Vacuum boost for vehicle braking

• US 9,573,576 B2
• Filed: 09/15/2014
• Issued: 02/21/2017
• Est. Priority Date: 11/08/2010
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Martin, Douglas Raymond, Crombez, Dale Scott, Fridman, Moses Alexander
• Primary Examiner(s): VILAKAZI, SIZO BINDA
• Application Number:
  US14/486,062
• Publication Number:
  US 20150000634A1
• Time in Patent Office: 890 Days
• Field of Search: 123/90.15, 123/90.16, 123/90.17, 123/347, 123/349, 180 6521- 6529, 303/114.3, 303/115.3, 701/110
• US Class Current: 1/1
• CPC Class Codes: B60T 13/662 characterised by specified functions of the control system components
• 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
• CPC Class Codes: B60T 17/221 Procedure or apparatus for checking or keeping in a correct functioning condition of brake systems hydraulic pressure systems in general F15B19/00, F15B21/04; testing structures or apparatus G01M
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/10 including control of change-speed gearings
• CPC Class Codes: B60W 10/188 hydraulic brakes
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 2510/0671 Engine manifold pressure
• CPC Class Codes: B60W 2510/182 Brake pressure, e.g. of fluid or between pad and disc
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: B60W 2710/0666 Engine torque
• CPC Class Codes: B60W 2710/0677 Engine power
• CPC Class Codes: B60W 2710/0683 Engine manifold pressure
• CPC Class Codes: B60W 2710/1005 Transmission ratio engaged
• CPC Class Codes: B60W 2710/182 Brake pressure, e.g. of fluid or between pad and disc
• CPC Class Codes: B60W 30/18109 Braking
• CPC Class Codes: B60Y 2200/92 Hybrid vehicles
• CPC Class Codes: B60Y 2300/18108 Braking
• CPC Class Codes: F02D 13/0238 : by shifting the phase, i.e. the opening periods of the valves are constant
• CPC Class Codes: F02D 2250/41 : Control to generate negative pressure in the intake manifold, e.g. for fuel vapor purging or brake booster
• CPC Class Codes: F02D 2700/07 : Automatic control systems according to one of the preceding groups in combination with control of the mechanism receiving the engine power
• CPC Class Codes: F02D 29/02 : peculiar to engines driving vehicles; peculiar to engines driving variable pitch propellers
• CPC Class Codes: F02D 31/001 : Electric control of rotation speed
• CPC Class Codes: F02D 41/0055 : Special engine operating conditions, e.g. for regeneration of exhaust gas treatment apparatus
• CPC Class Codes: F02D 41/021 : Introducing corrections for particular conditions exterior to the engine conjoint control of vehicle sub-units for propelling the vehicle B60W30/18
• CPC Class Codes: F02D 9/02 : concerning induction conduits throttle valves, or arrangements thereof in conduits F02D9/08
• CPC Class Codes: F02M 35/10229 : the intake system acting as a vacuum or overpressure source for auxiliary devices, e.g. brake systems; Vacuum chambers air storage chamber F02B21/00
• CPC Class Codes: F02N 11/084 : State of vehicle accessories, e.g. air condition or power steering
• CPC Class Codes: F02N 2200/0807 : Brake booster state
• CPC Class Codes: Y02T 10/12 : Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 : Engine management systems
• CPC Class Codes: Y10S 903/93 : Conjoint control of different elements

Abstract

Methods for controlling vacuum within a brake booster by modifying powertrain operation include determining an intake manifold vacuum in response to actuation of a brake pedal. Increasing the intake manifold vacuum if the brake booster vacuum is less than a desired brake booster vacuum. In some embodiments, the transmission is downshifted to increase engine speed and intake manifold vacuum. In other embodiments, engine torque is reduced to increase intake manifold vacuum and the torque of the electric machine is increased to maintain a constant output torque.

Claims

1. A method of operating a vehicle powertrain including an engine and an electric machine, comprising:

receiving a powertrain torque request;

in response to application of a brake pedal and an intake manifold vacuum being less than a required brake booster vacuum, reducing torque of the engine to increase the intake manifold vacuum; and

increasing torque of the electric machine by a magnitude equal to the reduction in engine torque to meet the powertrain torque request.

2. The method of claim 1 wherein the vehicle further includes a power split hybrid transmission and wherein the method further comprises the step of:

adjusting gear ratio of the transmission to increase engine speed to further increase the vacuum when reducing the torque of the engine does not increase the vacuum to the required brake booster vacuum.

3. The method of claim 1 wherein the vehicle further includes an exhaust gas recirculation (EGR) system and wherein the method further comprises the step of:

disabling the EGR to increase the vacuum in the intake manifold when the vacuum is less than the required brake booster vacuum.

4. The method of claim 1 further comprising the steps of:

stopping the engine to operate in pure electric mode; and

in response to application of a brake pedal, starting the engine to increase the vacuum in the intake manifold when the vacuum is less than the required brake booster vacuum.

5. The method of claim 4 wherein the engine is started using the electric machine.

6. The method of claim 1 wherein the engine includes variable cam timing and wherein the method further comprises the step of:

adjusting cam timing of the engine to increase the vacuum in the intake manifold when the vacuum is less than the required brake booster vacuum.

7. A method, of operating a powertrain of a vehicle including an engine and an electric machine, comprising:

receiving a powertrain torque request;

receiving a first signal indicating brake booster vacuum;

receiving a second signal indicating intake manifold vacuum;

in response to application of a brake pedal, reducing torque of the engine to

increase the intake manifold vacuum if the brake booster vacuum is less than a desired brake booster vacuum and if the intake manifold vacuum is less than the desired brake booster vacuum; and

increasing a torque of the electric machine to offset the reduced torque of the engine to meet the powertrain torque request.

8. The method of claim 7 wherein the vehicle further includes a power split hybrid transmission and wherein the method further comprises the step of:

adjusting gear ratio of the transmission to increase engine speed to further increase the vacuum when reducing the torque of the engine does not increase the vacuum to the desired brake booster vacuum.

9. The method of claim 7 wherein the vehicle further includes an exhaust gas recirculation (EGR) system and wherein the method further comprises the step of:

disabling the EGR to increase the vacuum in the intake manifold when the vacuum is less than the required brake booster vacuum.

10. The method of claim 7 further comprising the steps of:

stopping the engine to operate in pure electric mode; and

in response to application of a brake pedal, starting the engine to increase the vacuum in the intake manifold when the vacuum is less than the desired brake booster vacuum.

11. The method of claim 10 wherein the engine is started using the electric machine.

12. The method of claim 7 wherein the engine includes variable cam timing and wherein the method further comprises the step of:

adjusting cam timing of the engine to increase the vacuum in the intake manifold when the vacuum is less than the desired brake booster vacuum.

13. The method of claim 7 wherein the torque of the electric machine is increased by a magnitude that is based on a magnitude of the reduction in engine torque.

14. The method of claim 7 wherein the torque of the electric machine is increased by a magnitude that is equal to the reduction in engine torque.