Hydraulic regenerative braking system for a vehicle

A hydraulic regenerative braking system for a vehicle, the vehicle including a shaft connected to at least one wheel, the system comprising:

• a first accumulator configured to receive fluid and store the fluid under pressure;
• a second accumulator configured to store the fluid at a pressure lower than the pressure of the fluid in the first accumulator;
• a hydraulic machine operable as a pump configured to be driven by energy received from the at least one wheel when the vehicle is braking, thereby facilitating storage of vehicle braking energy, the hydraulic machine being further operable as a motor configured to be driven by stored braking energy, thereby providing torque to the at least one wheel, the hydraulic machine being configured to pump fluid into the first accumulator when operating as a pump, and to receive fluid from the first accumulator when operating as a motor, the hydraulic machine being further configured such that the amount of fluid pumped into the first accumulator during each cycle of the hydraulic machine can be varied, and the amount of fluid received from the first accumulator during each cycle of the hydraulic machine can be varied, thereby facilitating operation of the hydraulic machine as a variable displacement pump and as a variable displacement motor, the hydraulic machine including:
• a housing including a high pressure fluid port in communication with the first accumulator, and a low pressure fluid port in communication with the second accumulator,
• a plurality of pistons, each of the pistons being configured to reciprocate within a corresponding cylinder in the housing, the pistons pumping fluid into the first accumulator when the hydraulic machine is operating as a pump, and the pistons being driven by fluid from the first accumulator when the hydraulic machine is operating as a motor,
• a cam having a plurality of lobes configured to translate rotational motion of the cam into linear motion of the pistons when the hydraulic machine is operating as a pump, and to translate linear motion of the pistons into rotational motion of the cam when the hydraulic machine is operating as a motor, and
• a valve plate including a plurality of apertures therethrough, at least one of the apertures communicating with the high pressure fluid port and at least one other of the apertures communicating with the low pressure fluid port, the valve plate being configured to connect at least one of the cylinders with the high pressure fluid port and at least one other of the cylinders with the low pressure fluid port, the valve plate being rotatable relative to the cam to vary the amount of fluid pumped into the first accumulator during each cycle when the hydraulic machine is operating as a pump, and to vary the amount of fluid received from the first accumulator during each cycle when the hydraulic machine is operating as a motor;
• and
• a control system including at least one control module, the control system being configured to receive inputs related to the operation of the vehicle, and to control operation of the hydraulic machine.

A method for hydraulic regenerative braking of a vehicle, the vehicle including a shaft connected to at least one wheel, first and second accumulators for storing and providing pressurized fluid, and further including a hydraulic machine operable as a pump configured to receive energy from the at least one wheel and pump fluid into the first accumulator, and further operable as a motor to receive pressurized fluid from the first accumulator and provide energy to the at least one wheel, the hydraulic machine including a housing including a high pressure fluid port in communication with the first accumulator, and a low pressure fluid port in communication with the second accumulator, a plurality of pistons, each of the pistons being configured to reciprocate within a corresponding cylinder in the housing, a cam for driving and being driven by the pistons, and a valve plate including a plurality of apertures therethrough, at least one of the apertures communicating with the high pressure fluid port and at least one other of the apertures communicating with the low pressure fluid port, the method comprising:

• operating the hydraulic machine as a pump during a vehicle braking event, the hydraulic machine being driven by the shaft, thereby providing pressurized fluid to at least the first accumulator to store the pressurized fluid;
• operating the hydraulic machine to control the amount of fluid provided to the first accumulator during each cycle of the hydraulic machine during the braking event, thereby controlling the displacement of the hydraulic machine when operating as a pump;
• operating the hydraulic machine as a motor during a vehicle driving event, the hydraulic machine being driven by pressurized fluid provided from at least the first accumulator, thereby providing torque to the shaft;
• operating the hydraulic machine to control the amount of fluid received from the first accumulator during each cycle of the hydraulic machine during the driving event, thereby controlling the displacement of the hydraulic machine when operating as a motor;
• positioning the valve plate such that at least one of the cylinders is connected with the high pressure fluid port and at least one other of the cylinders is connected with the low pressure fluid port;
• rotating the valve plate relative to the cam to vary the amount of fluid pumped into the first accumulator during each cycle when the hydraulic machine is operating as a pump;
• and
• rotating the valve plate relative to the cam to vary the amount of fluid received from the first accumulator during each cycle when the hydraulic machine is operating as a motor.

A hydraulic machine, comprising:

• a housing including one portion having a plurality of radially oriented cylinders disposed therein, and another portion configured to be disposed substantially around the one portion and including a tapered bore, and further including a high pressure fluid port and a low pressure fluid port;
• a plurality of pistons, each of the pistons being configured to reciprocate within a corresponding cylinder in the housing and having a corresponding piston stroke, each of the pistons including a corresponding cam follower;
• a cam disposed within the housing, and having a plurality of lobes configured to cooperate with the cam followers such that effecting a relative rotational motion between the cam and the housing effects linear motion of the pistons, and effecting linear motion of the pistons effects a relative rotational motion between the cam and the housing;
• and
• a valve plate including a plurality of apertures therethrough, at least one of the apertures communicating with the high pressure fluid port and at least one other of the apertures communicating with the low pressure fluid port, the valve plate being configured to connect at least one of the cylinders with the high pressure fluid port and at least one other of the cylinders with the low pressure fluid port, the valve plate being movable relative to the housing to effect a first transition to disconnect the at least one cylinder from the high pressure fluid port and connect it with the low pressure fluid port, and to effect a second transition to disconnect the at least one other cylinder from the low pressure fluid port and connect it with the high pressure fluid port, the valve plate being movable such that the first and second transitions can be effected at a plurality of piston positions within a corresponding piston stroke, thereby facilitating variable displacement operation of the hydraulic machine.

A hydraulic machine, comprising:

• a housing having a plurality of radially oriented cylinders disposed therein, and including a high pressure fluid port and a low pressure fluid port, the housing being configured to be substantially rotationally stationary, such that relative rotational motion between the cam and the housing is effected by rotation of the cam;
• a plurality of pistons, each of the pistons being configured to reciprocate within a corresponding cylinder in the housing and having a corresponding piston stroke, each of the pistons including a corresponding cam follower;
• a cam disposed within the housing, and having a plurality of lobes configured to cooperate with the cam followers such that effecting a relative rotational motion between the cam and the housing effects linear motion of the pistons, and effecting linear motion of the pistons effects a relative rotational motion between the cam and the housing;
• and
• a valve plate including a plurality of apertures therethrough, at least one of the apertures communicating with the high pressure fluid port and at least one other of the apertures communicating with the low pressure fluid port, the valve plate being configured to connect at least one of the cylinders with the high pressure fluid port and at least one other of the cylinders with the low pressure fluid port, the valve plate being movable relative to the housing to effect a first transition to disconnect the at least one cylinder from the high pressure fluid port and connect it with the low pressure fluid port, and to effect a second transition to disconnect the at least one other cylinder from the low pressure fluid port and connect it with the high pressure fluid port, the valve plate being movable such that the first and second transitions can be effected at a plurality of piston positions within a corresponding piston stroke, thereby facilitating variable displacement operation of the hydraulic machine.

A hydraulic machine, comprising:

• a housing having a plurality of radially oriented cylinders disposed therein, and including a high pressure fluid port and a low pressure fluid port;
• a plurality of pistons, each of the pistons being configured to reciprocate within a corresponding cylinder in the housing and having a corresponding piston stroke, each of the pistons including a corresponding cam follower;
• a cam disposed within the housing, and having a plurality of lobes configured to cooperate with the cam followers such that effecting a relative rotational motion between the cam and the housing effects linear motion of the pistons, and effecting linear motion of the pistons effects a relative rotational motion between the cam and the housing;
• a valve plate including a plurality of apertures therethrough, at least one of the apertures communicating with the high pressure fluid port and at least one other of the apertures communicating with the low pressure fluid port, the valve plate being configured to connect at least one of the cylinders with the high pressure fluid port and at least one other of the cylinders with the low pressure fluid port, the valve plate being movable relative to the housing to effect a first transition to disconnect the at least one cylinder from the high pressure fluid port and connect it with the low pressure fluid port, and to effect a second transition to disconnect the at least one other cylinder from the low pressure fluid port and connect it with the high pressure fluid port, the valve plate being movable such that the first and second transitions can be effected at a plurality of piston positions within a corresponding piston stroke, thereby facilitating variable displacement operation of the hydraulic machine;
• and
• a piston cooperating with the valve plate such that linear motion of the piston effects rotation of the valve plate relative to the cam.