CONTINUOUSLY VARIABLE TRANSMISSION

• US 20160009286A1
• Filed: 04/07/2014
• Published: 01/14/2016
• Est. Priority Date: 04/23/2013
• Status: Active Grant

• Current Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Original Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Inventors: Kobayashi, Tsunehiro
• Granted Patent: US 9,616,894 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60W 10/04 including control of propulsion units
• CPC Class Codes: B60W 10/101 Infinitely variable gearings
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: B60W 2510/081 Speed
• CPC Class Codes: B60W 2510/18 Braking system
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2520/105 Longitudinal acceleration
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: B60W 2710/081 Speed
• CPC Class Codes: B60W 2710/1005 Transmission ratio engaged
• CPC Class Codes: B60W 30/18027 Drive off, accelerating from standstill
• CPC Class Codes: B60W 30/18054 at stand still, e.g. engine in idling state hill holding B60W30/18118
• CPC Class Codes: B60W 30/18072 Coasting
• CPC Class Codes: F16H 29/04 in which the transmission ratio is changed by adjustment of a crank, an eccentric, a wobble-plate, or a cam, on one of the shafts
• CPC Class Codes: F16H 29/22 with automatic speed change
• CPC Class Codes: F16H 59/44 dependent on machine speed of the machine, e.g. the vehicle
• CPC Class Codes: F16H 61/66 specially adapted for continuously variable gearings control of exclusively fluid gearing F16H61/38

Abstract

A stepless transmission 1 is provided for preventing drive wheels from being driven despite the driver'"'"'s intention during vehicle deceleration. A control device 40: when the required drive force of the vehicle is 0, controls the output rotational speed Ne of a travel drive source 50 to be Ne2, and controls the transmission gear ratio i of the transmission 1 so that the transmission 1 in the case where the Ne is Ne1 changes from a first state to a second state; and when the vehicle speed V is less than a boundary speed Vgn, controls the ratio i to be a state maintaining transmission gear ratio ign that enables the first state to be maintained even during vehicle deceleration. In the second state a rotational drive force is transmitted from an input shaft 2 to an output shaft 3. In the first state the transmission is prevented.

Claims

1. A stepless transmission comprising:

an input portion to which a rotational drive force from a travel drive source is transmitted;

an output portion that transmits a rotational drive force to a drive wheel;

a transmission portion that changes the rotational drive force from the input portion, and transmits the changed rotational drive force to the output portion;

a one-way rotation blocking mechanism that includes a first element connectable to the transmission portion and a second element connectable to the output portion, and locks the first element to the second element when the first element tries to relatively rotate to one side with respect to the second element, and lets the first element idle with respect to the second element when the first element tries to relatively rotate to the other side with respect to the second element; and

a control unit that controls a transmission gear ratio of the stepless transmission,

wherein a first target rotational speed is defined, the first target rotational speed being a target of an output rotational speed of the travel drive source when a state of the stepless transmission changes from a first state in which transmission of the rotational drive force from the first element to the second element is prevented to a second state in which the rotational drive force is transmitted from the first element to the second element, and

wherein the control unit;

when a required drive force of a vehicle is 0, controls the travel drive source so that the output rotational speed of the travel drive source is a second target rotational speed lower than the first target rotational speed, and controls the transmission gear ratio of the stepless transmission to be a transmission gear ratio which is a boundary where the state of the stepless transmission in a case where the output rotational speed of the travel drive source is the first target rotational speed changes from the first state to the second state; and

when the required drive force of the vehicle is 0 and a travel speed of the vehicle is less than a predetermined speed, controls the transmission gear ratio of the stepless transmission to be a predetermined transmission gear ratio that enables the first state to be maintained even in a case where the vehicle is decelerated.

2. The stepless transmission according to claim 1, wherein the predetermined transmission gear ratio is a first transmission gear ratio when the drive wheel is braked, and a second transmission gear ratio smaller than the first transmission gear ratio when the drive wheel is not braked, and

wherein the second transmission gear ratio is larger than the transmission gear ratio which is the boundary where the state of the stepless transmission changes from the first state to the second state.

3. The stepless transmission according to claim 2, wherein the transmission gear ratio is able to be set to infinity, and the first transmission gear ratio is infinity.

4. The stepless transmission according to claim 2, wherein the control unit determines the second transmission gear ratio, based on a smaller torque out of an allowable torsion torque of the output portion when the vehicle is in a stopped state and a drive torque of the output portion which is a boundary where the vehicle changes from the stopped state to a travel state.

5. The stepless transmission according to claim 1, wherein the first element is a swing link rotatably supported by the second element,

wherein the transmission portion is made up of a plurality of lever crank mechanisms each of which converts rotation of the input portion into swinging of the swing link,

wherein the stepless transmission includes the one-way rotation blocking mechanism that locks the swing link to the output portion when the swing link tries to relatively rotate to one side with respect to the output portion, and lets the swing link idle with respect to the output portion when the swing link tries to relatively rotate to the other side with respect to the output portion, and

wherein each of the lever crank mechanisms is formed by connecting, by a connecting rod, a rotational radius adjusting mechanism capable of adjusting a rotational radius of a rotary portion rotatable about a rotational center axis of the input portion and the swing link.

6. The stepless transmission according to claim 1, wherein the control unit sets the predetermined speed to a higher speed when a deceleration of the vehicle is larger.