housing 4 and its inner end in permanent engagement with a spring sleeve 11. This spring sleeve 11 is rotationally journaled on the gear wheel sleeve 8 as well as on a support sleeve 12 attached in the housing 4. The spring means 10 is adapted to be tensioned to provide a rotational torque to the spring sleeve 11, indirectly driving the parking brake gear wheel 8. A preferred example of a spring means suited for such a task is a clock spring 10.

(14) Centrally located in the spring means 10 is an axially movable release rod 13, guided by the gear wheel sleeve 8 and a rod cup 14 in the support sleeve 12.

(15) Two control sleeves 15, 16 are rotationally arranged on the release rod 13 between the gear wheel sleeve 8 and the support sleeve 12. These two control sleeves 15, 16 are axially movable in relation to the spring sleeve 11 but are in drive engagement therewith. Each of them forms a tooth clutch with the gear wheel sleeve 8 and the support sleeve 12, respectively, these clutches being called a left clutch 8-15 and a right clutch 12-16, respectively. The two control sleeves 15, 16 together are axially shorter than the distance between the gear wheel sleeve 8 and the support sleeve 12 and are biased apart by means of an axial compression spring 17 in a suitably shaped space therein.

(16) The release rod 13 is provided with a magnetic anchor disc 13 in the rod cup 14 in the vicinity of a ring-shaped electromagnet 18 in the housing 4 around the release rod 13. Furthermore, the release rod 13 is provided with two control rings 19 and 20 to the left and to the right, respectively, of the two control sleeves 15, 16. A return spring 21 of compression-type is arranged between the rod cup 14 and the right control ring 20 for biasing the release rod 13 to the left in the drawing.

(17) The release rod 13 with its anchor disc 13 and its two control rings 19, 20, the return spring 21 and the electromagnet 18 can collectively be called means for controlling the axial movements of the two control sleeves.

(18) The arrangement is shown in FIG. 3 with the spring means 10 tensioned for later parking brake action and with the electromagnet 18 energized, so that the anchor disc 13 and thus the release rod 13 is held to the right in the drawing against the bias of the return spring 21. The left clutch 8-15 is disengaged, so that the parking brake gear wheel 8 is free to rotate, allowing normal service brake operation of the not disclosed service brake. The right clutch 12-16 is engaged, so that rotation of the spring sleeve 11 under the action of the spring means 10 is prevented.

(19) The following description starts from this shown position.

(20) If there is a voltage drop to the electromagnet 18, indicating that a parking brake application is desired or that an emergency braking is needed (because the electric service brake becomes non-operational), the release rod 13 will move to the left in the drawing under the bias from the return spring 21. Due to the geometry, both the right clutch 12-16 and the left clutch 8-15 are in engagement for a short while, before the right clutch 12-16 becomes unengaged. Now the force from the spring means 10 can be transmitted via the left clutch 8-15 and the gear wheel sleeve 8 to the gear wheel 8 and further on to the ball screw 6, 7. Parking or emergency braking is performed under the action of the spring means 10.

(21) Due to the working sequence of the two clutches 8-15 and 12-16 and the lack of slip therein, no energy from the spring means 10 is lost.

(22) After a parking or emergency brake application, the spring means 10 can be tensioned again by the service brake actuator via the gear wheel 8, the gear wheel sleeve 8, the left clutch 8-15, the control sleeves 15, 16 and the spring sleeve 11; provided that the electromagnet 18 remains non-energized until the spring means 10 is tensioned to the desired extent.

(23) The release rod 13 is provided with a release ring 13 at its end extending out of the housing 4 for enabling a manual release of the parking brake arrangement at will.