Vehicle braking system with proportional poppet valve pressure control strategy

In an EHB system where pressure in a brake is controlled by the combined action of a First valve and a second valve, a method of controlling the voltage applied to the first valve and the second valve comprising:

• a) controlling the first valve using a bulk flow mode when |Qdem|>|sigma*Kh|, and holding the second valve firmly closed;
• and
• b) controlling the second valve using a leakage control mode when |switch|<|Qdem|<|sigma*Kh|, and holding the first valve firmly closed;
• wherein Qdem is a demanded flow, sigma is a leakage gain factor, Kh is a hydraulic gain factor, and switch is a threshold demanded flow constant at and below which a constant voltage is applied to each of the valves.

In an EHB system where pressure in a brake is controlled by the combined action of a first valve and a second valve, a method of controlling the voltage applied to the first valve and the second valve comprising:

• a) controlling the first valve using a leakage control mode when |switch|<|Qdem|<|sigma*Kh|, and holding the second valve firmly closed;
• and
• b) controlling the first valve and the second valve using a pressure control mode when |Qdem|<|switch|, holding both said valves firmly closed;
• wherein Qdem is a demanded flow, sigma is a leakage gain factor, Kh is a hydraulic gain factor, and switch is a threshold demanded flow constant at and below which a constant voltage is applied to each of the valves.

In an EHB system where pressure in a brake is controlled by the combined action of a first valve and a second valve, a method of controlling the voltage applied to the first valve and the second valve comprising:

• a) controlling the first valve using a leakage control mode when switch<Qdem<sigma*Kh, and holding the second valve firmly closed;
• and
• b) controlling the second valve using a leakage control mode when −switch>Qdem>−sigma*Kh, and holding the first valve firmly closed;
• wherein Qdem is a demanded flow, sigma is a leakage gain factor, Kh is a hydraulic rain factor, and switch is a threshold demanded flow constant at and below which a constant voltage is applied to each of the valves.

In an EHB system where pressure in a brake is controlled by the combined action of a first valve and a second valve, a method of controlling the voltage applied to th(e first valve and the second valve comprising:

• a) controlling the first valve using a leakage control mode when |switch|<|Qdem|<|sigma*Kh|, and holding the second valve firmly closed;
• and
• b) controlling the second valve using a bulk flow mode when |Qdem|>|sigma*Kh|, and holding the first valve firmly closed;
• wherein Qdem is a demanded flows sigma is a leakage gain factor, Kh is a hydraulic gain factor, and switch is at threshold demanded flow constant at and below which a constant voltage is applied to each of the valves.

In an EHB system where pressure in a brake is controlled by the combined action of a first valve and a second valve, a method of controlling the voltage applied to the first valve and the second valve comprising:

• a) controlling the first valve using a bulk flow mode when |Qdem|>|sigma*Kh|, and holding the second valve firmly closed;
• and
• b) controlling the first valve using a leakage control mode when |switch|<|Qdem|<|sigma*Kh|, and holding the second valve firmly closed;
• and
• c) controlling the first valve and the second valve using a pressure control mode when |Qdem|<|switch|, holding both said valves firmly closed;
• wherein Qdem is a demanded flow, sigma is a leakage gain factor, Kh is a hydraulic gain factor, and switch is a threshold demanded flow constant at and below which a constant voltage is applied to each of the valves.

In an EHB system where pressure in a brake is controlled by the combined action of a first valve and a second valve, a method of controlling the voltage applied to the first valve and the second valve comprising:

• a) controlling the first valve using a bulk flow mode when |Qdem|>|sigma*Kh|, and holding the second valve firmly closed;
• and
• b) controlling the first valve using a leakage control mode when |switch|<|Qdem|<|sigma*Kh|, and holding the second valve firmly closed;
• and
• c) controlling the second valve using a leakage control mode when but |switch|<|Qdem|<|sigma*Kh|, and holding the first valve firmly closed;
• wherein Qdem is a demanded flow, sigma is a leakage gain factor, Kh is a hydraulic gain factor, and switch is a threshold demanded flow constant at and below which a constant voltage is applied to each of the valves.

In an EHB system where pressure in a brake is controlled by the combined action of a first valve and a second valve, a method of controlling the voltage applied to the first valve and the second valve comprising:

• a) controlling the first valve using a bulk flow mode when |Qdem|>|sigma*Kh|, and holding the second valve firmly closed;
• and
• b) controlling the first valve using a leakage control mode when |switch|<|Qdem|<|sigma*Kh|, and holding the second valve firmly closed;
• and
• c) controlling the second valve using a bulk flow mode when |Qdem|>|sigma*Kh|, and holding the first valve firmly closed,
• wherein Qdem is a demanded flow, sigma is a leakage gain factor, Kh is a hydraulic gain factor, and switch is a threshold demanded flow constant at and below which a constant voltage is applied to each of the valves.

In an EHB system where pressure in a brake is controlled by the combined action of a first valve and a second valve, a method of controlling the voltage applied to the first valve and the second valve comprising:

• a) controlling the first valve using a leakage control mode when |switch|<|Qdem|<|sigma*Kh|, and holding the second valve firmly closed;
• and
• b) controlling the first valve and the second valve using a pressure control mode when |Qdem|<|switch|, holding both said valves firmly closed;
• and
• c) controlling the second valve using a bulk flow mode when |Qdem|>|sigma*Kh|, and holding the first valve firmly closed;
• wherein Qdem is a demanded flow, sigma is a leakage gain factor, Kh is a hydraulic gain factor, and switch is a threshold demanded flow constant at and below which a constant voltage is applied to each of the valves.

In an EHB system where pressure in a brake is controlled by the combined action of a first valve and a second valve, a method of controlling the voltage applied to the first valve and the second valve comprising:

• a) controlling the first valve using a leakage control mode when |switch|<|Qdem|<|sigma*Kh|, and holding the second valve firmly closed;
• and
• b) controlling the first valve and the second valve using a pressure control mode when |Qdem|<|switch|, holding both said valves firmly closed;
• and
• c) controlling the second valve using a bulk flow mode when |switch|<|Qdem|<|sigma*Kh|, and holding the first valve firmly closed;
• wherein Qdem is a demanded flow, sigma is a leakage gain factor, Kh is a hydraulic gain factor, and switch is a threshold demanded flow constant at and below which a constant voltage is applied to each of the valves.

In an EHB system where pressure in a brake is controlled by the combined action of a first valve and a second valve, a method of controlling the voltage applied to the first valve and the second valve comprising:

• a) controlling the first valve using a leakage control mode when |Qdem|<|sigma*Kh|, and holding the second valve firmly closed;
• and
• b) controlling the first valve using a leakage control mode when |switch|<|Qdem|<|sigma*Kh|, and holding the second valves firmly closed;
• and
• c) controlling the first valve and the second valve using a pressure control mode when |Qdem|<|switch|, holding both said valves firmly closed;
• and
• d) controlling the second valve using a leakage control mode when |switch|<|Qdem|<|sigma*Kh|, and holding the first valve firmly closed;
• wherein Qdem is a demanded flow, sigma is a leakage gain factor, Kh is a hydraulic gain factor, and switch is a threshold demanded flow constant at and below which a constant voltage is applied to each of the valves.

In an EHB system where pressure in a brake is controlled by the combined action of a first valve and a second valve, a method of controlling the voltage applied to the first valve and the second valve comprising:

• a) controlling the first valve using a leakage control mode when |Qdem|<|sigma*Kh|, and holding the second valve firmly closed;
• and
• b) controlling the first valve using a leakage control mode when |switch|<|Qdem|<|sigma*Kh|, and holding the second valve firmly closed;
• and
• c) controlling the first valve and the second valve using a pressure control mode when |Qdem|<|switch|, holding both said valves firmly closed;
• and
• d) controlling the second valve using a bulk flow mode when |Qdem|<|sigma*Kh|, and holding the first valve firmly closed;
• wherein Qdem is a demanded flow, sigma is a leakage gain factor, Kh is a hydraulic gain factor, and switch is a threshold demanded flow constant at and below which a constant voltage is applied to each of the valves.

In an EHB system where pressure in a brake is controlled by the combined action of a first valve and a second valve, a method of controlling the voltage applied to the first valve and the second valve comprising:

• a) controlling the first valve using a bulk flow control method when |Qdem|>|sigma*Kh|, and holding the second valve firmly closed;
• and
• b) controlling the first valve using a leakage control mode when |switch|<|Qdem|<|sigma*Kh|, and holding the second valve firmly closed;
• and
• c) controlling the second valve using a leakage control mode when |switch|<|Qdem|<|sigma*Kh|, and holding the first valve firmly closed;
• and
• d) controlling the second valve using a bulk flow mode when |Qdem|>|sigma*Kh|, and holding the first valve firmly closed;
• wherein Qdem is a demanded flow, sigma is a leakage gain factor, Kh is a hydraulic gain factor, and switch is a threshold demanded flow constant at and below which a constant voltage is applied to each of the valves.

In an EHB system where pressure in a brake is controlled by the combined action of a first valve and a second valve, a method of controlling the voltage applied to the first valve and the second valve comprising:

• a) controlling the first valve using a bulk flow mode when |Qdem|>|sigma*Kh|, and holding the second valve firmly closed;
• and
• b) controlling the first valve using a leakage control mode when |switch|<|Qdem|<|sigma*Kh|, and holding the second valve firmly closed;
• and
• c) controlling the first valve and the second valve using a pressure control mode when |Qdem|<|switch|, holding both said valves firmly closed;
• and
• d) controlling the second valve using a leakage control mode when |switch|<|Qdem|<|sigma*Kh|, and holding the first valve firmly closed;
• and
• e) controlling the second valve using a bulk flow control mode when |Qdem|>|sigma*Kh|, and holding the first valve firmly closed;
• wherein Qdem is a demanded flow, sigma is a leakage gain factor, Kh is a hydraulic gain factor, and switch is a threshold demanded flow constant at and below which a constant voltage is applied to each of the valves.

A method of controlling the voltage applied to an apply and dump valve in an EHB system where pressure in a brake is controlled by the combined action of the apply and dump valve comprising:

• a) providing an apply and dump valve in a hydraulic circuit, each proportionally controlled by a solenoid;
• b) applying a brake pedal in the EHB system establishing a flow demand within the EHB hydraulic system;
• c) inputting the demanded flow into a control algorithm;
• d) computing the voltage required to achieve the demanded flow;
• e) applying a voltage across the solenoid to actuate the apply valve to use bulk flow with a flow demand greater than sigma*Kh;
• f) applying a voltage across the solenoid to actuate the apply valve to use leakage flow with a flow demand greater than switch and less than sigma*Kh;
• g) applying a voltage to the dump valve to eliminate its leakage when there is a demanded flow greater than negative switch;
• h) applying a voltage to the apply valve to eliminate its leakage when there is a demanded flow less than switch;
• i) applying a voltage across the solenoid to actuate the dump valve to use bulk flow with a flow demand less than negative sigma*Kh;
• and
• j) applying a voltage across the solenoid to actuate the dump valve to use leakage flow with a flow demand less than negative switch, but greater than negative sigma*Kh;
• wherein sigma is a leakage gain factor, and Kh is a hydraulic gain factor.

A method of controlling the voltage applied to an apply and dump valve in an EHB system where pressure in a brake is controlled by the combined action of the apply and dump valve where voltage is supplied relative to demanded pressure wherein the method comprises the steps of:

• a) controlling voltage applied to an apply valve along a positively sloped first curve of voltage versus demanded flow in a positive flow demand, bulk flow region;
• b) controlling voltage applied to an apply valve along a positively sloped second curve of voltage versus demanded flow in a positive flow demand, leakage flow region;
• c) controlling voltage applied to an apply valve and dump valve along an unsloped curve of voltage versus demanded flow in a region where flow demand is between a negative switch value and a positive switch value;
• d) controlling voltage;
• applied to a dump valve along a negatively sloped fourth curve of voltage versus demanded flow in a negative flow demand, leakage flow region;
• and
• e) controlling voltage applied to a dump valve along a negatively sloped fifth curve of voltage versus demanded flow in a negative flow demand, bulk flow region.