A nested clutch and shift control method thereof

Abstract

The invention discloses a nested clutch and a shift control method thereof, comprising a connected clutch outer hub and a clutch piston seat, wherein a first cavity is formed between the clutch outer hub and the clutch piston seat, a C2 clutch is arranged in the first cavity, and the pressure of two piston cavities of the nested clutch is controlled separately, so that the oil pressure in the two piston cavities is no longer just a single oil filling and oil draining during the gear shifting process. When the C2 piston cavity of the C2 piston needs to drain oil, the pressure is first reduced to a value consistent with the pressure in the C1 piston cavity of the C1 piston, and at the same time, the pressure in the C1 piston cavity is appropriately increased, so that the C2 piston is gradually separated from the friction plate to achieve the purpose of disconnecting power transmission, and the clutch outside the nested clutch is synchronously filled with oil. When the vehicle switches gears during normal driving, the power can be stably output, thereby solving the technical problem of power interruption in the gear shifting process of the hydraulic automatic transmission in the prior art.

Description

Technical Field

[0001] The invention belongs to the field of automobile transmissions and relates to a shift control method, in particular to a nested clutch and a shift control method thereof. Background Art

[0002] In a hydraulic automatic transmission, the clutch is the main shifting element and plays a vital role. The gear shift is completed by disconnecting and connecting different clutches to ensure the normal function of the hydraulic transmission. Due to the limitations of the internal structure of the transmission and the layout of the transmission line clutch, a nested clutch structure is adopted. The so-called nested structure is that the pistons of two clutches, one large and one small, are installed together, and the small piston is installed inside the large piston. The large piston is limited by the piston back plate, and the small piston is limited by the balance piston. Both pistons can move when subjected to oil pressure, so that the piston can press the friction plate to engage the clutch. The piston cavity of the large piston is composed of the outer end face of the piston and the outer hub of the clutch, and the outer end face of the small piston and the inner end face of the large piston constitute the piston cavity of the small piston, that is, the volume of the piston cavity of the small piston will be affected by the position of the large piston. The two piston cavities of the large and small pistons are controlled by different hydraulic oil circuits. The advantages of this structure are that the high integration can save more space, and the structure is relatively simple and easy for workers to assemble. However, there are also disadvantages that the pressure control of the two piston cavities is unstable and the pressures of the two piston cavities affect each other.

[0003] When shifting, the hydraulic automatic transmission needs to control the engagement and disengagement of different clutches, and the control of the piston chamber oil pressure directly affects the response speed of the clutch engagement and disengagement, the engagement time and other parameters. These parameters further determine the shift quality of the hydraulic automatic transmission, that is, whether the shift is smooth, whether the shift time is too long, and whether the shift response is timely. These factors will directly feedback to the driver's intuitive feeling. Therefore, the control of the clutch oil pressure will directly affect the working performance of the entire hydraulic transmission.

[0004] However, due to the existence of the nested clutch structure, the pressures between the large and small piston chambers will affect each other. That is, during the process of filling the piston chamber of the large piston with oil, if there is no oil pressure in the small piston chamber, the small piston will be moved with it. When the small piston moves to the limit position, the internal pressure of the piston chamber of the large piston can be established steadily; if there is already oil pressure in the small piston chamber, the filling oil pressure in the large piston chamber needs to be greater than the existing oil pressure in the small piston chamber to push the movement of the large piston. And in the process of filling the piston chamber of the small piston with oil, if there is no oil pressure in the large piston chamber, the large piston must also be pushed to move first. When the large piston moves to the limit position, the internal pressure of the piston chamber of the small piston can be established steadily; if there is already oil pressure in the large piston chamber, the filling oil pressure in the small piston chamber needs to be less than the existing oil pressure in the large piston chamber to not affect the position of the large piston and the engagement of the friction plate of the large piston chamber. The pressure relief process is exactly the opposite of the oil filling process, and the pressure change process between the two pistons will not be repeated.

[0005] In the shifting process of hydraulic automatic transmission, the gear position is usually formed by the combination of two clutches. For example, the nested clutch structure mentioned above is composed of two sets of clutches. When both the large and small pistons are in the oil-filled state, that is, when the pistons press the friction plate clutches together, a set of gears can be formed, which is usually set to the 6th gear. When switching to the next gear, that is, the 7th gear, the clutch controlled by the large piston needs to be converted from the engaged state to the disconnected state, and the piston cavity of the large piston needs to drain oil to reduce the pressure. The piston cavity of the small piston needs to keep the piston cavity pressure unchanged during this process, and the other clutch needs to start to engage at the same time. In the actual shift oil pressure control, the pressure in the piston cavity of the large piston is usually directly released, causing the piston cavity pressure of the small piston to shake, resulting in insufficient pressure for the small piston to instantly press the friction plate. This is reflected in the driving experience of the whole vehicle, that is, when the 6th gear is switched to the 7th gear, the power output will be inconsistent and the vehicle will be frustrated. Summary of the invention

[0006] In view of the deficiencies in the prior art, the object of the present invention is to provide a nested clutch and a shift control method thereof to solve the technical problem of power interruption during the shifting process of the hydraulic automatic transmission in the prior art.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0008] A nested clutch, comprising a clutch outer hub and a clutch piston seat connected to each other, a first cavity being formed between the clutch outer hub and the clutch piston seat, a C2 clutch being arranged in the first cavity, the C2 clutch comprising a C2 piston, a C1 clutch being arranged on the inner wall of the axial front end of the C2 piston, the C1 clutch comprising a C1 piston, a balance piston being arranged on the inner wall of the axial rear end of the C2 piston; the axial rear end of the C1 piston passing through the balance piston;

[0009] A turbine shaft is arranged at the center of the clutch piston seat, a first thrust bearing is arranged at the axial rear end of the clutch piston seat, a C1 clutch outer hub spline sleeve and a C1 clutch outer hub fixedly connected in radial direction are mounted on the first thrust bearing; a second thrust bearing is arranged at the axial rear end of the C1 clutch outer hub spline sleeve, a C2 clutch inner hub drive shaft and a C2 clutch inner hub fixedly connected in radial direction are mounted on the second thrust bearing; a third thrust bearing is arranged at the axial rear end of the C2 clutch inner hub drive shaft, a clutch output disc spline sleeve and a clutch output disc fixedly connected in radial direction are mounted on the third thrust bearing;

[0010] A C2 piston return spring is arranged in the annular groove formed by the clutch outer hub and the C2 piston, one end of the C2 piston return spring contacts the inner wall of the annular groove, and the other end of the C2 piston return spring is arranged with a C2 piston back plate;

[0011] A C1 piston return spring is arranged in the annular groove formed by the C2 piston and the C1 piston, one end of the C1 piston return spring contacts the inner wall of the annular groove, and the other end contacts the axial front end surface of the balance piston;

[0012] The C2 piston is provided with a plurality of C2 friction plate groups; each C2 friction plate group comprises a first C2 friction plate and a second C2 friction plate arranged in sequence along the axial direction, the first C2 friction plate is clearance-matched with the clutch outer hub; the second C2 friction plate is clearance-matched with the C2 clutch inner hub;

[0013] The C1 piston is provided with a plurality of C1 friction plate groups, and a C1 friction plate back plate is provided at the axial rear end of the C1 friction plate group; each C1 friction plate group comprises a first C1 friction plate and a second C1 friction plate sequentially arranged along the axial direction, and the first C1 friction plate is loosely matched with the clutch outer hub; the second C1 friction plate is loosely matched with the C2 clutch inner hub;

[0014] The clutch piston seat is provided with a C2 piston chamber oil inlet passage, which connects the C2 piston chamber formed by the clutch outer hub, the C2 piston and the clutch piston seat and a pressure source; the clutch piston seat is provided with a C1 piston chamber oil inlet passage, which connects the C1 piston chamber formed by the C2 piston, the C1 piston and the clutch piston seat and a pressure source.

[0015] The present invention also includes the following technical features:

[0016] The outer wall and inner wall of the C2 piston are respectively provided with a C2 piston outer sealing ring and a C2 piston inner sealing ring; the outer wall and inner wall of the C1 piston are respectively provided with a C1 piston outer sealing ring and a C1 piston inner sealing ring; the outer wall of the balancing piston is provided with a balancing piston sealing ring.

[0017] A C2 piston back plate elastic retaining ring is arranged on the inner wall of the clutch outer hub at the axial rear end of the C2 piston back plate.

[0018] A balancing piston elastic retaining ring is arranged on the inner wall of the clutch piston seat at the axial rear end of the balancing piston.

[0019] A clutch output disc elastic retaining ring is arranged on the inner wall of the clutch outer hub at the axial rear end of the clutch output disc.

[0020] A C2 friction plate group elastic retaining ring is arranged on the inner wall of the clutch outer hub at the axial rear end of the plurality of C2 friction plate groups.

[0021] A C1 friction plate back plate elastic retaining ring is arranged on the inner wall of the clutch piston seat at the axial rear end of the C1 friction plate back plate.

[0022] The balancing piston is provided with a plurality of rectangular holes evenly distributed along the circumferential direction, and the axial rear end of the C2 piston is arranged in the rectangular hole.

[0023] A shift control method, based on the nested clutch and the B1 clutch, specifically comprises the following steps:

[0024] Step 1: When the C2 piston chamber and the C1 piston chamber reach their respective given working pressures, the C1 clutch and the C2 clutch are both engaged, and the hydraulic automatic transmission forms a middle gear;

[0025] Step 2: The transmission control unit sends a shift signal, and each clutch is separated or engaged according to the shift logic table;

[0026] If the shift signal is to switch to a higher gear, the C1 clutch is disengaged and the B1 clutch is engaged; if the shift signal is to switch to a lower gear, the C2 clutch is disengaged and the B1 clutch is engaged.

[0027] The C1 clutch disengagement and B1 clutch engagement specifically include the following steps:

[0028] S1, gradually reduce the pressure of the C1 piston chamber, so that the pressing force of the C1 piston gradually decreases, and the torque transmitted by the C1 clutch gradually decreases; at the same time, the B1 clutch starts to fill with oil and reduce the pressure of the C2 piston chamber;

[0029] S2, when the B1 clutch reaches the engagement point pressure, the B1 clutch begins to gradually engage and start to transmit torque, the pressure of the C1 piston chamber decreases to below the engagement point pressure, the C1 clutch no longer transmits torque and maintains a certain pressure;

[0030] S3, when the B1 clutch is fully engaged and the power transmission gradually stabilizes, the pressure of the C2 piston chamber is restored to the pressure of the intermediate gear;

[0031] S4, when the C1 piston chamber is completely depressurized, the C1 piston returns to the free position under the force of the C1 piston return spring;

[0032] S5, when the B1 clutch and the C2 clutch are fully engaged, the power is output stably and the gear shift is completed.

[0033] The C2 clutch disengagement and the B1 clutch engagement specifically include the following steps:

[0034] P1, gradually increase the pressure of C1 piston chamber, then gradually reduce the pressure of C2 piston chamber;

[0035] P2, B1 clutch starts to fill with oil. When B1 clutch reaches the engagement point pressure and gradually engages to start transmitting torque, the pressure in C2 piston chamber decreases to below the engagement point pressure. C2 clutch no longer transmits torque and maintains a certain pressure.

[0036] P3, when the B1 clutch is fully engaged and the power transmission gradually stabilizes, the pressure in the C1 piston chamber is restored to the pressure at the intermediate gear;

[0037] P4, when the C2 piston chamber is completely depressurized, the C2 piston returns to the free position under the force of the C2 piston return spring;

[0038] P5, when the B1 clutch and the C1 clutch are fully engaged, the power is output stably and the gear shift is completed.

[0039] Compared with the prior art, the present invention has the following beneficial technical effects:

[0040] (I) In the present invention, the pressures of the two piston chambers of the nested clutch in the hydraulic automatic transmission are controlled separately, so that the oil pressures in the two piston chambers are no longer simply filled with oil or drained during the gear shifting process. When the C2 piston chamber of the C2 piston needs to drain oil, the pressure is first reduced to a value consistent with the pressure in the C1 piston chamber of the C1 piston, and at the same time, the pressure in the C1 piston chamber is appropriately increased, so that the C2 piston and the friction plate are gradually separated to achieve the purpose of disconnecting the power transmission. At the same time, the clutch outside the nested clutch is synchronously filled with oil, and the previous control method is still maintained, so that when the vehicle switches gears during normal driving, the power can be output stably, the sense of frustration is reduced, and the discomfort of the driver and passengers is reduced, thereby solving the technical problem of power interruption in the hydraulic automatic transmission during the gear shifting process in the prior art.

[0041] (II) The present invention does not change the shifting logic and control method of other clutches, but only controls the special structure of the nested clutch, and has strong compatibility and applicability.

[0042] (III) The present invention can reduce the sliding time during the gear shifting process and can effectively improve the durability of the friction plate. In addition, the present invention can avoid the situation in which the clutch is not separated in time during the gear shifting process, resulting in the simultaneous engagement of three clutches and damage to the hydraulic automatic transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a structural schematic diagram of the nested clutch of the present invention;

[0044] Figure 2 It is a partial enlarged view of the nested clutch of the present invention;

[0045] Figure 3 A three-dimensional schematic diagram of a balancing piston in a nested clutch of the present invention;

[0046] Figure 4 It is a schematic diagram of the states of each clutch of the hydraulic automatic transmission of the present invention when in sixth gear;

[0047] Figure 5 It is a schematic diagram of the states of various clutches of the hydraulic automatic transmission of the present invention when in seventh gear;

[0048] Figure 6 It is a schematic diagram of the states of each clutch when the hydraulic automatic transmission of the present invention is in fifth gear.

[0049] The meanings of the numbers in the figure are: 1-clutch outer hub, 2-C2 piston, 3-C2 piston outer sealing ring, 4-C2 piston return spring, 5-C2 piston back plate, 6-C2 piston back plate elastic retaining ring, 7-C2 friction plate group, 8-C2 friction plate group elastic retaining ring, 9-clutch output plate, 10-clutch output plate elastic retaining ring, 11-C2 piston inner sealing ring, 12-C1 piston, 13-C1 piston outer sealing ring, 14-C1 piston return spring, 15-balance piston, 16-balance piston elastic retaining ring, 17-C1 friction plate group, 18-C1 friction Wiper back plate, 19-C1 friction plate back plate elastic retaining ring, 20-C1 piston inner sealing ring, 21-clutch piston seat, 22-balance piston sealing ring, 23-C1 clutch outer hub, 24-C2 clutch inner hub, 25-clutch output plate spline sleeve, 26-C2 clutch inner hub drive shaft, 27-C1 clutch outer hub spline sleeve, 28-turbine shaft, 29-first thrust bearing, 30-C2 piston chamber, 31-C1 piston chamber, 32-C2 piston chamber oil inlet channel, 33-C1 piston chamber oil inlet channel, 34-second thrust bearing, 35-third thrust bearing.

[0050] The specific contents of the present invention are further explained in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0051] It should be noted that, unless otherwise specified, all components in the present invention are components known in the art.

[0052] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0053] The present invention provides a nested clutch, comprising a clutch outer hub 1 and a clutch piston seat 21 connected to each other, a first cavity is formed between the clutch outer hub 1 and the clutch piston seat 21, a C2 clutch is arranged in the first cavity, the C2 clutch comprises a C2 piston 2, a C1 clutch is arranged on the inner wall of the axial front end of the C2 piston 2, the C1 clutch comprises a C1 piston 12, a balance piston 15 is arranged on the inner wall of the axial rear end of the C2 piston 2; the axial rear end of the C1 piston 12 passes through the balance piston 15;

[0054] A turbine shaft 28 is arranged at the center of the clutch piston seat 21, a first thrust bearing 29 is arranged at the axial rear end of the clutch piston seat 21, and a C1 clutch outer hub spline sleeve 27 and a C1 clutch outer hub 23 which are fixedly connected in radial direction are mounted on the first thrust bearing 29; a second thrust bearing 34 is arranged at the axial rear end of the C1 clutch outer hub spline sleeve 27, and a C2 clutch inner hub drive shaft 26 and a C2 clutch inner hub 24 which are fixedly connected in radial direction are mounted on the second thrust bearing 34; a third thrust bearing 35 is arranged at the axial rear end of the C2 clutch inner hub drive shaft 26, and a clutch output disc spline sleeve 25 and a clutch output disc 9 which are fixedly connected in radial direction are mounted on the third thrust bearing 35;

[0055] A C2 piston return spring 4 is arranged in the annular groove formed by the clutch outer hub 1 and the C2 piston 2, one end of the C2 piston return spring 4 contacts the inner wall of the annular groove, and a C2 piston back plate 5 is arranged at the other end of the C2 piston return spring 4;

[0056] A C1 piston return spring 14 is arranged in the annular groove formed by the C2 piston 2 and the C1 piston 12. One end of the C1 piston return spring 14 contacts the inner wall of the annular groove, and the other end contacts the axial front end surface of the balance piston 15.

[0057] A plurality of C2 friction plate groups 7 are arranged on the C2 piston 2; each C2 friction plate group 7 includes a first C2 friction plate and a second C2 friction plate arranged in sequence along the axial direction, the first C2 friction plate is clearance-matched with the clutch outer hub 1; the second C2 friction plate is clearance-matched with the C2 clutch inner hub;

[0058] A plurality of C1 friction plate groups 17 are arranged on the C1 piston 12, and a C1 friction plate back plate 18 is arranged at the axial rear end of the C1 friction plate group 17; each C1 friction plate group 17 includes a first C1 friction plate and a second C1 friction plate arranged in sequence along the axial direction, and the first C1 friction plate is clearance-matched with the clutch outer hub 1; the second C1 friction plate is clearance-matched with the C2 clutch inner hub;

[0059] A C2 piston chamber oil inlet passage 32 is provided on the clutch piston seat 21, and the C2 piston chamber oil inlet passage 32 connects the C2 piston chamber 30 formed by the clutch outer hub 1, the C2 piston 2 and the clutch piston seat 21 and the pressure source; a C1 piston chamber oil inlet passage 33 is provided on the clutch piston seat 21, and the C1 piston chamber oil inlet passage 33 connects the C1 piston chamber 31 formed by the C2 piston 2, the C1 piston 12 and the clutch piston seat 21 and the pressure source.

[0060] In the above technical solution, the pressure of the two piston chambers of the nested clutch in the hydraulic automatic transmission is controlled separately, so that the oil pressure in the two piston chambers is no longer just a single filling and draining of oil during the gear shifting process. When the C2 piston chamber 30 of the C2 piston needs to drain oil, the pressure is first reduced to the same level as the pressure in the C1 piston chamber 31 of the C1 piston, and the pressure in the C1 piston chamber 31 is appropriately increased, so that the C2 piston and the friction plate are gradually separated to achieve the purpose of disconnecting the power transmission. At the same time, the B1 clutch located outside the nested clutch is filled with oil synchronously, and it still maintains the previous control method, so that when the vehicle switches gears during normal driving, the power can be output stably, reducing the sense of frustration and reducing the discomfort of the driver and passengers, and solving the technical problem of power interruption in the hydraulic automatic transmission during the gear shifting process in the prior art.

[0061] The outer wall and inner wall of the C2 piston 2 are respectively provided with a C2 piston outer sealing ring 3 and a C2 piston inner sealing ring 11; the outer wall and inner wall of the C1 piston 12 are respectively provided with a C1 piston outer sealing ring 13 and a C1 piston inner sealing ring 20; the outer wall of the balancing piston 15 is provided with a balancing piston sealing ring 22.

[0062] In the above technical solution, the C2 piston outer seal ring 3, the C2 piston inner seal ring 11, the C1 piston outer seal ring 13, the C1 piston inner seal ring 20 and the balance piston seal ring 22 jointly ensure the sealing of the C2 clutch and the C1 clutch.

[0063] A C2 piston back plate elastic retaining ring 6 is arranged on the inner wall of the clutch outer hub 1 at the axial rear end of the C2 piston back plate 5 .

[0064] In the above technical solution, the C2 piston back plate elastic retaining ring 6 is used to axially limit the C2 piston back plate 5.

[0065] A balancing piston elastic retaining ring 16 is arranged on the inner wall of the clutch piston seat 21 at the axial rear end of the balancing piston 15 .

[0066] In the above technical solution, the balancing piston elastic retaining ring 16 is used to axially limit the balancing piston 15 .

[0067] A clutch output disc elastic retaining ring 10 is arranged on the inner wall of the clutch outer hub 1 at the axial rear end of the clutch output disc 9 .

[0068] In the above technical solution, the clutch output disc elastic retaining ring 10 axially limits the entire clutch assembly.

[0069] A C2 friction plate group elastic retaining ring 8 is arranged on the inner wall of the clutch outer hub 1 at the axial rear end of the plurality of C2 friction plate groups 7 .

[0070] In the above technical solution, the C2 friction plate group elastic retaining ring 8 is used to axially limit the C2 friction plate group 7.

[0071] A C1 friction plate back plate elastic retaining ring 19 is provided on the inner wall of the clutch piston seat 21 at the axial rear end of the C1 friction plate back plate 18 .

[0072] In the above technical solution, the back plate elastic retaining ring 19 is used to axially limit the C2 friction plate group 7.

[0073] A plurality of rectangular holes evenly distributed along the circumferential direction are formed on the balancing piston 15 , and the axial rear end of the C2 piston 2 is arranged in the rectangular hole.

[0074] In the above technical solution, the rectangular hole is used to realize the plug-in setting of the balance piston 15 and the C2 piston 2.

[0075] The present invention also provides a shift control method based on a nested clutch and a B1 clutch, which specifically includes the following steps:

[0076] Step 1: When the C2 piston chamber 30 and the C1 piston chamber 31 reach their respective given working pressures, the C1 clutch and the C2 clutch are both engaged, and the hydraulic automatic transmission forms a middle gear;

[0077] Step 2: The transmission control unit sends a shift signal, and each clutch is separated or engaged according to the shift logic table;

[0078] If the shift signal is to switch to a higher gear, the C1 clutch is disengaged and the B1 clutch is engaged; if the shift signal is to switch to a lower gear, the C2 clutch is disengaged and the B1 clutch is engaged.

[0079] In the above technical solution, the C2 piston 2 will be in different positions according to the different pressures it is subjected to. When the pressure reaches a certain limit, it will overcome the spring force of the C2 piston return spring 4 and be in a fixed position and press the C2 friction plate group 7, thereby realizing the engagement and transmission of power of the C2 clutch.

[0080] Similarly, the C1 piston 12 will be in different positions according to the pressure it receives. When the pressure reaches a certain limit, it will overcome the spring force of the C1 piston return spring 14 and be in a fixed position and press the C1 friction plate group 17, thereby realizing the C1 clutch engagement and power transmission. Since the two pistons are in different positions according to the different pressures received by the piston chambers, the changes in the pressure of each piston chamber are difficult to control during gear shifting, which will affect the quality of gear shifting.

[0081] The pressure of the two piston chambers of the nested clutch in the hydraulic automatic transmission is controlled separately, so that the oil pressure in the two piston chambers is no longer just a single filling and draining of oil during the gear shifting process. When the C2 piston chamber 30 of the C2 piston needs to drain oil, the pressure is first reduced to the same level as the pressure in the C1 piston chamber 31 of the C1 piston, and the pressure in the C1 piston chamber 31 is appropriately increased, so that the C2 piston and the friction plate are gradually separated to achieve the purpose of disconnecting power transmission. At the same time, the B1 clutch located outside the nested clutch is filled with oil synchronously, and it still maintains the previous control method, so that when the vehicle switches gears during normal driving, the power can be output stably, reducing the sense of frustration and reducing the discomfort of the driver and passengers, and solving the technical problem of power interruption in the hydraulic automatic transmission during the gear shifting process in the prior art.

[0082] The shift logic table in this scheme is shown in Table 1:

[0083] Table 1

[0084] Gear Low gear Middle gear High gear C1 clutch status Combination Combination Separation C2 clutch status Separation Combination Combination B1 clutch status Combination Separation Combination

[0085] Specifically, the C1 clutch is disengaged and the B1 clutch is engaged, including the following steps:

[0086] S1, gradually reduce the pressure of the C1 piston chamber 31, so that the pressing force of the C1 piston 12 gradually decreases, and the torque transmitted by the C1 clutch gradually decreases; at the same time, the B1 clutch starts to fill with oil and reduce the pressure of the C2 piston chamber 30;

[0087] S2, when the B1 clutch reaches the engagement point pressure, the B1 clutch begins to gradually engage and start to transmit torque, the pressure of the C1 piston chamber 31 decreases to below the engagement point pressure, the C1 clutch no longer transmits torque and maintains a certain pressure;

[0088] S3, when the B1 clutch is fully engaged and the power transmission gradually stabilizes, the pressure of the C2 piston chamber 30 is restored to the pressure of the intermediate gear;

[0089] S4, when the C1 piston chamber 31 is completely depressurized, the C1 piston 12 returns to the free position under the force of the C1 piston return spring 14;

[0090] S5, when the B1 clutch and the C2 clutch are fully engaged, the power is output stably and the gear shift is completed.

[0091] In the above technical solution, the pressure of the C2 piston chamber 30 is reduced to prevent the pressing force of the C2 piston 2 from suddenly increasing due to the reduction of the C1 piston chamber 31, thereby preventing the C2 friction plate group 7 from being damaged.

[0092] Specifically, the C2 clutch is disengaged and the B1 clutch is engaged, including the following steps:

[0093] P1, gradually increasing the pressure of the C1 piston chamber 31, and then gradually reducing the pressure of the C2 piston chamber 30;

[0094] P2, B1 clutch starts to fill with oil. When B1 clutch reaches the engagement point pressure and gradually engages to start transmitting torque, the pressure of C2 piston chamber 30 decreases to below the engagement point pressure, C2 clutch no longer transmits torque and maintains a certain pressure;

[0095] P3, when the B1 clutch is fully engaged and the power transmission gradually stabilizes, the pressure of the C1 piston chamber 31 is restored to the pressure of the intermediate gear;

[0096] P4, when the C2 piston chamber 30 is completely depressurized, the C2 piston 2 returns to the free position under the force of the C2 piston return spring 4;

[0097] P5, when the B1 clutch and the C1 clutch are fully engaged, the power is output stably and the gear shift is completed.

[0098] In the above technical solution, the pressure of the C1 piston chamber 31 is gradually increased, and then the pressure of the C2 piston chamber 30 is gradually reduced, so as to avoid the pressure change effect caused by the change in volume of the C1 piston chamber 31 due to the movement of the C2 piston 2.

[0099] Example:

[0100] This embodiment provides a shift control method, which is as follows:

[0101] like Figure 4 As shown, when the C1 piston chamber 30 and the C2 piston chamber 31 both reach their respective given working pressures, that is, when the C1 and C2 clutches are both engaged, the hydraulic automatic transmission can form a sixth gear. The engagement of the C2 clutch can allow the engine power to be transmitted to the output end through the welded assembly of the C2 clutch inner hub 24 and the C2 clutch inner hub drive shaft 26. The engagement of the C1 clutch can allow the engine power to be transmitted to the output end through the welded assembly of the C1 clutch outer hub 23 and the C1 clutch outer hub spline sleeve 27. The engagement and separation of different clutches can change the power transmission route to form different gears of the hydraulic transmission.

[0102] like Figure 5 As shown, when the hydraulic transmission needs to switch from the sixth gear to the seventh gear, the C1 clutch needs to be switched from the engaged state to the disengaged state, the C2 clutch pressure remains in the engaged state unchanged, and the B1 clutch is switched from the disengaged state to the engaged state, wherein the B1 clutch adopts an ordinary clutch.

[0103] First, the pressure of the C1 piston chamber 30 is gradually reduced, so that the pressing force of the C1 piston 12 is gradually reduced, and the torque transmitted by the C1 clutch is gradually reduced. At the same time, the other clutch B1 starts to fill with oil. Then the pressure of the C2 piston chamber 31 is reduced to prevent the pressing force of the C2 piston 2 from suddenly increasing due to the reduction of the C1 piston chamber 30, thereby damaging the C2 friction plate group 7. When the B1 clutch reaches the engagement point pressure and gradually engages to start transmitting torque, the pressure of the C1 piston chamber 30 is reduced to below the engagement point pressure, so that the C1 clutch no longer transmits torque, and then maintains a certain pressure. As the B1 clutch engages, the power transmission gradually stabilizes. At this time, the pressure of the C2 piston chamber 31 before the gear shift, that is, the pressure in the sixth gear, is restored. The C1 piston chamber 30 is completely depressurized, and the C1 piston 12 returns to the free position under the action of the C1 piston return spring 14. The B1 and C2 clutches are fully engaged, the power is output stably, and the transmission shifts from the sixth gear to the seventh gear.

[0104] When switching from the seventh gear to the sixth gear, the C1 clutch needs to be switched from the disengaged state to the engaged state, the C2 clutch pressure remains in the engaged state, and the B1 clutch is switched from the engaged state to the disengaged state. The control process of the piston chamber pressure is opposite to that of the sixth gear to the seventh gear.

[0105] like Figure 6 As shown, when the hydraulic transmission needs to switch from the sixth gear to the fifth gear, the C2 clutch needs to be switched from the engaged state to the disengaged state, the C1 clutch pressure remains in the engaged state unchanged, and the B1 clutch is switched from the disengaged state to the engaged state.

[0106] First, the pressure of the C1 piston chamber 30 is appropriately increased, and then the pressure of the C2 piston chamber 31 is gradually reduced. This can avoid the pressure change caused by the change in the volume of the C1 piston chamber 30 due to the movement of C22. Another set of clutches B1 begins to fill with oil. When the B1 clutch reaches the engagement point pressure and gradually engages to start transmitting torque, the pressure of the C2 piston chamber 31 is reduced to below the engagement point pressure, so that the C2 clutch no longer transmits torque, and then maintains a certain pressure. As the B1 clutch engages, the power transmission gradually stabilizes. At this time, the pressure of the C1 piston chamber 30 before the gear shift, that is, the pressure in the sixth gear, is restored. The C2 piston chamber 31 is completely depressurized, and the C2 piston 2 returns to the free position under the action of the C2 piston return spring 4. The B1 and C1 clutches are fully engaged, the power is output stably, and the transmission shifts from the sixth gear to the fifth gear.

Claims

1. A nested clutch, characterized in that: The invention comprises a clutch outer hub (1) and a clutch piston seat (21) connected to each other, wherein a first cavity is formed between the clutch outer hub (1) and the clutch piston seat (21), wherein a C2 clutch is arranged in the first cavity, wherein the C2 clutch comprises a C2 piston (2), wherein a C1 clutch is arranged on the inner wall of the axial front end of the C2 piston (2), wherein the C1 clutch comprises a C1 piston (12), wherein a balance piston (15) is arranged on the inner wall of the axial rear end of the C2 piston (2); and the axial rear end of the C1 piston (12) passes through the balance piston (15); A turbine shaft (28) is arranged at the center of the clutch piston seat (21); a first thrust bearing (29) is arranged at the axial rear end of the clutch piston seat (21); a C1 clutch outer hub spline sleeve (27) and a C1 clutch outer hub (23) are mounted on the first thrust bearing (29); a second thrust bearing (34) is arranged at the axial rear end of the C1 clutch outer hub spline sleeve (27); a C2 clutch inner hub drive shaft (26) and a C2 clutch inner hub (24) are mounted on the second thrust bearing (34); a third thrust bearing (35) is arranged at the axial rear end of the C2 clutch inner hub drive shaft (26); a clutch output disc spline sleeve (25) and a clutch output disc (9) are mounted on the third thrust bearing (35); A C2 piston return spring (4) is arranged in the annular groove formed by the clutch outer hub (1) and the C2 piston (2), one end of the C2 piston return spring (4) is in contact with the inner wall of the annular groove, and the other end of the C2 piston return spring (4) is provided with a C2 piston back plate (5); A C1 piston return spring (14) is arranged in the annular groove formed by the C2 piston (2) and the C1 piston (12), one end of the C1 piston return spring (14) contacts the inner wall of the annular groove, and the other end contacts the axial front end surface of the balance piston (15); The C2 piston (2) is provided with a plurality of C2 friction plate groups (7); each C2 friction plate group (7) comprises a first C2 friction plate and a second C2 friction plate which are sequentially arranged along the axial direction, the first C2 friction plate being in clearance fit with the clutch outer hub (1); the second C2 friction plate being in clearance fit with the C2 clutch inner hub; The C1 piston (12) is provided with a plurality of C1 friction plate groups (17), and a C1 friction plate back plate (18) is provided at the axial rear end of the C1 friction plate group (17); each C1 friction plate group (17) comprises a first C1 friction plate and a second C1 friction plate sequentially arranged along the axial direction, and the first C1 friction plate is clearance-matched with the clutch outer hub (1); and the second C1 friction plate is clearance-matched with the C2 clutch inner hub; The clutch piston seat (21) is provided with a C2 piston chamber oil inlet passage (32), and the C2 piston chamber oil inlet passage (32) is connected to a C2 piston chamber (30) formed by the clutch outer hub (1), the C2 piston (2) and the clutch piston seat (21) and a pressure source; the clutch piston seat (21) is provided with a C1 piston chamber oil inlet passage (33), and the C1 piston chamber oil inlet passage (33) is connected to a C1 piston chamber (31) formed by the C2 piston (2), the C1 piston (12) and the clutch piston seat (21) and a pressure source.

2. The nested clutch according to claim 1, characterized in that: The outer wall and inner wall of the C2 piston (2) are respectively provided with a C2 piston outer sealing ring (3) and a C2 piston inner sealing ring (11); the outer wall and inner wall of the C1 piston (12) are respectively provided with a C1 piston outer sealing ring (13) and a C1 piston inner sealing ring (20); and the outer wall of the balancing piston (15) is provided with a balancing piston sealing ring (22).

3. The nested clutch according to claim 1, characterized in that: A C2 piston back plate elastic retaining ring (6) is arranged on the inner wall of the clutch outer hub (1) at the axial rear end of the C2 piston back plate (5).

4. The nested clutch according to claim 1, characterized in that: A balancing piston elastic retaining ring (16) is arranged on the inner wall of the clutch piston seat (21) at the axial rear end of the balancing piston (15).

5. The nested clutch according to claim 1, characterized in that: A clutch output disc elastic retaining ring (10) is arranged on the inner wall of the clutch outer hub (1) at the axial rear end of the clutch output disc (9).

6. The nested clutch according to claim 1, characterized in that: A C2 friction plate group elastic retaining ring (8) is arranged on the inner wall of the clutch outer hub (1) at the axial rear end of the plurality of C2 friction plate groups (7).

7. The nested clutch according to claim 1, characterized in that: A C1 friction plate back plate elastic retaining ring (19) is arranged on the inner wall of the clutch piston seat (21) at the axial rear end of the C1 friction plate back plate (18).

8. The nested clutch according to claim 1, characterized in that: The balancing piston (15) is provided with a plurality of rectangular holes evenly distributed in the circumferential direction, and the axial rear end of the C2 piston (2) is arranged in the rectangular hole.

9. A gear shift control method, characterized in that: Based on the nested clutch and B1 clutch according to any one of claims 1 to 8, the method specifically comprises the following steps: Step 1: When the C2 piston chamber (30) and the C1 piston chamber (31) reach their respective given working pressures, the C1 clutch and the C2 clutch are both engaged, and the hydraulic automatic transmission forms a middle gear; Step 2: The transmission control unit sends a shift signal, and each clutch is separated or engaged according to the shift logic table; If the shift signal is to switch to a higher gear, the C1 clutch is disengaged and the B1 clutch is engaged; if the shift signal is to switch to a lower gear, the C2 clutch is disengaged and the B1 clutch is engaged.

10. The shift control method according to claim 9, characterized in that: The C1 clutch disengagement and B1 clutch engagement specifically include the following steps: S1, gradually reducing the pressure of the C1 piston chamber (31), so that the pressing force of the C1 piston (12) gradually decreases, and the torque transmitted by the C1 clutch gradually decreases; at the same time, the B1 clutch starts to fill with oil and reduces the pressure of the C2 piston chamber (30); S2, when the B1 clutch reaches the engagement point pressure, the B1 clutch begins to gradually engage and start to transmit torque, the pressure of the C1 piston chamber (31) decreases to below the engagement point pressure, the C1 clutch no longer transmits torque and maintains a certain pressure; S3, when the B1 clutch is fully engaged and the power transmission gradually stabilizes, the pressure of the C2 piston chamber (30) is restored to the pressure of the intermediate gear; S4, when the C1 piston chamber (31) is completely depressurized, the C1 piston (12) returns to a free position under the action of the C1 piston return spring (14); S5, when the B1 clutch and the C2 clutch are fully engaged, the power is output stably and the gear shift is completed.

11. The shift control method according to claim 9, characterized in that: The C2 clutch disengagement and the B1 clutch engagement specifically include the following steps: P1, gradually increasing the pressure of the C1 piston chamber (31), and then gradually reducing the pressure of the C2 piston chamber (30); P2, the B1 clutch begins to fill with oil. When the B1 clutch reaches the engagement point pressure and gradually engages to start transmitting torque, the pressure in the C2 piston chamber (30) decreases to below the engagement point pressure, and the C2 clutch no longer transmits torque and maintains a certain pressure; P3, when the B1 clutch is fully engaged and the power transmission gradually stabilizes, the pressure of the C1 piston chamber (31) is restored to the pressure of the intermediate gear; P4, when the C2 piston chamber (30) is completely depressurized, the C2 piston (2) returns to a free position under the force of the C2 piston return spring (4); P5, when the B1 clutch and the C1 clutch are fully engaged, the power is output stably and the gear shift is completed.

Images