Brake control apparatus capable of traction control of vehicle drive wheel and having device for reducing delivery pressure of pump during the traction control

Claim 3

An apparatus according to claim 1, further comprising a master cylinder and a primary fluid passage connecting said master cylinder and said wheel brake cylinder, and wherein said low-pressure source includes a primary reservoir for supplying the fluid to said master cylinder, and said pump is connected at a delivery port thereof to said primary fluid passage, and wherein said valve device includes a first control valve disposed in a portion of said primary fluid passage between said master cylinder and a point of connection of said delivery port of said pump to said primary fluid passage, said first control valve having an open position for connecting said master cylinder and said delivery port of said pump to each other, and a closed position for disconnecting said master cylinder and said delivery port from each other, said pump delivery saving device including valve control means for placing said first control valve in said open position.

Claim 4

An apparatus according to claim 2, wherein said valve device includes a second control valve disposed in a portion of said primary fluid passage between said wheel brake cylinder and said point of connection, said second control valve having an open position for connecting said first control valve and said wheel brake cylinder to each other, and a closed position for disconnecting said first control valve and said wheel brake cylinder from each other, said valve device further including a check valve provided in a by-pass passage which by-passes said second control valve, said check valve permitting a flow of the fluid therethrough in a first direction from said wheel brake cylinder toward said master cylinder, and inhibiting a flow of the fluid therethrough in a second direction opposite to said first direction, and wherein said valve control means includes pressure hold means for placing said first control valve alternately in said open and closed positions, at a controlled duty ratio, so as to maintain the pressure of the fluid in said wheel brake cylinder at a substantially constant level.

Claim 5

Apparatus according to claim 3, wherein said low-pressure source includes a secondary reservoir in addition to said primary reservoir, and said valve device further includes a third control valve disposed in a reservoir passage which connects said secondary reservoir and said wheel brake cylinder, said third control valve having an open position for connecting said secondary reservoir and said wheel brake cylinder, and a closed position for disconnecting said secondary reservoir and said wheel brake cylinder, said pressure hold means places said first control valve in said open and closed positions while said third control valve is held in said closed position.

Claim 6

An apparatus according to claim 3, wherein said pressure hold means includes pressure determining means for determining a level at which the fluid pressure in said wheel brake cylinder is maintained, on the basis of a sum of a cumulative pressure increase time during which the fluid pressure in said wheel brake cylinder is increased, and a cumulative pressure decrease time during which the fluid pressure in said wheel brake cylinder is decreased, said pressure hold means further including duty ratio determining means for determining said duty ratio on the basis of said sum.

Claim 7

An apparatus according to claim 1, wherein said valve device includes a pressure increase valve and a pressure decrease valve, said pressure increase valve having a supply position for permitting a supply flow of the fluid delivered from said pump into said wheel brake cylinder, and a supply inhibit position for inhibiting said supply flow, said pressure decrease valve having a discharge position for permitting a discharge flow of the fluid from said wheel brake cylinder into said low-pressure source, and a discharge inhibit position for inhibiting said discharge flow, said pump delivery saving device including valve control means for placing said pressure decrease valve in said discharge position and said pressure increase valve in said supply position, in at least a portion of a time period during which said valve device is controlled by said traction controller.

Claim 8

An apparatus according to claim 6, wherein valve control means includes pressure hold means for placing said pressure decrease valve selectively in said discharge position and said discharge inhibit position at a controlled duty ratio while said pressure increase valve is held in said supply position.

Claim 9

An apparatus according to claim 1, wherein said enabling and disabling means includes temperature detecting means for detecting the temperature of said fluid, and first enabling means for enabling said pump delivery saving device to operate, if the temperature of the fluid detected by said temperature detecting means is higher than a predetermined upper limit.

Claim 10

An apparatus according to claim 1, wherein said enabling and disabling means includes time obtaining means for obtaining a length of time relating to continuation of an operation of said traction controller to control said valve device, and second enabling means for enabling said pump delivery saving device to operate, if said length of time obtained by said time obtaining means is longer than a predetermined value.

Claim 11

An apparatus according to claim 9, wherein said time obtaining means obtains, as said length of time relating to continuation of an operation of said traction controller, an operating time of said pump during the operation of said traction controller.

Claim 12

An apparatus according to claim 1, wherein said enabling and disabling means includes vehicle state detecting means for determining whether said motor vehicle is in a stuck state in which the vehicle is unable to start with said drive wheel slipping on a road surface third enabling means for enabling said pump delivery saving device to operate, if said vehicle state detecting means determines that said vehicle is placed in said stuck state.

Claim 13

An apparatus according to claim 1, wherein said pump delivery saving device includes valve control means for controlling said valve device so as to reduce the delivery pressure of said pump.

Claim 14

An apparatus according to claim 1, wherein said pump delivery saving device includes a delivery saving valve other than said valve device, for reducing the delivery pressure of said pump, and control means for controlling said delivery saving valve.

Claim 15

An apparatus according to claim 1, further comprising a master cylinder and a primary fluid passage connecting said master cylinder and said wheel brake cylinder, and wherein said low-pressure source includes a primary reservoir for supplying the fluid to said master cylinder, said apparatus further comprising anti-lock control means for selectively placing said valve device in at least said pressure increase state and said pressure decrease state, during brake application with a pressure of the fluid being applied to said wheel brake cylinder, so as to control the pressure of the fluid in said wheel brake cylinder so that amount of slip of said drive wheel is held within a predetermined range.

Claim 16

An apparatus according to claim 1, further comprising a relief passage connecting said delivery port of said pump and said low-pressure source, and a pressure relief valve provided in said relief passage, and wherein said pump delivery saving device includes a by-pass device for returning the fluid delivered from said pump to one of said low-pressure source and a suction port of the pump, while by-passing said pressure relief valve.

Claim 17

An apparatus according to claim 15, wherein said low-pressure source includes a primary reservoir for supplying the fluid to a master cylinder, and said pressure relief valve is provided between said delivery port of said pump and said master cylinder, said by-pass device including a by-pass control valve which is disposed between said delivery port of said pump and said master cylinder, in parallel connection with said pressure relief valve and a control valve of said valve device, said by-pass control valve having an open position and a closed position, said by-pass device further including control means for placing said by-pass control valve in said open position to permit the fluid to be returned to said master cylinder through said by-pass control valve.

Claim 18

An apparatus according to claim 16, further comprising a primary fluid passage connecting said wheel brake cylinder and said master cylinder, a pump passage connecting said primary fluid passage and the delivery port of said pump, and a check valve which is disposed in a portion of said pump passage between said by-pass control valve and a point of connection of said pump passage to said primary fluid passage, said check valve permitting a flow of the fluid therethrough in a first direction from said pump toward said primary fluid passage and inhibiting a flow of the fluid therethrough in a second direction opposite to said first direction.

Claim 19

An apparatus according to claim 1, further comprising a master cylinder, a primary fluid passage connecting said master cylinder and said wheel brake cylinder, a reservoir passage connected to said wheel brake cylinder, and wherein said low-pressure source includes a primary reservoir for supplying the fluid to said master cylinder, and a secondary reservoir connected to said reservoir passage, said pump being connected at a delivery port thereof to said primary fluid passage, said valve device including a first control valve disposed in a portion of said primary fluid passage between said master cylinder and a point of connection of said delivery port of said pump to said primary fluid passage, a second control valve disposed in a portion of said primary fluid passage between said point of connection and said wheel brake cylinder, and a third control valve disposed in said reservoir passage connecting said wheel brake cylinder and said secondary reservoir, said first control valve having an open position for connecting said master cylinder and said delivery port of said pump to each other and a closed position for disconnecting said master cylinder and said delivery port from each other, said second control valve having an open position for connecting said first control valve and said wheel brake cylinder to each other and a closed position for disconnecting said first control valve and said wheel brake cylinder from each other, said third control valve having an open position for connecting said wheel brake cylinder and said secondary reservoir to each other and a closed position for disconnecting said wheel brake cylinder and said secondary reservoir from each other, and wherein said pump delivery saving device includes valve control means for placing both said second and third control valves in said open position in at least a portion of a time period during which said first control valve is held in said closed position.

Claim 20

An apparatus according to claim 16, wherein said valve control means includes pressure hold means for placing said third control valve selectively in said open and closed positions at a controlled duty ratio while said second control valve is held in said open position.

Claim 21

An apparatus according to claim 1, further comprising a relief passage connecting said delivery port of the pump and the low-pressure source, and a pressure relief valve provided in the relief passage, wherein the pump delivery saving device includes a fluid circulating circuit for returning the fluid delivered from the pump to a suction port of the pump while by-passing the pressure relief valve.

Claim 22

An apparatus according to claim 1, further comprising a master cylinder, a primary fluid passage connecting said master cylinder to said wheel brake cylinder, and a secondary fluid passage for connecting said master cylinder to a secondary reservoir, and wherein said low-pressure source includes a primary reservoir for supplying said master cylinder, and said secondary reservoir, said apparatus further comprising a reservoir filling valve device which is provided in said secondary fluid passage and which has an open position for connecting said master cylinder and said secondary reservoir to each other and a closed position for disconnecting said master cylinder and said secondary reservoir from each other.

Claim 23

An apparatus according to claim 21, wherein said reservoir filling valve device includes a fourth control valve for opening and closing said secondary fluid passage, and said traction controller includes valve control means for opening said fourth control valve upon initiation of a traction control operation to control said valve device.

Claim 24

An apparatus according to claim 21, wherein said reservoir filling valve device includes a pressure relief valve which is normally placed in a closed position and is opened when a pressure of the fluid in said master cylinder becomes higher than a pressure of the fluid in said secondary reservoir by more than a predetermined amount.

Claim 25

An apparatus according to claim 21, wherein said reservoir filling valve device includes an in-flow control valve which is closed when an amount of the fluid in said secondary reservoir is larger than a predetermined value and is opened when the amount of the fluid in said secondary reservoir is smaller than said predetermined value.

Claim 26

An apparatus according to claim 1, further comprising a pump passage connecting a suction port of said pump and said low-pressure source, and wherein said pump delivery saving device includes a pump suction control valve which is disposed in said pump passage and which has an open position for connecting the suction port of the pump and the low-pressure source to each other and a closed position for disconnecting said suction port and the low-pressure source from each other, and valve control means for placing said pump suction control valve in said closed position.

Claim 27

An apparatus according to claim 1 wherein said pump delivery saving device reduces the delivery pressure of said pump while said valve device is placed in said pressure decrease state.

Claim 28

An apparatus according to claim 1, wherein said traction controller includes mode selecting means for selectively establishing one of a pressure increase mode, a pressure decrease mode and a pressure hold mode for increasing, decreasing and holding the fluid pressure in said wheel brake cylinder, said pump delivery saving device being operated to reduce the delivery pressure of said pump when at least one of said pressure decrease and hold modes is established by said mode selecting means.

Claim 29

An apparatus according to claim 1 characterized by further comprising a master cylinder, a primary fluid passage connecting said master cylinder and said wheel brake cylinder, a secondary fluid passage connecting said master cylinder and said low-pressure source, a reservoir communication valve provided in said secondary fluid passage and having an open position for connecting said master cylinder and said low-pressure source to each other and a closed position for disconnecting said master cylinder and said low-pressure source from each other, a relief passage connecting said master cylinder and a point of connection of said primary fluid passage to a delivery port of said pump, a pressure relief valve provided in said relief passage, and anti-lock control means means for controlling said valve device so as to control the pressure of the fluid in said wheel brake cylinder so that amount of slip of said wheel is held within a predetermined range, and wherein said valve device includes a master cylinder cut valve provided in said primary fluid passage and having an open position and a closed position for connecting and disconnecting said master cylinder to and from said point of connection, respectively, and a brake cylinder control valve device provided in a portion of said primary fluid passage between said master cylinder cut valve and said wheel brake cylinder, said brake cylinder control valve device including at least a pressure increase state for permitting the fluid to be fed into said wheel brake cylinder and a pressure decrease state for permitting the fluid to be discharged from said wheel brake cylinder into said low-pressure source, and wherein said point of connection of said primary fluid passage to said delivery port of said pump is located between said master cylinder cut valve and said brake cylinder control valve device, said pump being provided in a pump passage which connects said point of connection and said low-pressure source, said anti-lock control means selectively placing said brake cylinder control valve device in at least said pressure increase state and said pressure decrease state while said master cylinder cut valve and said reservoir communication valve are held in said open and closed positions, respectively, said traction control means selectively placing said brake control valve device in at least said pressure increase state and said pressure decrease state while said master cylinder cut valve and said reservoir communication valve are held in said closed and open positions, respectively, said pump delivery saving device reducing said delivery pressure of said pump in at least a portion of a time period during which said brake cylinder control valve device is placed in a state other than said pressure increase state.

Claim 30

An apparatus according to claim 28, wherein said pump delivery saving device includes means for placing said master cylinder cut valve to reduce the delivery pressure of said pump.

Claim 31

An apparatus according to claim 28, wherein said brake cylinder control valve device includes a check valve provided in a by-pass passage which connects said wheel brake cylinder and said point of connection of said primary fluid passage, said check valve permitting a flow of the fluid in a first direction from said wheel brake cylinder toward said point of connection, and inhibiting a flow of the fluid in a second direction opposite to said first direction, and wherein said pump delivery saving device comprises pressure hold means for placing at least said master cylinder cut valve alternately in said open and closed positions, at a controlled duty ratio, so as to maintain the pressure of the fluid in said wheel brake cylinder at a substantially constant level.

Claim 32

An apparatus according to claim 1, characterized by further comprising a master cylinder, a primary fluid passage connecting said master cylinder and said wheel brake cylinder, a master cylinder cut valve provided in said primary fluid passage, a by-pass passage which by-passes said master cylinder cut valve, and a check valve provided in said by-pass passage, said master cylinder cut valve having an open position and a closed position for connecting and disconnecting said master cylinder to and from a point of connection of said primary fluid passage to a delivery port of said pump, said check valve permitting a flow of the fluid in a first direction from said master cylinder toward said wheel brake cylinder, and inhibiting a flow of the fluid in a second direction opposite to said first direction.

Claim 33

An apparatus according to claim 1, wherein said electrically controlled valve is opened to reduce said delivery pressure of said pump to a level substantially equal to an atmospheric pressure.

Claim 34

An apparatus according to claim 1 wherein said electrically controlled valve is opened so that the fluid delivered from said pump is returned to a suction portion of said pump.

Claim 35

An apparatus according to claim 1, wherein said electrically controlled valve functions as part of said valve device.