A three-gear automatic transmission for electric vehicle with a brushless control-by-wire centrifugal ball arm engagement device, which comprises an input shaft (1Z), an output shaft (2Z), an input gearwheel (1), a first-gear input gearwheel (11), a second-gear input gearwheel (12), a first-gear driving gearwheel (21) and a second-gear driving gearwheel (22);
- the input gearwheel (1) being fixedly mounted on the input shaft (1Z), and normally engaged with the first-gear input gearwheel (11) and the second-gear input gearwheel (12) respectively along an outer circumference of the input gearwheel (1);
- the three-gear automatic transmission being characterized in that:
- the three-gear automatic transmission further comprises three brushless control-by-wire centrifugal ball arm engagement devices (10), a first-gear brushless electromagnet (1WT), a second-gear brushless electromagnet (2WT) and a third-gear brushless electromagnet (3WT);
- the brushless control-by-wire centrifugal ball arm engagement device (10) each comprises a thrust pressing disc (10c), a driven inner-spline hub (10d), a control-by-wire driving disc (10g), a preloading spring (10i), a centrifugal ball arm hollow disc (10j), centrifugal ball arm pins (10k), centrifugal ball arms (10l), centrifugal balls (10m), a magnetic conductive force transmitting disk (10q), centrifugal ball sockets (10r) and a drive shaft (10Z);
- the centrifugal ball arm hollow disc (10j) is rotatably supported on the drive shaft (10Z) by a bearing, and is provided with outer-spline grooves of centrifugal ball arm hollow disc (10ja) on the outer circumferential surface of one end of the centrifugal ball arm hollow disc (10j);
- the control-by-wire drive disc (10g) is arranged on the outer-spline grooves of centrifugal ball arm hollow disc (10ja) by inner-spline grooves of the control-by-wire drive disc (10g);
- the preloading spring (10i) is disposed between the end of the outer-spline grooves of centrifugal ball arm hollow disc (10ja) and the inside end face of the control-by-wire drive disc (10g);
- the control-by-wire drive disc (10g) is provided with a friction driving end face (10ga);
- the centrifugal ball arm hollow disc (10j) is provided with a plurality of centrifugal ball arm holders which are evenly arranged in the circumferential direction at the other end of the centrifugal ball arm hollow disc (10j), the centrifugal ball arm holders each having one centrifugal ball arm pin (10k) fixedly mounted thereon;
- the centrifugal ball arm (10l) has one end mounted on the intermediate journal of the centrifugal ball arm pin (10k) by a smooth bearing hole of the centrifugal ball arm (10l) and is rotatable freely around the centrifugal ball arm pin (10k);
- the centrifugal ball arm (10l) has the other end provided with one centrifugal ball socket (10r), in each of which a centrifugal ball (10m) is provided and capable of rolling freely;
- the thrust pressing disc (10c) has one end face being a smooth end surface (10ca), on which the centrifugal ball (10m) each abuts against, and further has outer-spline grooves provided on an outer circumferential surface of the thrust pressing disc (10c);
- the outer-spline grooves of the thrust pressing disc (10c) is axially in sliding engagement with the inner-spline grooves of the driven inner-spline hub (10d);
- the magnetic conductive force transmitting disk (10q) is fixedly mounted on the journal of the drive shaft (10Z) by a bearing hole of the center inner hub of magnetic conductive force transmitting disk (10qa);
- the magnetic conductive force transmitting disk (10q) is provided with an outer disc of magnetic conductive force transmitting disk (10qb);
- one brushless control-by-wire centrifugal ball arm engagement device (10), as a first-gear power transmission engagement device, is provided between the first-gear input gearwheel (11) and the first-gear driving gearwheel (21);
- one end of the drive shaft (10Z) of the brushless control-by-wire centrifugal ball arm engagement device (10) is connected to one end of the first-gear input gearwheel (11);
- the first-gear brushless electromagnet (1WT) being provided between the brushless control-by-wire centrifugal ball arm engagement device (10) and the first-gear input gearwheel (11);
- one brushless control-by-wire centrifugal ball arm engagement device (10), as a second-gear power transmission engagement device, is provided between the second-gear input gearwheel (12) and the second-gear driving gearwheel (22);
- one end of the drive shaft (10Z) of the brushless control-by-wire centrifugal ball arm engagement device (10) is connected to the second-gear input gearwheel (12);
- the second-gear brushless electromagnet (2WT) being provided between the brushless control-by-wire centrifugal ball arm engagement device (10) and the second-gear input gearwheel (12);
- one brushless control-by-wire centrifugal ball arm engagement device (10), as a third-gear power transmission engagement device, is provided between the input gearwheel (1) and the output shaft (2Z):
- one end of the drive shaft (10Z) of the brushless control-by-wire centrifugal ball arm engagement device (10) is connected to one end of the input shaft (1Z);
- the third-gear brushless electromagnet (3WT) being provided between the brushless control-by-wire centrifugal ball arm engagement device (10) and the input gearwheel (1);
- the first-gear brushless electromagnet (1WT), the second-gear brushless electromagnet (2WT) and the third-gear brushless electromagnet (3WT) are all fixedly mounted on a transmission housing by a non-magnetic conductive material.