Electric parking brake

An electric parking-brake system for a utility vehicle with a parking-brake device, which includes a spring-type actuator, and with a trailer parking-brake port, comprising:

• a first electric parking brake, wherein the first electric parking brake has been formed between a compressed-air supply and a first discharge line which couples to the parking-brake device;
• and
• a second electric parking brake, wherein the second electric parking brake has been formed between the compressed-air supply and a second discharge line which couples to the trailer parking-brake port;
• wherein each of the electric parking brakes includes:
• a feed line for brake-pressure air;
• a discharge line for brake-pressure air for a pneumatic brake device;
• a first valve and a second valve which are each switchable between a stable state and an activated state in response to electrical control signals;
• and
• a valve device, which is connected between each feed line and each discharge line and exhibits a control input, each valve device being switchable control input, the feed line being connected to each discharge line in the activated state;
• wherein each first valve in the stable state or in the activated state connects the control input of each valve device to each discharge line, to retain a current state of each valve device when the brake-pressure air is applied to the discharge line, and in the activated state or in the stable state connects the control input to each second valve,
• wherein each valve device includes a booster valve with at least one spring-biased piston and with a vent opening, and wherein each valve device is configured to vent each discharge line in the stable state, and each vent opening points in a direction of motion of each piston or is arranged to the side thereof, and
• wherein each valve device includes a first inlet, which is connected to each feed line, a second inlet and a third inlet which is connected to each discharge line, wherein each second inlet is the control input for switching between each stable state and each activated state, in response to the control signals.

A utility vehicle with a braking device which exhibits at least one spring-loaded cylinder which in the unpressurized state activates a parking brake via a biasing force, comprising:

• an electric parking-brake system, the parking brake being releasable by brake pressure-air and a discharge line;
• wherein the electric parking-brake system includes:
• a first electric parking brake, wherein the first electric parking brake has been formed between a compressed-air supply and a first discharge line which couples to the parking-brake device;
• and
• a second electric parking brake, wherein the second electric parking brake has been formed between the compressed-air supply and a second discharge line which couples to a trailer parking-brake port;
• wherein each of the electric parking brakes includes:
• a feed line for brake-pressure air;
• a discharge line for brake-pressure air for a pneumatic brake device;
• a first valve and a second valve which are each switchable between a stable state and an activated state in response to electrical control signals;
• and
• a valve device, which is connected between each feed line and each discharge line and exhibits a control input, each valve device being switchable between a stable state and an activated state in response to control signals at the control input, each feed line being connected to each discharge line in the activated state;
• wherein each first valve in the stable state or in the activated state connects the control input of each valve device to each discharge line, to retain a current state of each valve device when the brake-pressure air is applied to each discharge line, and in the activated state or in the stable state connects the control input to each second valve,
• wherein each valve device includes a booster valve with at least one spring-biased piston and with a vent opening, and wherein each valve device is configured to vent each discharge line in the stable state, and each vent opening points in a direction of motion of each piston or is arranged to the side thereof, and
• wherein each valve device includes a first inlet, which is connected to each feed line, a second inlet and a third inlet which is connected to each discharge line, wherein each second inlet is the control input for switching between each stable state and each activated state in response to the control signals.

A method for actuating an electric parking brake, the method comprising:

• activating, upon establishing a desire to drive off, a valve device by activating a first valve;
• and
• switching, upon establishing a desire to park, the valve device into a stable state by venting a control input by activating at least the first valve;
• wherein the electric parking brake includes:
• a feed line for brake-pressure air;
• a discharge line for brake-pressure air for a pneumatic brake device;
• the first valve and a second valve which are each switchable between a stable state and an activated state in response to electrical control signals;
• and
• the valve device, which is connected between the feed line and the discharge line and exhibits the control input, the valve device being switchable between the stable state and an activated state in response to control signals at the control input, the feed line being connected to the discharge line in the activated state;
• and
• wherein the first valve in the stable state or in the activated state connects the control input of the valve device to the discharge line, to retain a current state of the valve device when the brake-pressure air is applied to the discharge line, and in the activated state or in the stable state connects the control input to the second valve,
• wherein the valve device includes a booster valve with at least one spring-biased piston and with a vent opening, and wherein the valve device is configured to vent the discharge line in the stable state, and the vent opening points in a direction of motion of the piston or is arranged to the side thereof, and
• wherein the valve device includes a first inlet, which is connected to the feed line, a second inlet and a third inlet which is connected to the discharge line, wherein the second inlet is the control input for switching between the stable state and the activated state in response to the control signals.

A non-transitory computer readable medium having a computer-program, which is executable by a processor, comprising:

• a program code arrangement having program code for actuating an electric parking brake, by performing the following:
• activating, upon establishing a desire to drive off, a valve device by activating a first valve;
• and
• switching, upon establishing a desire to park, the valve device into a stable state by venting a control input by activating at least the first valve;
• wherein the electric parking brake includes:
• a feed line for brake-pressure air;
• a discharge line for brake-pressure air for a pneumatic brake device;
• the first valve and a second valve which are each switchable between a stable state and an activated state in response to electrical control signals;
• and
• the valve device, which is connected between the feed line and the discharge line and exhibits the control input, the valve device being switchable between the stable state and an activated state in response to control signals at the control input, the feed line being connected to the discharge line in the activated state;
• and
• wherein the first valve in the stable state or in the activated state connects the control input of the valve device to the discharge line, to retain a current state of the valve device when the brake-pressure air is applied to the discharge line, and in the activated state or in the stable state connects the control input to the second valve,
• wherein the valve device includes a booster valve with at least one spring-biased piston and with a vent opening, and wherein the valve device is configured to vent the discharge line in the stable state, and the vent opening points in a direction of motion of the piston or is arranged to the side thereof, and
• wherein the valve device includes a first inlet, which is connected to the feed line, a second inlet and a third inlet which is connected to the discharge line, wherein the second inlet is the control input for switching between the stable state and the activated state in response to the control signals.