Transducer device for electrically operated brakes

• US 3,882,442 A
• Filed: 05/20/1974
• Issued: 05/06/1975
• Est. Priority Date: 01/12/1973
• Status: Expired due to Term

• Current Assignee: Harold C. Hubbard
• Original Assignee: Harold C. Hubbard
• Inventors: Hubbard, Harold C.
• Primary Examiner(s): Albritton, C. L.
• Application Number:
  US05/471,187
• Time in Patent Office: 351 Days
• Field of Search: 338/2,4,114,41,36,42,47,99,101,107,100,108,5,223-225 200/83L 303/3,7,15,20 73/398AR
• US Class Current: 338/41
• CPC Class Codes: B60T 13/58 Combined or convertible systems
• CPC Class Codes: B60T 13/741 acting on an ultimate actuator
• CPC Class Codes: B60T 7/04 foot actuated
• CPC Class Codes: B60T 7/20 specially for trailers, e.g. in case of uncoupling of or overrunning by trailer inertia-actuated overrun brakes B60T13/08
• CPC Class Codes: H01C 10/103 by using means responding to magnetic or electric fields, e.g. by addition of magnetisable or piezoelectric particles to the resistive material, or by an electromagnetic actuator

Abstract

An electro-mechanical pressure responsive control system and apparatus for controlling the current supplied to the actuating coils of electric brakes of a towed vehicle. The control includes a transducer having a flexible bellows with a powdered magnetic material received therein which, when compressed by foreshortening of the bellows due to operation of the brake system of a towing vehicle, decreases in electrical resistance and thereby supplies greater current to the brakes of the towed vehicle, and vice versa. A magnetic field prevents the powdered material from becoming permanently compacted by repeated cycling of the bellows.

Claims

1. A pressure responsive variable electrical resistance control device comprising a flexible bellows having a chamber therein and capable of being contracted and expanded in a given direction in response to forces applied oppositely thereto in said direction, a pair of electrically conductive contacts associated with said bellows and having conductive surfaces exposed within said chamber and disposed in spaced relation from one another along said given direction, a powdered magnetic material received in said bellows chamber between and in engagement with both of said conductive surfaces of said electrically conductive contacts, and means providing a magnetic field having lines of magnetic force extending within said bellows chamber generally in said given direction, whereby contraction of said bellows in response to said applied forces compresses said powdered magnetic material received in said bellows and thereby decreases the electrical resistance between said conductive contacts in proportion to the value of the applied forces and vice versa, and the lines of magnetic force tend to loosen or break up any compacting or adhesion of said powdered material upon reexpansion of said bellows in response to diminution of said applied forces.

2. The control device of claim 1 wherein said electrically conductive contacts comprise a pair of generally opposed axially aligned end caps connected to opposed ends of said flexible bellows, said end caps being made of an electrically conductive paramagnetic material.

3. The control device of claim 1 wherein said bellows comprises a generally tubular enclosure defining a chamber therein receiving said powdered material therein and a plurality of washers of a paramagnetic material generally axially spaced from one another and each at least partially received in said chamber.

4. The control device of claim 3 including a plurality of rings of a flexible resilient electrical insulating material interleaved with said washers and individually bonded to opposed faces of adjacent washers with said washers extending generally radially outwardly beyond said rings of flexible resilient material.

5. The control device of claim 4 wherein said flexible resilient material of said rings is a silicone rubber.

6. The control device of claim 4 wherein said conductive contacts comprise a pair of axially spaced generally opposed end caps each bonded to one of said rings of resilient flexible material with all of said washers interposed between said end caps.

7. The control device of claim 3 wherein said tubular enclosure comprises a resilient flexible sleeve secured to the outer peripheries of said washers.

8. The control device of claim 1 wherein said means providing a magnetic field comprises a pair of permanent magnets spaced apart in said chamber and mounted with their polar axes extending in said given direction.

9. The control device of claim 8 wherein said permanent magnets comprise axially polarized circular discs mounted in generally axially opposed relation adjacent opposite ends of said bellows chamber.

10. The control device of claim 9 wherein said magnets comprise ceramic disc magnets mounted in coaxially opposed relation adjacent opposite ends of said flexible bellows.

11. The control device of claim 10 wherein said disc permanent magnets are mounted one on each of said end caps in generally axially opposed relation with the one pole of one of said magnets facing the opposite pole of the other of said magnets.