Accessory drive for hybrid vehicles

A vehicle comprising:

• an internal combustion engine;
• a first hydraulic pump/motor coupled with the internal combustion engine to mechanically establish a driving connection therebetween, the first hydraulic pump/motor being operable in a pump mode to compress a hydraulic fluid under power of the internal combustion engine;
• a second hydraulic pump/motor coupled with at least one driven wheel of the vehicle to mechanically establish a driving connection therebetween, the second hydraulic pump/motor being operable in a motor mode to drive the at least one driven wheel when supplied with compressed hydraulic fluid;
• a clutch establishing the driving connection between the first hydraulic pump/motor and the internal combustion engine, the clutch being disengageable to selectively interrupt the driving connection between the first hydraulic pump/motor and the internal combustion engine;
• and
• at least one vehicle accessory device coupled to the first hydraulic pump/motor, wherein the at least one vehicle accessory device is operable under power of the internal combustion engine when the clutch is engaged and the internal combustion engine is running, and the at least one vehicle accessory device is operable directly by the first hydraulic pump/motor operating in a motor mode when the clutch is disengaged, regardless of whether or not the internal combustion engine is running,
• wherein the driving connection between the internal combustion engine and the first hydraulic pump/motor is established on a first side of the first hydraulic pump/motor, and wherein the at least one vehicle accessory device is coupled to a second side of the first hydraulic pump/motor that is remote from the first side.

A method of operating a vehicle, the method comprising:

• providing an internal combustion engine;
• providing a first hydraulic pump/motor coupled with the internal combustion engine to mechanically establish a driving connection therebetween, the driving connection being selectively interruptible by the disengagement of a clutch;
• providing a second hydraulic pump/motor coupled with at least one driven wheel of the vehicle to mechanically establish a driving connection therebetween;
• providing at least one vehicle accessory device coupled to the first hydraulic pump/motor;
• operating the vehicle in a first operating condition in which the internal combustion engine is running, the clutch is engaged, and both the first hydraulic pump/motor and the at least one vehicle accessory device are operated under power of the internal combustion engine;
• operating the vehicle in a second operating condition in which the clutch is disengaged, and the at least one vehicle accessory device is operated directly by the first hydraulic pump/motor operating in a motor mode;
• and
• providing a third hydraulic pump/motor coupled between the internal combustion engine and the first hydraulic pump/motor to establish a driving connection therebetween, the clutch being positioned between the first and third hydraulic pump/motors.

A method of operating a vehicle, the method comprising:

• providing an internal combustion engine;
• providing a first hydraulic pump/motor coupled with the internal combustion engine to mechanically establish a driving connection therebetween, the driving connection being selectively interruptible by the disengagement of a clutch;
• providing a second hydraulic pump/motor coupled with at least one driven wheel of the vehicle to mechanically establish a driving connection therebetween;
• providing at least one vehicle accessory device coupled to the first hydraulic pump/motor;
• operating the vehicle in a first operating condition in which the internal combustion engine is running, the clutch is engaged, and both the first hydraulic pump/motor and the at least one vehicle accessory device are operated under power of the internal combustion engine;
• operating the vehicle in a second operating condition in which the clutch is disengaged, and the at least one vehicle accessory device is operated directly by the first hydraulic pump/motor operating in a motor mode;
• enacting hydraulic transmission braking of the vehicle by driving the second hydraulic pump/motor with the at least one driven wheel to operate the second hydraulic pump/motor in a pumping mode to drive a hydraulic load, the hydraulic load including at least one of a pressure reduction device fluidly coupled to the second hydraulic pump/motor, the internal combustion engine in a non-running state driven by the first hydraulic pump/motor in a motoring mode, and the at least one vehicle accessory device driven by the first hydraulic pump/motor in a motoring mode;
• and
• operating the at least one vehicle accessory device with the first hydraulic pump/motor in a pump mode at a speed independent of a rotational speed of the internal combustion engine while performing the hydraulic transmission braking.