Self contained, supplemental vacuum assist unit for vehicle brake booster

• US 6,324,845 B1
• Filed: 06/23/2000
• Issued: 12/04/2001
• Est. Priority Date: 06/23/2000
• Status: Expired due to Term

• Current Assignee: BWI Company Limited SA (Shougang Corporation)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Mohile, Vivek V., Poole, Douglas E., Haerr, Timothy Allen, Schlangen, Timothy M., Zehnder, James William II, Fulks, Gary Chris
• Primary Examiner(s): Look, Edward K.
• Assistant Examiner(s): Kershteyn, Igor
• Application Number:
  US09/602,783
• Time in Patent Office: 529 Days
• Field of Search: 603/97, 604/05, 603/26, 605/82, 91/1
• US Class Current: 60/582
• CPC Class Codes: B60T 13/52 indirect, i.e. vacuum booster units
• CPC Class Codes: B60T 13/72 in vacuum systems or vacuum booster units
• CPC Class Codes: B60T 17/02 Arrangements of pumps or compressors, or control devices therefor

Abstract

A self contained, supplemental vacuum assist unit is provided for use with a vacuum brake booster and a source of vacuum in a motor vehicle. The unit includes, within a single housing, an electric motor, an air pump driven by the motor, a manifold defining air exhaust and assist vacuum chambers, a pair of check valves permitting air flow from the pump outlet and the assist vacuum chamber to the air exhaust chamber, an outlet from the air exhaust chamber with a fitting for connection to the vacuum source, an opening from the assist vacuum chamber with a fitting providing communication directly to the interior of the vacuum chamber of the booster, and a pressure sensor including a diaphragm, plunger, magnet with a Hall effect sensor and motor control circuitry on a circuit board within the assist vacuum chamber. The unit is compact, light weight and efficient and is designed for attachment directly to the booster with no intervening vacuum hose therebetween.

Claims

1. A self contained, supplemental vacuum assist unit for use with a vacuum brake booster and a source of vacuum in a motor vehicle, the vacuum brake booster having a vacuum chamber and a working pressure chamber, the unit comprising, in combination:

a housing defining an assist vacuum chamber having an opening with a fitting adapted for connection to the vacuum chamber of the vacuum brake booster and further defining an air exhaust chamber having an opening with a fitting adapted for connection to the source of vacuum, the assist vacuum chamber and the air exhaust chamber being separated by a wall;

a first opening in the wall having a first unidirectional flow valve permitting air flow only from the assist vacuum chamber to the air exhaust chamber;

an electric motor driven air pump in the housing having an inlet from the assist vacuum chamber and an outlet to the air exhaust chamber, the pump having associated therewith a second unidirectional flow valve permitting air flow through the air pump only from the assist vacuum chamber to the air exhaust chamber;

an electric circuit board within the assist vacuum chamber having a Hall effect sensor thereon so as to sense a magnetic field of a magnet adjacent the sensor and a control circuit thereon responsive to the Hall effect sensor to control operation of the electric motor driven air pump;

the housing further defining an opening from the assist vacuum chamber to a source of air at atmospheric pressure, the opening being closed by a flexible diaphragm;

a plunger activated by the diaphragm for axial movement therewith due to changes in pressure across the diaphragm; and

a permanent magnet affixed to the plunger adjacent the Hall effect sensor, the permanent magnet generating a magnetic field sensed by the Hall effect sensor and the Hall effect sensor being responsive thereto to generate a signal changing with the position of the permanent magnet and thus with the pressure across the diaphragm.

2. The self contained, supplemental vacuum assist unit of claim 1 in which the electric circuit board is adapted to guide the motion of the plunger in a predetermined direction relative to the Hall effect sensor.

3. The self contained, supplemental vacuum assist unit of claim 1 in which the permanent magnet is affixed on an end of the plunger in an axially adjustable manner.

4. The self contained, supplemental vacuum assist unit of claim 1 in which the permanent magnet is affixed on an end of the plunger in an axial position relative thereto to cross a temperature invariant axis of the Hall effect sensor at a predetermined pressure across the diaphragm corresponding to a minimum desired vacuum level in the vacuum chamber of the vacuum brake booster.

5. The self contained, supplemental vacuum assist unit of claim 3 in which the diaphragm and plunger are biased by a spring reacting against a spring seat member adjustable to vary the spring preload.

6. The self contained, supplemental vacuum assist unit of claim 1 in which one or more brackets are provided for mounting the unit directly on the vacuum booster and the fitting is adapted to directly communicate the assist vacuum chamber to the vacuum chamber of the booster, without the use of intervening, removable conduits between the unit and the booster, when the unit is so mounted.

7. The self contained, supplemental vacuum assist unit of claim 6 further having two levels of sound isolation apparatus between the electric motor in the unit and the booster:

first sound isolating mounting devices associated with the brackets, and second sound isolating mounting devices between the electric motor and the housing of the unit.

8. The self contained, supplemental vacuum assist unit of claim 1 in which the second unidirectional valve is disposed downstream of the outlet of the air pump.

9. The self contained, supplemental vacuum assist unit of claim 1 in which the housing comprises a manifold housing with an end cap, the manifold housing having at least one interior wall dividing the manifold housing into the vacuum assist chamber and the air exhaust chamber, and the end cap completing the assist vacuum chamber, holding the diaphragm, plunger and magnet of the sensor, and supporting the circuit board and external electrical connection apparatus therefrom.

10. The self contained, supplemental vacuum assist unit of claim 9 in which the housing further comprises a motor/pump housing attached to the manifold housing and having an opening to the assist vacuum chamber through which electrical connection is provided therefrom to the motor, whereby the magnet, circuit board, Hall effect sensor and motor are all maintained within the vacuum supplied to the booster, regardless of the source of such vacuum.

11. Vehicle power brake assist apparatus for use with a source of vacuum in a motor vehicle, the apparatus comprising a vacuum brake booster and a supplemental vacuum assist unit, the vacuum brake booster having a vacuum chamber and a working pressure chamber, the supplemental vacuum assist unit being affixed to the vacuum brake booster by one or more brackets and comprising, in combination:

a housing defining an assist vacuum chamber having an opening with a fitting directly communicating with the vacuum chamber of the vacuum brake booster and further defining an air exhaust chamber having an opening with a fitting adapted for connection to the source of vacuum, the assist vacuum chamber and the air exhaust chamber being separated by a wall;

a first opening in the wall having a first unidirectional flow valve permitting air flow only from the assist vacuum chamber to the air exhaust chamber;

an electric motor driven air pump in the housing having an inlet from the assist vacuum chamber and an outlet to the air exhaust chamber, the pump having associated therewith a second unidirectional flow valve permitting air flow through the air pump only from the assist vacuum chamber to the air exhaust chamber;

an electric circuit board within the assist vacuum chamber having a Hall effect sensor thereon so as to sense a magnetic field of a magnet adjacent the sensor and a control circuit thereon responsive to the Hall effect sensor to control operation of the electric motor driven air pump;

the housing further defining an opening from the assist vacuum chamber to a source of air at atmospheric pressure, the opening being closed by a flexible diaphragm;

a plunger activated by the diaphragm for axial movement therewith due to changes in pressure across the diaphragm;

a permanent magnet affixed to the plunger adjacent the Hall effect sensor, the permanent magnet generating a magnetic field sensed by the Hall effect sensor and the Hall effect sensor being responsive thereto to generate a signal changing with the position of the permanent magnet and thus with the pressure across the diaphragm.

12. The vehicle power brake assist apparatus of claim 11 in which the electric circuit board is adapted to guide the motion of the plunger in a predetermined direction relative to the Hall effect sensor.

13. The vehicle power brake assist apparatus of claim 11 in which the permanent magnet is affixed on an end of the plunger in an axially adjustable manner.

14. The vehicle power brake assist apparatus of claim 11 in which the permanent magnet is affixed on an end of the plunger in an axial position relative thereto to cross a temperature invariant axis of the Hall effect sensor at a predetermined pressure across the diaphragm corresponding to a minimum desired vacuum level in the vacuum chamber of the vacuum brake booster.

15. The vehicle power brake assist apparatus of claim 13 in which the diaphragm and plunger are biased by a spring reacting against a spring seat member adjustable to vary the spring preload.

16. The vehicle power brake assist apparatus of claim 11 in which the second unidirectional valve is disposed downstream of the outlet of the air pump.

17. The vehicle power brake assist apparatus of claim 11 in which the housing comprises a manifold housing with an end cap, the manifold housing having at least one interior wall dividing the manifold housing into the vacuum assist chamber and the air exhaust chamber, and the end cap completing the assist vacuum chamber, holding the diaphragm, plunger and magnet of the sensor, and supporting the circuit board and external electrical connection apparatus therefrom.

18. The vehicle power brake assist apparatus of claim 17 in which the housing further comprises a motor/pump housing attached to the manifold housing and having an opening to the assist vacuum chamber through which electrical connection is provided therefrom to the motor, whereby the magnet, circuit board, Hall effect sensor and motor are all maintained within the vacuum supplied to the booster, regardless of the source of such vacuum.

19. The vehicle power brake assist apparatus of claim 11 further having two levels of sound isolation apparatus between the electric motor in the unit and the booster:

first sound isolating mounting devices associated with the brackets, and second sound isolating mounting devices between the electric motor and housing of the unit.