A seven-speed automatic transmission mechanism with simple configuration

Abstract

The present invention provides a seven-speed automatic transmission with a simple configuration. It includes a transmission housing, an input shaft, an output shaft, a 9-bar 2-DOF separable planetary gear train and a torque transmission device installed inside the transmission housing. The 9-bar 2-DOF separable planetary gear train includes three basic planetary gear train units arranged in sequence from the input shaft to the output shaft; the clutch in the torque transmission device connects the input shaft and the planetary gear train, the brake in the torque transmission device connects the transmission housing and the planetary gear train, and two combinations of each clutch and each brake are selectively engaged to establish seven forward gear ratios and one reverse gear ratio between the input shaft and the output shaft, and the transmission ratios of each gear are 5.5, 3.5, 1.96, 1.45, 1, 0.72, 0.61, and 4.3 respectively. The structure is simple, the step ratio between gears is reasonable, the transmission efficiency is high, the control is simple, and it is conducive to reducing the size, weight and manufacturing cost of the transmission.

Description

Technical Field

[0001] The invention belongs to the technical field of vehicle transmission, and in particular relates to a seven-speed automatic transmission mechanism with a simple configuration. Background Art

[0002] The automatic transmission is one of the core devices of automobiles and the focus of competition among countries around the world. The mechanism is the carrier for the automatic transmission to realize the motion function. Designing and inventing new mechanisms is the source and foundation for developing new automatic transmissions. The 7-speed automatic transmission mechanism is mainly composed of a planetary gear train, a clutch and a brake. The currently commonly used 7-speed automatic transmissions are developed by ZF of Germany, Aisin of Japan and Mercedes-Benz of Germany. Most of the 7-speed transmissions use the Ravigneaux planetary gear train as the core structure of the automatic transmission mechanism. For example, the 7G-Tronic 7-speed automatic transmission of Mercedes-Benz of Germany consists of two basic planetary gear train units and one Ravigneaux planetary gear train. However, the 7G-Tronic automatic transmission mechanism contains a total of four basic planetary gear train units, among which the Ravigneaux planetary gear train is a compound planetary gear train, which is difficult to manufacture and has a high cost. In addition, the mechanism contains 7 control elements, which will increase the difficulty and cost of the overall manufacturing of the automatic transmission. Summary of the invention

[0003] The purpose of the present invention is to provide a seven-speed automatic transmission with a simple configuration in view of the above-mentioned deficiencies in the prior art.

[0004] To achieve the above object, the present invention adopts the following technical solution:

[0005] The present invention provides a seven-speed automatic transmission with a simple configuration, comprising a transmission housing; an input shaft, an output shaft and a torque transmission device installed inside the transmission housing, and also comprising a 9-bar 2-DOF separable planetary gear train, wherein the 9-bar 2-DOF separable planetary gear train comprises three basic planetary gear train units arranged in sequence along the direction from the input shaft to the output shaft, namely a first basic planetary gear train unit, a second basic planetary gear train unit and a third basic planetary gear train unit, each of the basic planetary gear train units comprises a ring gear, a planetary gear, a planet carrier and a sun gear, wherein the planet carrier of the first basic planetary gear train unit is connected to the ring gear of the second basic planetary gear train unit, the planet carrier of the second basic planetary gear train unit is connected to the ring gear of the third basic planetary gear train unit, the sun gear of the second basic planetary gear train unit is connected to the sun gear of the third basic planetary gear train unit, and the planet carrier of the third basic planetary gear train unit is connected to the output shaft;

[0006] The torque transmission device comprises:

[0007] a first clutch connecting the input shaft to the sun gear of the second basic planetary gear train unit and the sun gear of the third basic planetary gear train unit respectively;

[0008] a second clutch, which connects the input shaft to the planet carrier of the second basic planetary gear train unit and the ring gear of the third basic planetary gear train unit respectively;

[0009] a first brake connected to the ring gear of the first basic planetary gear train unit;

[0010] a second brake connecting the planet carrier of the first basic planetary gear train unit and the ring gear of the second basic planetary gear train unit;

[0011] a third brake connecting the planet carrier of the second basic planetary gear train unit and the ring gear of the third basic planetary gear train unit;

[0012] a fourth brake connecting the first clutch, the sun gear of the second basic planetary gear train unit, and the sun gear of the third basic planetary gear train unit;

[0013] Two combinations of the first clutch, the second clutch, the first brake, the second brake, the third brake and the fourth brake are selectively engaged to establish seven forward speed ratios and one reverse speed ratio between the input shaft and the output shaft.

[0014] Further, the input shaft is connected to the sun gear of the first basic planetary gear train unit through a second transmission member, the planet carrier of the first basic planetary gear train unit is connected to the ring gear of the second basic planetary gear train unit through a third transmission member, the planet carrier of the second basic planetary gear train unit is connected to the ring gear of the third basic planetary gear train unit through a fifth transmission member, the sun gear of the second basic planetary gear train unit is connected to the sun gear of the third basic planetary gear train unit through a fourth transmission member, and the planet carrier of the third basic planetary gear train unit is connected to the output shaft through an output member.

[0015] Furthermore, the first clutch is connected to the fourth transmission member; and the second clutch is connected to the fifth transmission member.

[0016] Further, the first brake is connected to the first transmission member; the second brake is connected to the third transmission member; the third brake is connected to the fifth transmission member; and the fourth brake is connected to the fourth transmission member.

[0017] Furthermore, the seven-speed transmission ratios are four reduction gears, one direct gear and two overdrive gears.

[0018] Further, a first gear ratio is established between the input shaft and the output shaft by engaging the first brake and the fourth brake;

[0019] establishing a second gear ratio between the input shaft and the output shaft by engaging the first clutch and the third brake;

[0020] establishing a third gear ratio between the input shaft and the output shaft by engaging the first clutch and the second brake;

[0021] establishing a fourth gear ratio between the input shaft and the output shaft by engaging the first clutch and the first brake;

[0022] establishing a fifth gear ratio between the input shaft and the output shaft by engaging the first clutch and the second clutch;

[0023] establishing a sixth gear ratio between the input shaft and the output shaft by engaging the second clutch and the first brake;

[0024] A seventh speed ratio is established between the input shaft and the output shaft by engaging the second clutch and the second brake.

[0025] Further, a reverse gear ratio is established between the input shaft and the output shaft by engaging the first brake and the third brake.

[0026] Furthermore, the first clutch and the second clutch are multi-plate wet clutches.

[0027] Furthermore, the first brake, the second brake and the third brake are multi-disc wet brakes.

[0028] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0029] (1) The present invention provides a seven-speed automatic transmission with a simple configuration, which is composed of a 9-bar 2-DOF separable planetary gear train, including three basic planetary gear train units, two clutches and four brakes, which are composed of a total of six control elements. The structure is simple, the transmission ratio of each gear is reasonable, and the step ratio between gears is within a reasonable range. The transmission efficiency is high, the control of the clutch and the brake is simple, and the mechanism has excellent comprehensive performance. It is conducive to reducing the size, weight and manufacturing cost of the automatic transmission.

[0030] (2) The clutch and brake working states of the present invention are simple to control. When each gear is switched, only two control elements are required to work, which reduces the control difficulty of the transmission. The step ratio between the gears is stable and the gear shifting is smooth. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of a seven-speed automatic transmission of the present invention with a simple configuration;

[0032] Figure 2 This is an operational logic diagram of a seven-speed automatic transmission of a simple configuration according to the present invention.

[0033] In the figure: 1, first basic planetary gear train unit; 11, ring gear of the first basic planetary gear train unit; 12, planetary gear of the first basic planetary gear train unit; 13, planet carrier of the first basic planetary gear train unit; 14, sun gear of the first basic planetary gear train unit; 2, second basic planetary gear train unit; 21, ring gear of the second basic planetary gear train unit; 22, planetary gear of the second basic planetary gear train unit; 23, planet carrier of the second basic planetary gear train unit; 24, sun gear of the second basic planetary gear train unit; 3, third basic planetary gear train unit; 31, ring gear of the third basic planetary gear train unit; 3 2. Planetary gears of the third basic planetary gear train unit; 33. Planetary carrier of the third basic planetary gear train unit; 34. Sun gear of the third basic planetary gear train unit; 4. Torque transmission device; 41. First transmission member; 42. Second transmission member; 43. Third transmission member; 44. Fourth transmission member; 45. Fifth transmission member; 46. Output member; 5. 9-rod 2-DOF separable planetary gear train; 6. Input shaft; 7. Output shaft; C1. First clutch; C2. Second clutch; B1. First brake; B2. Second brake; B3. Third brake; B4. Fourth brake. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention clearer, the embodiments of the present invention will be further described below in conjunction with the accompanying drawings. The following is a preferred embodiment of the present invention among multiple possible embodiments, which is intended to provide a basic understanding of the present invention, but is not intended to confirm the key or decisive elements of the present invention or to limit the scope of protection.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, it can be a mechanical connection, it can be an electrical connection, it can be a direct connection, it can be an indirect connection through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] Please refer to Figure 1 An embodiment of the present invention provides a seven-speed automatic transmission with a simple configuration, including a transmission housing 8, and an input shaft 6, an output shaft 7, a 9-rod 2-degree-of-freedom separable planetary gear train 5 and a torque transmission device 4 installed inside the transmission housing 8.

[0037] The 9-rod 2-DOF separable planetary gear train 5 includes three basic planetary gear train units arranged in sequence from the input shaft 6 to the output shaft 7, namely, a first basic planetary gear train unit 1, a second basic planetary gear train unit 2 and a third basic planetary gear train unit 3.

[0038] Each basic planetary gear train unit includes a ring gear, planet gears, a planet carrier and a sun gear.

[0039] Specific:

[0040] The sun gear 14 of the first basic planetary gear train unit and the planetary gear 12 of the first basic planetary gear train unit are externally meshed for transmission, the planetary gear 12 of the first basic planetary gear train unit and the ring gear 11 of the first basic planetary gear train unit are internally meshed for transmission, and the planetary gear 12 of the first basic planetary gear train unit is rotatably supported on the planet carrier 13 of the first basic planetary gear train unit.

[0041] The sun gear 24 of the second basic planetary gear unit and the planetary gear 22 of the second basic planetary gear unit are externally meshed for transmission, the planetary gear 22 of the second basic planetary gear unit and the ring gear 21 of the second basic planetary gear unit are internally meshed for transmission, and the planetary gear 22 of the second basic planetary gear unit is rotatably supported on the planet carrier 23 of the second basic planetary gear unit.

[0042] The sun gear 34 of the third basic planetary gear train unit and the planetary gear 32 of the third basic planetary gear train unit are externally meshed for transmission, the planetary gear 32 of the third basic planetary gear train unit and the ring gear 31 of the third basic planetary gear train unit are internally meshed for transmission, and the planetary gear 32 of the third basic planetary gear train unit is rotatably supported on the planet carrier 33 of the third basic planetary gear train unit.

[0043] The planet carrier 13 of the first basic planetary gear unit is connected to the ring gear 21 of the second basic planetary gear unit, the planet carrier 23 of the second basic planetary gear unit is connected to the ring gear 31 of the third basic planetary gear unit, the sun gear 24 of the second basic planetary gear unit is connected to the sun gear 34 of the third basic planetary gear unit, and the planet carrier 33 of the third basic planetary gear unit is connected to the output shaft 7.

[0044] The torque transmission device includes two clutches and four brakes, the two clutches are respectively a first clutch C1 and a second clutch C2, and the four brakes are respectively a first brake B1, a second brake B2, a third brake B3 and a fourth brake B4.

[0045] The first clutch C1 connects the input shaft 6 to the sun gear 24 of the second basic planetary gear train unit and the sun gear 34 of the third basic planetary gear train unit respectively;

[0046] A second clutch C2, which connects the input shaft 6 to the planet carrier 23 of the second basic planetary gear train unit and the ring gear 31 of the third basic planetary gear train unit;

[0047] A first brake B1 connected to the ring gear 11 of the first basic planetary gear train unit;

[0048] A second brake B2, which connects the planet carrier 13 of the first basic planetary gear train unit and the ring gear 21 of the second basic planetary gear train unit;

[0049] A third brake B3, which connects the planet carrier 23 of the second basic planetary gear train unit and the ring gear 31 of the third basic planetary gear train unit;

[0050] Two combinations of the first clutch C1 , the second clutch C2 , the first brake B1 , the second brake B2 , the third brake B3 , and the fourth brake B4 are selectively engaged to establish seven forward speed ratios and one reverse speed ratio between the input shaft 6 and the output shaft 7 .

[0051] In this embodiment, the first basic planetary gear train unit 1, the second basic planetary gear train unit 2 and the third basic planetary gear train unit 3 form a 9-rod 2-DOF separable planetary gear train, and its structural features are specifically as follows: the input shaft 6 is connected to the sun gear 14 of the first basic planetary gear train unit through the second transmission member 42, the planet carrier 13 of the first basic planetary gear train unit is connected to the ring gear 21 of the second basic planetary gear train unit through the third transmission member 43, the planet carrier 23 of the second basic planetary gear train unit is connected to the ring gear 31 of the third basic planetary gear train unit through the fifth transmission member 45, the sun gear 24 of the second basic planetary gear train unit is connected to the sun gear 34 of the third basic planetary gear train unit through the fourth transmission member 44, and the planet carrier 33 of the third basic planetary gear train unit is connected to the output shaft 7 through the output member 46.

[0052] In this embodiment, the structural features of the two clutches and four brakes in the transmission are as follows: the first clutch C1 is connected to the fourth brake B4 through the fourth transmission member 44; the second clutch C2 is connected to the third brake B3 through the fifth transmission member 45; the first brake B1 is connected to the first transmission member 41; the second brake B2 is connected to the third transmission member 43;

[0053] The input shaft 6 is connected to the fourth transmission member 44 through the first clutch C1; the input shaft is connected to the fifth transmission member 45 through the second clutch C2, and both the fourth transmission member 44 and the fifth transmission member 45 can be used as input members. In the mechanism of the transmission, the input shaft 6 is directly connected to the second transmission member 42, so that during the entire transmission process, the second transmission member 42 always has power input. The input shaft 6 is connected to the generator through the torque converter, and the power provided by the generator is transmitted to the input shaft through the torque converter.

[0054] The output shaft 7 is connected to the vehicle drive wheels through a differential to transmit the output power to the vehicle drive wheels.

[0055] In the present embodiment, the first clutch C1 and the second clutch C2 are both wet multi-plate clutches. When the active plate and the driven plate of the clutch are pressed tightly under the action of hydraulic pressure, the clutch is engaged and is in a working state. At this time, the movable components connected to both ends of the clutch are engaged and have the same rotation speed; conversely, when the clutch is in a non-working state, the movable components connected to both ends of the clutch are separated and have different rotation speeds.

[0056] In this embodiment, the first brake B1, the second brake B2, the third brake B3 and the fourth brake B4 are all wet multi-plate brakes used to connect the movable component and the transmission case. When the brake is in a working state, the movable component is engaged with the transmission case, the movable component cannot rotate, and is in a braking state.

[0057] The seven forward gears of the present invention are four reduction gears, one direct gear and two overdrive gears, as follows:

[0058] By engaging the first brake B1 and the fourth brake B4, a first gear ratio is established between the input shaft 6 and the output shaft 7;

[0059] By engaging the first clutch C1 and the third brake B3, a second gear ratio is established between the input shaft and the output shaft;

[0060] By engaging the first clutch C1 and the second brake B2, a third gear ratio is established between the input shaft and the output shaft;

[0061] By engaging the first clutch C1 and the first brake B1, a fourth gear ratio is established between the input shaft and the output shaft;

[0062] By engaging the first clutch C1 and the second clutch C2, a fifth gear ratio is established between the input shaft and the output shaft;

[0063] By engaging the second clutch C2 and the first brake B1, a sixth gear ratio is established between the input shaft and the output shaft;

[0064] A seventh speed ratio is established between the input shaft and the output shaft by engaging the second clutch C2 and the second brake B2.

[0065] The transmission of the present invention can also achieve a reverse gear by engaging the first brake B1 and the third brake B3 to establish a reverse gear ratio between the input shaft and the output shaft.

[0066] The transmission ratio of an automatic transmission mechanism is the ratio of the rotational speed of the input member to the rotational speed of the output member. The automatic transmission in the present invention can achieve 8 different transmission ratios, i.e., 8 gears, including 7 forward gears and 1 reverse gear. Each gear can be achieved by controlling the working state of the clutch and the brake.

[0067] refer to Figure 1 And such as Figure 2 The specific implementation process of each gear ratio of the transmission is as follows:

[0068] (1) The first gear is a deceleration gear, with a transmission ratio greater than 1. The first brake B1 and the fourth brake B4 are in working state, and other clutches and brakes are in non-working state. Since the input shaft 6 is directly connected to the second transmission member 42, the second transmission member 42 rotates together with the input shaft 6 as a whole, and the second transmission member 42 is the input member. Due to the action of the brake B1 and the brake B4, the first transmission member 41 and the fourth transmission member 44 are in a braking state, and the speed is 0. The power is transmitted from the second transmission member 42. In the first basic planetary gear train unit 1, the second transmission member 42 drives the planetary gear 12 of the first basic planetary gear train unit to rotate, and then drives the third transmission member 43 to rotate; in the second basic planetary gear train unit 2, the third transmission member 43 drives the planetary gear 22 of the second basic planetary gear train unit 2 to rotate, and then drives the fifth transmission member 45 to rotate; in the third basic planetary gear train unit 3, the fifth transmission member 45 drives the planetary gear 32 of the third basic planetary gear train unit to rotate, and then drives the output member 46 to rotate, and transmits the power to the output member 46. The rotation speed of the output member 46 is lower than that of the input member (second transmission member) 42 and is in a lower first gear. Thus, a first gear transmission ratio is established between the input shaft 6 and the output shaft 7.

[0069] (2) The second gear is a deceleration gear, with a transmission ratio greater than 1. The first clutch C1 and the third brake B3 are in operation, and the other clutches and brakes are in non-operation. Due to the action of the first clutch C1 and the direct connection between the input shaft 6 and the second transmission member 42, the second transmission member 42 and the fourth transmission member 44 are both input members, and power is transmitted from the second transmission member 42 and the fourth transmission member 44 at the same time. Due to the action of the third brake B3, the fifth transmission member 45 is in a braking state, and the speed is 0. In the third basic planetary gear train unit 3, the fourth transmission member 44 drives the planetary gear 32 of the third basic planetary gear train unit to rotate, and then drives the output member 46 to rotate, and transmits power to the output member 46. The speed of the output member 46 is lower than the speed of the input member (fourth transmission member) 44, and is in the second gear with a higher speed than the first gear. As a result, a second gear transmission ratio is established between the input shaft 6 and the output shaft 7.

[0070] (3) The third gear is a deceleration gear, with a transmission ratio greater than 1. The first clutch C1 and the second brake B2 are in operation, and the other clutches and brakes are in non-operation. Due to the action of the first clutch C1 and the direct connection between the input shaft and the second transmission member 42, the second transmission member 42 and the fourth transmission member 44 are both input members, and power is transmitted from the second transmission member 42 and the fourth transmission member 44 at the same time. Due to the action of the brake B2, the third transmission member 43 is in a braking state, and the speed is 0. In the second basic planetary gear train unit 2, the fourth transmission member 44 drives the planetary gear 22 of the second basic planetary gear train unit to rotate, and then drives the fifth transmission member 45 to rotate; in the third basic planetary gear train unit 3, the fifth transmission member 45 and the fourth transmission member 44 jointly drive the planetary gear 32 of the third basic planetary gear train unit 3 to rotate, and then drives the output member 46 to rotate, and transmits power to the output member 46. The speed of the output member 46 is lower than the speed of the input member (fourth transmission member) 44, and is in the third gear with a higher speed than the second gear. As a result, a third gear transmission ratio is established between the input shaft 6 and the output shaft 7 .

[0071] (4) The 4th gear is a deceleration gear with a transmission ratio greater than 1. The first clutch C1 and the first brake B1 are in operation, and the other clutches and brakes are in non-operation. Due to the action of the first clutch C1 and the direct connection between the input shaft and the second transmission member 42, the second transmission member 42 and the fourth transmission member 44 are both input members, and power is transmitted from the second transmission member 42 and the fourth transmission member 44 at the same time. Due to the action of the first brake B1, the first transmission member 41 is in a braking state, and the speed is 0. In the first basic planetary gear train unit 1, the second transmission member 42 drives the planetary gear 12 of the first basic planetary gear train unit to rotate, and then drives the third transmission member 43 to rotate; in the second basic planetary gear train unit 2, the third transmission member 43 and the fourth transmission member 44 jointly drive the planetary gear 22 of the second basic planetary gear train unit 2 to rotate, and then drives the fifth transmission member 45 to rotate; in the third basic planetary gear train unit 3, the fourth transmission member 44 and the fifth transmission member 45 jointly drive the planetary gear 32 of the third basic planetary gear train unit to rotate, and then drive the output member 46 to rotate, and transmit power to the output member 46. The speed of the output member 46 is lower than the speed of the input member (fourth transmission member) 44 and the input member (second transmission member) 42, and is in the fourth gear which is higher than the third gear speed. Therefore, a fourth gear transmission ratio is established between the input shaft 6 and the output shaft 7.

[0072] (5) The fifth gear is a direct gear, with a transmission ratio of 1, the first clutch C1 and the first clutch C2 are in working state, and the other brakes are in non-working state. Due to the action of the first clutch C1 and the second clutch C2, and the input shaft is directly connected to the second transmission member 42, the second transmission member 42, the fourth transmission member 44 and the fifth transmission member 45 are all input members, and the power is simultaneously transmitted from the second transmission member 42, the fourth transmission member 44 and the fifth transmission member 45, driving the third basic planetary gear train unit 3 and the second basic planetary gear train unit 2 to rotate as a whole, and then driving the output member 46 to rotate, so the input member and the output member have the same rotation speed, and are in a direct gear. As a result, a fifth gear transmission ratio is established between the input shaft 6 and the output shaft 7.

[0073] (6) The 6th gear is an overdrive gear, with a transmission ratio less than 1. The second clutch C2 and the first brake B1 are in operation, and the other clutches and brakes are in non-operation. Due to the action of the second clutch C2 and the direct connection between the input shaft and the second transmission member 42, the second transmission member 42 and the fifth transmission member 45 are both input members, and power is transmitted from the second transmission member 42 and the fifth transmission member 45 at the same time. Due to the action of the first brake B1, the first transmission member 41 is in a braking state, and the speed is 0. In the first basic planetary gear train unit 1, the second transmission member 42 drives the planetary gear 12 of the first basic planetary gear train unit to rotate, and then drives the third transmission member 43 to rotate; in the second basic planetary gear train unit 2, the third transmission member 43 and the fifth transmission member 45 jointly drive the planetary gear 22 of the second basic planetary gear train unit to rotate, and then drive the fourth transmission member 44 to rotate; in the third basic planetary gear train unit 3, the fourth transmission member 44 and the fifth transmission member 45 jointly drive the planetary gear 32 of the third basic planetary gear train unit to rotate, and then drive the output member 46 to rotate, and transmit power to the output member 46. The speed of the output member 46 is greater than the speed of the input member (second transmission member) 42 and the input member (fifth transmission member) 45, and is in the sixth gear with a higher speed. Therefore, a transmission ratio of the sixth gear is established between the input shaft 6 and the output shaft 7.

[0074] (7) The 7th gear is an overdrive gear, with a transmission ratio less than 1. The second clutch C2 and the second brake B2 are in operation, and the other clutches and brakes are in non-operation. Due to the action of the clutch C2 and the direct connection between the input shaft and the second transmission member 42, the second transmission member 42 and the fifth transmission member 45 are both input members, and the power is transmitted from the second transmission member 42 and the fifth transmission member 45 at the same time. Due to the action of the brake B2, the third transmission member 43 is in a braking state, and the speed is 0. In the second basic planetary gear train unit 2, the fifth transmission member 45 drives the planetary gear 22 of the second basic planetary gear train unit to rotate, and then drives the fourth transmission member 44 to rotate; in the third basic planetary gear train unit 3, the fifth transmission member 45 and the fourth transmission member 44 jointly drive the planetary gear 32 of the third basic planetary gear train unit to rotate, and then drive the output member 46 to rotate, and transmit the power to the output member 46. The speed of the output member 46 is greater than the speed of the input member (second transmission member) 42 and the input member (fifth transmission member) 45, and is in the 7th gear with a higher speed than the 6th gear. As a result, a seventh gear transmission ratio is established between the input shaft 6 and the output shaft 7 .

[0075] (8) The 8th gear is the reverse gear, the first brake B1 and the third brake B3 are in working state, and the other clutches and brakes are in non-working state. Since the input shaft 6 is directly connected to the second transmission member 42, the second transmission member 42 rotates together with the input shaft 6 as a whole, and the second transmission member 42 is the input member. Due to the action of the first brake B1 and the third brake B3, the first transmission member 41 and the fifth transmission member 45 are in a braking state, and the speed is 0. In the first basic planetary gear train unit 1, the second transmission member 42 drives the planetary gear 12 of the first basic planetary gear train unit to rotate, and then drives the third transmission member 43 to rotate; in the second basic planetary gear train unit 2, the third transmission member 43 drives the planetary gear 22 of the second basic planetary gear train unit 2 to rotate, and then drives the fourth transmission member 44 to rotate; in the third basic planetary gear train unit 3, the fourth transmission member 44 drives the planetary gear 32 of the third basic planetary gear train unit 3 to rotate, and then drives the output member 46 to rotate, and transmits power to the output member 46. The rotational speed direction of the output member 46 is opposite to the rotational speed direction of the input member (second transmission member) 42, and is in reverse gear. Thus, a reverse gear transmission ratio is established between the input shaft 6 and the output shaft 7.

[0076] In the present invention, the characteristic parameter K of the basic planetary gear train unit is the gear ratio between the ring gear and the sun gear. The relationship between the transmission ratio of each gear and the characteristic parameter is shown in Table 1.

[0077] In order to make each gear have a higher transmission efficiency, the characteristic parameters of the three basic planetary gear train units (the first basic planetary gear train unit, the second basic planetary gear train unit, and the third basic planetary gear train unit) in the transmission are K1=1.7, K2=2.2, and K3=2.5, respectively. The transmission ratios of each gear calculated are 5.5, 3.5, 1.96, 1.45, 1, 0.72, 0.61, and -4.3, respectively. The implementation methods of each gear are summarized as follows Figure 2 shown.

[0078] Table 1. Relationship between transmission ratio and characteristic parameters

[0079]

[0080]

[0081] The clutch and brake working states of the present invention are simple to control, and only two control elements are required to work when each gear is switched, thereby reducing the control difficulty of the transmission. The step ratio between each gear is stable, and the gear shifting is smooth.

[0082] In the absence of conflict, the above embodiments and features in the embodiments may be combined with each other.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A seven-speed automatic transmission with a simple configuration, comprising a transmission housing (8); and an input shaft (6), an output shaft (7) and a torque transmission device (4) mounted inside the transmission housing, characterized in that: The invention also comprises a 9-rod 2-DOF separable planetary gear train (5), wherein the 9-rod 2-DOF separable planetary gear train (5) comprises three basic planetary gear train units arranged in sequence along the direction from the input shaft (6) to the output shaft (7), namely a first basic planetary gear train unit (1), a second basic planetary gear train unit (2) and a third basic planetary gear train unit (3), each of the basic planetary gear train units comprising a ring gear, a planetary gear, a planet carrier and a sun gear, wherein the planet carrier (13) of the first basic planetary gear train unit is fixedly connected to the ring gear (21) of the second basic planetary gear train unit, the planet carrier (23) of the second basic planetary gear train unit is fixedly connected to the ring gear (31) of the third basic planetary gear train unit, the sun gear (24) of the second basic planetary gear train unit is fixedly connected to the sun gear (34) of the third basic planetary gear train unit, and the planet carrier (33) of the third basic planetary gear train unit is connected to the output shaft (7); The torque transmission device comprises: a first clutch (C1) for connecting the input shaft (6) to the sun gear (24) of the second basic planetary gear train unit and the sun gear (34) of the third basic planetary gear train unit; a second clutch (C2) connecting the input shaft (6) to the planet carrier (23) of the second basic planetary gear train unit and the ring gear (31) of the third basic planetary gear train unit; A first brake (B1) connected to the ring gear (11) of the first basic planetary gear train unit; a second brake (B2) connecting the planet carrier (13) of the first basic planetary gear train unit and the ring gear (21) of the second basic planetary gear train unit; a third brake (B3) connecting the planet carrier (23) of the second basic planetary gear train unit and the ring gear (31) of the third basic planetary gear train unit; a fourth brake (B4) connecting the first clutch (C1), the sun gear (24) of the second basic planetary gear train unit, and the sun gear (34) of the third basic planetary gear train unit; Two combinations of the first clutch (C1), the second clutch (C2), the first brake (B1), the second brake (B2), the third brake (B3) and the fourth brake (B4) are selectively engaged to establish seven forward speed ratios and one reverse speed ratio between the input shaft (6) and the output shaft (7).

2. The seven-speed automatic transmission according to claim 1, characterized in that: The input shaft is connected to the sun gear (14) of the first basic planetary gear train unit through a second transmission member (42); the planet carrier (13) of the first basic planetary gear train unit is connected to the ring gear (21) of the second basic planetary gear train unit through a third transmission member (43); the planet carrier (23) of the second basic planetary gear train unit is connected to the ring gear (31) of the third basic planetary gear train unit through a fifth transmission member (45); the sun gear (24) of the second basic planetary gear train unit is connected to the sun gear (34) of the third basic planetary gear train unit through a fourth transmission member (44); and the planet carrier (33) of the third basic planetary gear train unit is connected to the output shaft (7) through an output member (46).

3. The seven-speed automatic transmission according to claim 2, characterized in that: The first clutch (C1) is connected to the fourth transmission member (44); the second clutch (C2) is connected to the fifth transmission member (45).

4. The seven-speed automatic transmission according to claim 3, characterized in that: The first brake (B1) is connected to the first transmission member (41); the second brake (B2) is connected to the third transmission member (43); the third brake (B3) is connected to the fifth transmission member (45); and the fourth brake (B4) is connected to the fourth transmission member (44).

5. The seven-speed automatic transmission according to claim 4, characterized in that: The seven-speed automatic transmission has seven gear ratios of four reduction gears, one direct gear and two overdrive gears.

6. The seven-speed automatic transmission according to claim 5, characterized in that: By engaging the first brake (B1) and the fourth brake (B4), a first gear ratio is established between the input shaft (6) and the output shaft (7); establishing a second gear ratio between the input shaft and the output shaft by engaging the first clutch (C1) and the third brake (B3); establishing a third gear ratio between the input shaft and the output shaft by engaging the first clutch (C1) and the second brake (B2); establishing a fourth gear ratio between the input shaft and the output shaft by engaging the first clutch (C1) and the first brake (B1); By engaging the first clutch (C1) and the second clutch (C2), a fifth gear ratio is established between the input shaft and the output shaft; establishing a sixth gear ratio between the input shaft and the output shaft by engaging the second clutch (C2) and the first brake (B1); A seventh speed ratio is established between the input shaft and the output shaft by engaging the second clutch (C2) and the second brake (B2).

7. The seven-speed automatic transmission according to claim 6, characterized in that: A reverse gear ratio is established between the input shaft and the output shaft by engaging the first brake (B1) and the third brake (B3).

8. The seven-speed automatic transmission according to claim 7, characterized in that: The first clutch (C1) and the second clutch (C2) are multi-plate wet clutches.

9. The seven-speed automatic transmission according to claim 8, characterized in that: The first brake (B1), the second brake (B2) and the third brake (B3) are multi-disc wet brakes.

10. The seven-speed automatic transmission according to claim 9, characterized in that: The first brake (B1), the second brake (B2), the third brake (B3) and the fourth brake (B4) are all fixed on the transmission housing (8).

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