Shift control device for hydrostatic continuously variable transmission

A shift control device in a hydrostatic continuously variable transmission in which a hydraulic closed circuit is formed between a swash plate type hydraulic pump and a swash plate type hydraulic motor, and a swash plate holder for supporting a motor swash plate of the hydraulic motor is tiltably supported on a stationary structure through a trunnion shaft fixedly mounted to said swash plate holder, wherein a drive shaft of a reversible electric motor is connected to the trunnion shaft through a reduction device which is constructed so as to transmit rotation of said electric motor to said trunnion shaft at a reduced speed but to be brought into a locked state when receiving a reverse load from said trunnion shaft, wherein an operating lever is secured to the trunnion shaft and is operatively connected with a piston slidably received in a stationary cylinder, and first and second oil chambers defined between said cylinder and said piston and opposed to each other with the piston sandwiched therebetween are interconnected through a hydraulic conduit, and wherein interposed in said hydraulic conduit is a control valve selectively switchable into a hold position in which said conduit is brought into a blocked state during an inoperative state of said electric motor, a decelerating position in which during normal rotation of said electric motor said conduit is brought into a state to communicate only in one direction from said first oil chamber to said second oil chamber and an accelerating position in which during reverse rotation of said electric motor the conduit is brought into a state to communicate only in one direction from said second oil chamber to said first oil chamber.

A shift control device in a hydrostatic continuously variable transmission in which a hydraulic closed circuit is formed between a swash plate type hydraulic pump and a swash plate type hydraulic motor, and a swash plate holder for supporting a motor swash plate of the hydraulic motor is tiltably supported on a stationary structure through a trunnion shaft fixedly mounted to said swash plate holder, wherein a drive shaft of a reversible electric motor is connected to the trunnion shaft through a reduction device which is constructed so as to transmit rotation of said electric motor to said trunnion shaft at a reduced speed but to be brought into a locked state when receiving a reverse load from said trunnion shaft, wherein an operating lever is secured to the trunnion shaft and is operatively connected with a piston slidably received in a stationary cylinder, and first and second oil chambers defined between said cylinder and said piston and opposed to each other with the piston sandwiched therebetween are interconnected through a hydraulic conduit, and wherein interposed in said hydraulic conduit is a control valve selectively switchable into a hold position in which said conduitis brought into a blocked state during an inoperative state of said electric motor, a decelerating position in which during normal rotation of said electric motor said conduit is brought into a state to communicate only in one direction from said first oil chamber to said second oil chamber and an accelerating position in which during reverse rotation of said electric motor the conduit is brought into a state to communicate only in one direction from said second oil chamber to said first oil chamber, and wherein when said control valve is selectively switched into said decelerating position a vibratory tilting moment of said motor swash plate acts as an urging force on said piston to urge oil to flow from said first oil chamber to said second oil chamber, and when said control valve is selectively switched into said accelerating position a vibratory tilting moment of said motor swash plate acts as an urging force on said piston to urge oil to flow from said second oil chamber to said first oil chamber.

A shift control device in a hydrostatic continuously variable transmission in which a hydraulic closed circuit is formed between a swash plate type hydraulic pump and a swash plate type hydraulic motor, and a swash plate holder for supporting a motor swash plate of the hydraulic motor is tiltably supported on a stationary structure through a trunnion shaft fixedly mounted to said swash plate holder, wherein a drive shaft of a reversible electric motor is connected to the trunnion shaft through a reduction device to selectively adjust the angle of inclination of said swash plate, said reduction device being constructed so as to transmit rotation of said electric motor to said trunnion shaft at a reduced speed but to be brought into a locked state when receiving a reverse load from said trunnion shaft, wherein during said selective adjustment of the angle of inclination of said swash plate vibratory tilting moments of the motor swash plate assist the electric motor, wherein an operating lever is secured to the trunnion shaft and is operatively connected with a piston slidably received in a stationary cylinder, and first and second oil chambers defined between said cylinder and said piston and opposed to each other with the piston sandwiched therebetween are interconnected through a hydraulic conduit, and wherein interposed in said hydraulic conduit is a control valve selectively switchable into a hold position in which said conduit is brought into a blocked state during an inoperative state of said electric motor, a decelerating position in which during normal rotation of said electric motor said conduit is brought into a state to communicate only in one direction from said first oil chamber to said second oil chamber and an accelerating position in which during reverse rotation of said electric motor the conduit is brought into a state to communicate only in one direction from said second oil chamber to said first oil chamber.

A shift control device in a hydrostatic continuously variable transmission in which a hydraulic closed circuit is formed between a swash plate type hydraulic pump and a swash plate type hydraulic motor, and a swash plate holder for supporting a motor swash plate of the hydraulic motor is tiltably supported on a stationary structure through a trunnion shaft fixedly mounted to said swash plate holder, wherein a drive shaft of a reversible electric motor is connected to the trunnion shaft through a reduction device to selectively adjust the angle of inclination of said swash plate, said reduction device being constructed so as to transmit rotation of said electric motor to said trunnion shaft at a reduced speed but to be brought into a locked state when receiving a reverse load from said trunnion shaft, wherein during said selective adjustment of the angle of inclination of said swash plate vibratory tilting moments of the motor swash plate assist the electric motor, wherein an operating lever is secured to the trunnion shaft and is operatively connected with a piston slidably received in a stationary cylinder, and first and second oil chambers defined between said cylinder and said piston and opposed to each other with the piston sandwiched therebetween are interconnected through a hydraulic conduit, and wherein interposed in said hydraulic conduit is a control valve selectively switchable into a hold position in which said conduit is brought into a blocked state during an inoperative state of said electric motor, a decelerating position in which during normal rotation of said electric motor said conduit is brought into a state to communicate only in one direction from said first oil chamber to said second oil chamber and an accelerating position in which during reverse rotation of said electric motor the conduit is brought into a state to communicate only in one direction from said second oil chamber to said first oil chamber, wherein when said control valve is selectively switched into said decelerating position a vibratory tilting moment of said motor swash plate acts as an urging force on said piston to urge oil to flow from said first oil chamber to said second oil chamber, and when said control valve is selectively switched into said accelerating position a vibratory tilting moment of said motor swash plate acts as an urging force on said piston to urge oil to flow from said second oil chamber to said first oil chamber.

A shift control device in a hydrostatic continuously variable transmission having a swash plate type hydraulically operated device in which a swash plate holder for supporting a swash plate of the hydraulically operated device is tiltably supported on a stationary structure through a trunnion shaft fixedly mounted to said swash plate holder, wherein a drive shaft of a reversible electric motor is connected to the trunnion shaft through a reduction device to selectively adjust the angle of inclination of said swash plate, said reduction device being constructed so as to transmit rotation of said electric motor to said trunnion shaft at a reduced speed but to be brought into a locked state when receiving a reverse load from said trunnion shaft, wherein during said selective adjustment of the angle of inclination of said swash plate vibratory tilting moments of the swash plate assist the electric motor, wherein means is provided to control the operation of said reversible electric motor in such a manner that the motor is actuated to move the swash plate in an accelerating direction when a number of rotation of an engine associated with the transmission and a shift ratio of the transmission are lower than respective desired levels by more than predetermined values, that the motor is actuated to move the swash plate in a decelerating direction when the number of rotation of the engine and the shift ratio are higher than said respective desired levels by more than said predetermined values, and that the motor is controlled to hold the swash plate in a current position thereof when a difference between the number of rotation of the engine and its desired level and a difference between the shift ratio and its desired level are, in respective absolute values, not higher than said predetermined values.

A shift control device in a hydrostatic continuously variable transmission having a swash plate type hydraulically operated device in which a swash plate holder for supporting a swash plate of the hydraulically operated device is tiltably supported on a stationary structure through a trunnion shaft fixedly mounted to said swash plate holder, wherein a drive shaft of a reversible electric motor is connected to the trunnion shaft through a reduction device to selectively adjust the angle of inclination of said swash plate, said reduction device being constructed so as to transmit rotation of said electric motor to said trunnion shaft at a reduced speed but to be brought into a locked state when receiving a reverse load from said trunnion shaft, wherein during said selective adjustment of the angle of inclination of said swash plate vibratory tilting moments of the swash plate assist the electric motor, and wherein means to control the operation of said reversible electric motor are provided, said means to control being switchable between a first state in which said electric motor is controlled according to a number of rotation of an engine associated with said transmission and a second state in which said electric motor is controlled according to a shift ratio of said transmission, wherein when said means to control is in said first state the motor is actuated to move the swash plate in an accelerating direction when said number of rotation of said engine is lower than a desired level by more than a predetermined value, the motor is actuated to move the swash plate in a decelerating direction when the number of rotation of the engine is higher than said desired level by more than said predetermined value, and the motor is controlled to hold the swash plate in a current position thereof when a difference between the number of rotation of the engine and its desired level is, in absolute value, not higher than said predetermined value.

A shift control device in a hydrostatic continuously variable transmission having a swash plate type hydraulically operated device in which a swash plate holder for supporting a swash plate of the hydraulically operated device is tiltably supported on a stationary structure through a trunnion shaft fixedly mounted to said swash plate holder, wherein a drive shaft of a reversible electric motor is connected to the trunnion shaft through a reduction device to selectively adjust the angle of inclination of said swash plate, said reduction device being constructed so as to transmit rotation of said electric motor to said trunnion shaft at a reduced speed but to be brought into a locked state when receiving a reverse load from said trunnion shaft, wherein during said selective adjustment of the angle of inclination of said swash plate vibratory tilting moments of the swash plate assist the electric motor, and wherein means to control the operation of said reversible electric motor are provided, said means to control being switchable between a first state in which said electric motor is controlled according to a number of rotation of an engine associated with said transmission and a second state in which said electric motor is controlled according to a shift ratio of said transmission, wherein when said means to control is in said second state the motor is actuated to move the swash plate in an accelerating direction when said shift ratio of the transmission is lower than a desired level by more than a predetermined value, the motor is actuated to move the swash plate in a decelerating direction when the shift ratio is higher than said desired level by more than said predetermined value, and the motor is controlled to hold the swash plate in a current position thereof when a difference between the shift ratio and its desired level is, in absolute value, not higher than said predetermined value.

A shift control device in a hydrostatic continuously variable transmission having a swash plate type hydraulically operated device in which a swash plate holder for supporting a swash plate of the hydraulically operated device is tiltably supported on a stationary structure through a trunnion shaft fixedly mounted to said swash plate holder, wherein a drive shaft of a reversible electric motor is connected to the trunnion shaft through a reduction device to selectively adjust the angle of inclination of said swash plate, said reduction device being constructed so as to transmit rotation of said electric motor to said trunnion shaft at a reduced speed but to be brought into a locked state when receiving a reverse load from said trunnion shaft, wherein during said selective adjustment of the angle of inclination of said swash plate vibratory tilting moments of the swash plate assist the electric motor, and wherein means to control the operation of said reversible electric motor are provided, said means to control being switchable between a first state in which said electric motor is controlled according to a number of rotation of an engine associated with said transmission and a second state in which said electric motor is controlled according to a shift ratio of said transmission, wherein said means to control comprises a detector section for detecting the travelling state of a vehicle, a logical control section operatively connected to said detector section for determining a shift control condition depending on signals from said detector section, and a drive control section operatively connected to said logical control section and said motor for outputting an actuating signal to operate said motor depending upon an output from said logical control section.

A shift control device in a hydrostatic continuously variable transmission having a swash plate type hydraulically operated device in which a swash plate holder for supporting a swash plate of the hydraulically operated device is tiltably supported on a stationary structure through a trunnion shaft fixedly mounted to said swash plate holder, wherein a drive shaft of a reversible electric motor is connected to the trunnion shaft through a reduction device to selectively adjust the angle of inclination of said swash plate, said reduction device being constructed so as to transmit rotation of said electric motor to said trunnion shaft at a reduced speed but to be brought into a locked state when receiving a reverse load from said trunnion shaft, wherein during said selective adjustment of the angle of inclination of said swash plate vibratory tilting moments of the swash plate assist the electric motor, and wherein means to control the operation of said reversible electric motor are provided, said means to control being switchable between a first state in which said electric motor is controlled according to a number of rotation of an engine associated with said transmission and a second state in which said electric motor is controlled according to a shift ratio of said transmission, wherein said means to control comprises a detector section for detecting the travelling state of a vehicle, a logical control section operatively connected to said detector section for determining a shift control condition depending on signals from said detector section, and a drive control section operatively connected to said logical control section and said motor for outputting an actuating signal to operate said motor depending upon an output from said logical control section, wherein said detector section detects a throttle opening degree, said number of rotation of said engine, the speed of said vehicle, and a setting shift ratio.