Sectional type self-adjusting control wet clutch

Abstract

The invention relates to a sectional type self-adjusting control wet clutch, which belongs to the technical field of automatic gearboxes, and comprises a transmission shaft and a clutch piston cylinder, a piston is arranged in a piston cavity of the clutch piston cylinder, the acting surface of the piston is divided into an inner acting surface and an outer acting surface, and a baffle ring is arranged in the clutch piston cylinder. The piston cavity is divided into a first cavity body and a third cavity body by the baffle ring, the first cavity body is communicated with a main oil duct in the transmission shaft, and the inner acting surface and the outer acting surface are respectively positioned in the first cavity body and the third cavity body; a mounting hole extending in the radial direction is further formed in the clutch piston cylinder, a plurality of through holes are formed between the mounting hole and the piston cavity and include a first throttling hole, a second throttling hole, a third throttling hole and a second oil drainage hole, and the clutch piston cylinder is further provided with a first oil drainage hole communicated with the mounting hole. A gear shifting auxiliary control valve is arranged in the mounting hole and comprises a base, a valve piston, a valve rod and a valve sleeve which are sequentially arranged. Auxiliary adjustment of each control stage of the clutch in the gear shifting process can be achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of automatic transmissions, and particularly relates to a wet clutch with segmented self-adjusting control. Background Art

[0002] An AT (automatic transmission) usually includes multiple multi-plate wet shift clutches. For shifting gears, the transmission TCU issues a shift control command after calculating through a shift logic. According to the current gear and the target gear, it drives the proportional solenoid valves corresponding to the clutches to be engaged and disengaged. According to the magnitude of the output control current, the control of the pressure and flow rate of the transmission fluid at the outlet of the proportional solenoid valve can be achieved. After being regulated by the proportional solenoid valve, the transmission fluid enters the piston chamber of the shift clutch through an oil passage. When the thrust generated by the fluid pressure can overcome the resistance of the return spring and the frictional resistance of the clutch piston itself, the fluid pushes the piston to move and gradually presses the friction plates and steel plates, so that the driven part and the driving part of the clutch are engaged to transmit power.

[0003] During the entire process of clutch engagement or disengagement, the magnitudes of its pressure, flow rate, and duration will directly determine the quality of the entire shifting process. Due to some inherent characteristics of the proportional solenoid valve itself (such as the excitation current for initial pressure establishment, hysteresis characteristics, etc.), the control of certain pressure and flow rate segments will be restricted, and it is difficult to achieve precise control of clutch engagement or disengagement during the entire shifting process. Therefore, a large amount of calibration and testing work is required for single control of shifting quality through a proportional solenoid valve. Thus, in the general design process, a constant drain hole is designed on the clutch piston cylinder on the oil inlet side of the shift wet clutch to assist in reducing the pressure impact during the oil filling stage of the clutch during shifting and accelerating the oil drainage process during separation to reduce the separation time. However, the role played by this auxiliary valve is relatively simple and can only play a certain regulating role at a certain stage (such as oil filling or separation), and still cannot achieve the auxiliary effect on the entire control process of the clutch. A large amount of testing work is still required during the shifting debugging and calibration process. Summary of the Invention

[0004] In order to solve the problems of single proportional solenoid valve control and the functional limitations of the constant drain hole solution described above, the present invention provides a wet clutch with segmented self-adjusting control, which uses an auxiliary control valve to achieve the auxiliary adjustment effect on each control stage of the clutch during the shifting process, realizes more precise adjustment control for the entire control process, and greatly reduces the testing and calibration workload of the shifting quality of the automatic transmission.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a wet clutch with segmented self-adjusting control, including a transmission shaft and a clutch piston cylinder. The clutch piston cylinder is fixed on the transmission shaft. A piston is arranged in the piston cavity of the clutch piston cylinder. The acting surface of the piston is divided into an inner acting surface and an outer acting surface in the radial direction and is distributed in a stepped shape. A partition ring is arranged in the clutch piston cylinder. The partition ring divides the piston cavity into a first cavity and a third cavity. The first cavity is communicated with the main oil passage in the transmission shaft. The inner acting surface is located in the first cavity, and the outer acting surface is located in the third cavity; The clutch piston cylinder is also provided with a radially extending mounting hole. The mounting hole is a through hole. A plurality of through holes are arranged on the cylinder wall between the mounting hole and the piston cavity. The plurality of through holes are respectively a first throttle hole, a second throttle hole, a third throttle hole and a second oil drain hole. The cylinder wall of the clutch piston cylinder is also provided with a first oil drain hole that is always communicated with the mounting hole. The first throttle hole is communicated with the first cavity. The second throttle hole, the third throttle hole and the second oil drain hole are all communicated with the third cavity; A shift assist control valve is arranged in the mounting hole, including a base, a valve piston, a valve rod and a valve sleeve arranged in sequence. The base is fixed in the mounting hole, and the base is provided with a through hole. The space between the base and the transmission shaft and the through hole together form a second cavity. The second cavity is always communicated with the first cavity through the first throttle hole; The valve rod slides relatively through the valve sleeve. The proximal end of the valve rod is inserted into the valve piston. The distal end of the valve sleeve is axially positioned in the mounting hole. A valve spring is sleeved outside the valve sleeve. The two ends of the valve spring respectively abut against the valve sleeve and the valve piston; In the initial state of the wet clutch, the valve acting surface of the valve piston forms a seal for the inner hole of the base, the side surface of the valve piston forms a seal for the second throttle hole. The first slot hole arranged on the valve piston is aligned with the third throttle hole. The second slot hole arranged on the valve sleeve is aligned with the second oil drain hole and avoids the valve rod.

[0006] Further, the aperture of the second throttle hole is smaller than the aperture of the first throttle hole. Through the throttling effect of the second throttle hole, the oil pressure in the second cavity can push the valve piston to move and then block the third throttle hole; The aperture of the third throttle hole is larger than the aperture of the second throttle hole.

[0007] Further, the valve piston is a cylindrical structure with one end open. Its closed end is the valve acting surface, and its open end is used to receive the insertion of the valve rod.

[0008] Further, the longitudinal section of the valve rod is in a T shape. Its T-shaped head is inserted into the valve piston through the open end of the valve piston, and the outer diameter of the T-shaped head coincides with the inner diameter of the valve piston. The proximal end of the valve spring abuts against the T-shaped head.

[0009] Further, the longitudinal section of the valve sleeve is T-shaped, with its T-shaped head away from the valve piston and axially fixed in the mounting hole of the clutch piston cylinder by a snap ring. The central hole for accommodating the valve rod in the valve sleeve is a through hole; the distal end of the valve spring abuts against the T-shaped head.

[0010] Further, a gasket is also provided outside the valve sleeve, and the distal end of the valve spring abuts against the gasket.

[0011] Further, fixing holes are provided on the base, and a fixing member passes through the fixing holes to fix the base in the mounting hole.

[0012] Further, an annular groove communicating with the third throttle hole is provided on the inner wall of the mounting hole.

[0013] Further, the engagement process of the wet clutch includes the following three stages: (1) The first stage: Oil enters the first cavity through the main oil passage. One part of the oil acts on the inner acting surface of the piston to form a thrust F1, which pushes the piston to move and eliminates the dead stroke between the piston and the first steel sheet in the clutch piston cylinder; the other part of the oil enters the second cavity through the first throttle hole to form a thrust F2 acting on the valve piston, and F2 is less than the initial elastic force of the valve spring. (2) The second stage: The oil pressure increases, making the thrust F2 greater than the initial elastic force of the valve spring, pushing the valve piston to move. A part of the oil in the second cavity enters the third cavity through the second throttle hole to form a thrust F3 acting on the outer acting surface of the piston; through the action of the second throttle hole, the side surface of the valve piston can completely cover the third throttle hole, and the valve rod moving with the valve piston completely covers the second oil drain hole. (3) The third stage: The oil pressure continues to increase, pushing the valve piston to continue moving, so that the third throttle hole connects the second cavity and the third cavity, and the oil pushes the piston to quickly compress the friction plates and steel sheets of the wet clutch to achieve full engagement.

[0014] Further, the disengagement process of the wet clutch includes the following two stages: (1) The first stage: After the proportional solenoid valve in the wet clutch is de-energized, the oil in the third cavity enters the second cavity through the third throttle hole and the second throttle hole, then enters the first cavity through the first throttle hole, and finally is discharged from the oil drain port of the proportional solenoid valve to the fuel tank through the main oil passage. (2) Second stage: As the oil fluid flows out, the pressures in the third chamber, the second chamber, and the first chamber also decrease. When the thrust F2 in the second chamber is less than the elastic force of the valve spring, the valve spring pushes the valve piston to reset, and at the same time, the valve stem slides along the valve sleeve; when the second oil drain hole is no longer blocked by the valve stem, part of the oil fluid remaining in the third chamber due to the centrifugal force of the clutch rotation will be discharged into the fuel tank through the second oil drain hole, the second slot hole, and the central hole inside the valve sleeve; the remaining oil fluid near the transmission shaft in the third chamber flows into the valve spring gap through the third throttle hole and the first slot hole on the valve piston, and finally is discharged into the fuel tank through the first oil drain hole.

[0015] The beneficial effects of the present invention are as follows: The present invention adopts a multi-component combined shift assist control valve on the wet clutch. This valve can realize the three-stage assist control function during the clutch engagement process, can significantly improve the control effects during the rapid oil filling to eliminate the dead stroke stage, the smooth control during the slip friction control stage, and the rapid engagement stage during the clutch engagement process, and can also improve the oil drainage speed and the rapid discharge effect of the remaining oil fluid during the clutch disengagement process.

[0016] Compared with the clutch control that only adopts a single constant oil drain hole in the prior art, adopting the solution of the present invention can play a better assist control role during the shift process control, shorten the shift time, the shift quality is smooth without impact, the control effect is more accurate, and the control method is simpler. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 It is a schematic structural diagram of the segmented self-adjusting control wet clutch described in the present invention; Figure 2 It is a schematic diagram of the distribution of each oil hole on the clutch piston cylinder in the present invention; Figure 3 It is a schematic diagram of the working principle of the first stage of the shift assist control valve described in the present invention during the wet clutch engagement process; Figure 4 It is a schematic diagram of the working principle of the second stage of the shift assist control valve described in the present invention during the wet clutch engagement process; Figure 5 It is a schematic diagram of the working principle of the third stage of the shift assist control valve described in the present invention during the wet clutch engagement process; Figure 6Schematic diagram of the working principle of the shift assist control valve in the first stage during the separation process of the wet clutch according to the present invention; Figure 7 Schematic diagram of the working principle of the shift assist control valve in the second stage during the separation process of the wet clutch according to the present invention; Figure 8 Schematic diagram of the structure of a wet clutch with a constant drain hole in the prior art; Figure 9 Proportional solenoid valve drive control parameters formed after debugging and calibration for the wet clutch solution with a constant drain hole in the prior art; Figure 10 For the wet clutch solution with a constant drain hole in the prior art and Figure 9 Test curve graph on a real vehicle of the shown control parameters; Figure 11 Proportional solenoid valve drive control parameters formed after debugging and calibration for the wet clutch solution with a shift assist control valve according to the present invention; Figure 12 For the wet clutch solution with a shift assist control valve according to the present invention and Figure 11 Test curve graph on a real vehicle of the shown control parameters; Reference numerals: 1. Clutch piston cylinder, 101. Partition ring, 2. Fixed pin, 3. Base, 4. Valve piston, 401. Valve acting surface, 402. First slot hole, 5. Valve spring, 6. Valve rod, 7. Gasket, 8. Valve sleeve, 801. Central hole, 802. Second slot hole, 9. Snap ring, 10. First throttle hole, 11. Second throttle hole, 12. Third throttle hole, 13. First drain hole, 14. Second drain hole, 15. Piston, 1501. Inner acting surface, 1502. Outer acting surface, 16. Return spring, 17. Friction plate, 18. Steel sheet, 19. Main oil passage, 20. Transmission shaft, 21. First cavity, 22. Second cavity, 23. Third cavity, 24. Clutch outer hub, 25. Clutch inner hub, 26. Gear, 27. Constant drain hole. Detailed implementation manners

[0019] The present invention will be further described in detail below with reference to the drawings and embodiments, but it shall not be used as a basis for any limitation to the invention.

[0020] As Figure 1As shown, a wet clutch with segmented self - regulating control has an overall main structure that is basically the same as that of a conventional wet clutch, including a clutch piston cylinder 1, a piston 15, a return spring 16, friction plates 17, steel plates 18, a transmission shaft 20, a clutch inner hub 25, a clutch outer hub 24, and a gear 26. Only the connection relationships of its main components will be described below. The clutch piston cylinder 1 is fixed on the transmission shaft 20 in an interference - fit manner (or other ways that can achieve a fixed effect). The piston 15 is arranged in the piston cavity of the clutch piston cylinder 1. Both ends of the return spring 16 are abutted against the piston 15 and the clutch inner hub 25 respectively, and are used to control the reset of the piston 15 during the clutch separation stage. The friction plate group composed of the friction plates 17 and the steel plates 18 is arranged inside the clutch hub formed by the clutch inner hub 25 and the clutch outer hub 24. The clutch inner hub 25 is fixed on the transmission shaft 20, and the clutch outer hub 24 is connected to the gear 26.

[0021] When the wet clutch is in the engaged state, the friction plates 17 and the steel plates 18 are pressed by the piston 15. At this time, the power input by the transmission shaft 20 is transmitted to the friction plate group through the clutch inner hub 25, then to the clutch outer hub 24, and finally output through the gear 26.

[0022] The structure of the shift - assist control valve proposed in the present invention, its installation on the wet clutch, and its working principle will be described in detail below.

[0023] Continue to refer to Figure 1As shown, a radially extending mounting hole is provided on one side of the piston chamber of the clutch piston cylinder 1, and the shift assist control valve is installed in the mounting hole, and the length of the shift assist control valve is less than the depth of the mounting hole. The shift assist control valve mainly consists of a base 3, a valve piston 4, a valve spring 5, a valve rod 6, a gasket 7, a valve sleeve 8 and a snap ring 9. The base 3 is designed with fixing holes, and the base 3 is fixed in the mounting hole of the clutch piston cylinder 1 through the fixing holes by a fixing pin 2 or other fixing parts such as screws, and serves as the bottom support of the shift assist control valve. A through hole is provided in the base 3 along its axial direction. The valve piston 4 is provided on the side of the base 3 away from the transmission shaft 20. The valve piston 4 is a cylindrical structure with one end open and one end closed. The closed end is the valve acting surface 401 of the valve piston 4, and corresponds to one end of the through hole in the base 3, so as to block the through hole when the shift assist control valve is in the initial state (at this time, the wet clutch is also in the initial state). The longitudinal section of the valve rod 6 is in a T shape, and its T-shaped head is inserted into the valve piston 4 through the open end of the valve piston 4, and the outer diameter of the T-shaped head matches the inner diameter of the valve piston 4; the rod body part of the valve rod 6 is inserted into the central hole of the valve sleeve 8 and is slidably matched with the valve sleeve 8. The longitudinal section of the valve sleeve 8 is in a T shape, and its T-shaped head is away from the valve piston 4 and is axially fixed in the mounting hole of the clutch piston cylinder 1 by a snap ring 9. The central hole in the valve sleeve 8 is a through hole. A valve spring 5 and a gasket 7 are also sleeved outside the valve sleeve 8. The proximal end of the valve spring 5 contacts the valve piston 4, and the distal end contacts the gasket 7. The gasket 7 is used to adjust the initial elastic force of the valve spring 5 in the initial state. Increasing the number of gaskets 7 will increase the initial elastic force, and vice versa will decrease the initial elastic force.

[0024] It should be noted that in the present invention, the "proximal end" and "distal end" are both referenced to the transmission shaft 20. The one close to the transmission shaft 20 is the "proximal end", and the one far from the transmission shaft 20 is the "distal end".

[0025] As Figure 2As shown, the acting surface of the piston 15 is radially divided into two inner acting surfaces 1501 and outer acting surfaces 1502 with a certain axial spacing. Therefore, the inner acting surface 1501 and the outer acting surface 1502 form a stepped surface. The inner acting surface 1501 is close to the transmission shaft 20, and the outer acting surface 1502 is far from the transmission shaft 20. One side of the clutch piston cylinder 1 facing the piston 15 is provided with a ring of partition rings 101. The partition rings 101 extend along the axial direction of the transmission shaft 20 in the piston cavity, dividing the piston cavity into two parts radially. The cavity close to the transmission shaft 20 is the first cavity 21, and the cavity far from the transmission shaft 20 is the third cavity 23. Among the two acting surfaces of the piston 15, the acting surface in the first cavity 21 is the annular inner acting surface 1501, and the acting surface in the third cavity 23 is the annular outer acting surface 1502. A main oil passage 19 is arranged inside the transmission shaft 20 of the wet clutch. One end of the main oil passage 19 opens on the circumferential surface of the transmission shaft 20 and is in communication with the first cavity 21. The space between the base 3 and the axial surface of the transmission shaft 20 and the pore channels inside the base 3 together form the second cavity 22. The second cavity 22 and the first cavity 21 are in communication through a first throttle hole 10 provided on the clutch piston cylinder 1. One side cylinder wall of the clutch piston cylinder 1 facing the piston 15 is further provided with a second throttle hole 11, a third throttle hole 12 and a second oil drain hole 14. One side of the clutch piston cylinder 1 facing away from the piston 15 is provided with a first oil drain hole 13. The second throttle hole 11, the third throttle hole 12 and the second oil drain hole 14 are separated from the first throttle hole 10 by the partition ring 101. Therefore, the second throttle hole 11, the third throttle hole 12 and the second oil drain hole 14 are all in communication with the third cavity 23.

[0026] The inner ends of the second throttle hole 11 and the second oil drain hole 14 both open on the wall of the installation hole inside the clutch piston cylinder 1, and the outer ends open and are in communication with the third cavity 23. The inner end of the third throttle hole 12 opens on the wall of the installation hole of the clutch piston cylinder 1, and the outer end opens and is in communication with the third cavity 23.

[0027] When the wet clutch is in the initial state, the shift assist control valve is also in the initial state. At this time, the valve acting surface 401 at one end of the valve piston 4 fits against the end surface of the base 3 to block the second cavity 22. At the same time, a position on the side of the valve piston 4 close to the base 3 can form a blockage of the second throttle hole 11. And a first slot hole 402 is further provided on the side of the valve piston 4, which is aligned and in communication with the third throttle hole 12. The T-shaped head of the valve sleeve 8 is provided with a second slot hole 802 that radially penetrates the valve sleeve 8 and is aligned and in communication with the second oil drain hole 14 in the initial state. And the inner side of the second slot hole 802 is in communication with the central hole 801 inside the valve sleeve 8. The first oil drain hole 13 is in communication with the space where the valve spring 5 is located outside the valve sleeve 8.

[0028] Preferably, a circumferentially extending annular groove is provided on the hole wall of the mounting hole at the inner end opening of the third flow hole 12, and the third flow hole 12 communicates with the first slot hole 402 on the side surface of the valve piston 4 through the annular groove.

[0029] Preferably, an annular groove is provided on the outer circular surface of the valve sleeve 8, and the second oil drain hole 14 communicates with the second slot hole 802 through the annular groove.

[0030] A plurality of piston seals are provided between the piston 15, the clutch piston cylinder 1 and the transmission shaft 20. The piston seals can be sealing rings, and the piston seals can be provided on the piston 15, the clutch piston cylinder 1 or the transmission shaft 20, which can be specifically determined according to design requirements.

[0031] Figure 1 、 2 The figure shows the initial state of the wet clutch. The control process of the wet clutch is divided into two types: engagement and disengagement control. Therefore, in the following content, the control principle of the shift assist control valve during the clutch engagement process will be described in combination with Figures 3 - 5 the control principle of the shift assist control valve during the clutch disengagement process will be described in combination with Figures 6 - 7 The orientation words involved, such as "up", "down", "left", "right", etc., are based on the corresponding drawings.

[0032] The engagement process of the wet clutch can be divided into the following three stages: (1) The first stage: As Figure 3 shown, the arrows in the figure indicate the oil flow direction. The oil first enters the first cavity 21 through the main oil passage 19. One way of the oil impacts the inner acting surface 1501 of the piston 15 to form a thrust F1, F1 = P1×S1, where P1 is the oil pressure value in the first stage and S1 is the annular area of the inner acting surface 1501. The value of the formed thrust F1 needs to be greater than the sum of the initial elastic force of the return spring 16 and the piston seal resistance to push the piston 15 to move to the right, thereby eliminating the idle stroke L between the piston 15 and the first steel sheet 18 (as Figure 2 shown). The other way of the oil enters the second cavity 22 through the first throttle hole 10 and impacts the valve acting surface 401 of the valve piston 4 to form a thrust F2, F2 = P2×S2, where P2 is the pressure formed in the second cavity 22 after the oil passes through the first throttle hole 10 (due to the small hole throttling effect of the first throttle hole 10, a pressure difference is formed, so P2 is less than the value of P1), and S2 is the area of the valve acting surface 401. When the value of F2 is less than the initial elastic force of the valve spring 5, the valve piston 4 cannot be pushed to move upward. Otherwise, the valve piston 4 is pushed to move upward.

[0033] The purpose of the first stage is to quickly eliminate the dead stroke L between the piston 15 and the first steel sheet 18. Therefore, the key technical point of the design is to make the oil in the first stage flow into the first cavity 21 at a relatively large flow rate, and control the oil flow rate into the second cavity 22 to avoid the valve piston 4 being lifted up after too much oil enters the second cavity 22, so that the oil enters the third cavity 23 through the second cavity 22 and the second throttle hole 11. Therefore, the value of P1 in this stage needs to ensure that F1 is greater than the sum of the initial elastic force of the return spring 16 and the resistance of the piston seal, and F2 is less than the initial elastic force of the valve spring 5, so as to ensure that the piston 15 can move to the right to eliminate the dead stroke, while the valve piston 4 cannot move upward.

[0034] In this embodiment, the volume of the third cavity 23 is about 3 times that of the first cavity 21. Therefore, according to the volume being equal to the flow rate multiplied by the time, the time for the oil in this embodiment to act on the piston 15 in the first cavity 21 to control and eliminate the dead stroke L is equivalent to about 30% of the time for the oil in the prior art to act on the piston in the piston cavity (i.e., the first cavity 21 and the third cavity 23) to eliminate the dead stroke. Thus, compared with the prior art, the present invention can significantly shorten the control time of this stage. The wet shift clutch structure in the prior art can be referred to Figure 8 as shown, its piston cavity is not divided into two separated cavities and is still an integral cavity.

[0035] (2) The second stage: As Figure 4 shown, the arrow in the figure indicates the oil flow direction. After the first stage is completed, when the value of P1 gradually increases to make F2 greater than the initial elastic force of the valve spring 5, it will push the valve piston 4 to move upward (upward in the figure, actually away from the transmission shaft 20). Then, a part of the oil enters the third cavity 23 through the second throttle hole 11, and the oil impacts the outer working surface 1502 of the piston 15 to form a thrust F3, F3 = P3×S3, where P3 is the pressure formed when the oil enters the third cavity 23 through the second throttle hole 11 (due to the small hole throttling effect of the second throttle hole 11 to form a pressure difference, and the hole diameter is much smaller than that of the first throttle hole 10, so P3 is much smaller than P2 and P1 values), and S3 is the annular area of the outer working surface 1502. The resultant force formed by F1 and F3 acts on the piston 15, where F1 is used to overcome the return spring 16 and the frictional resistance, and F3 is used to continuously push the piston 15 to continue moving to the right, so that the friction plate 17 and the steel sheet 18 are gradually pressed together.

[0036] The purpose of the second stage is to enable the clutch to be in a slip friction state, so that the torque and speed can change smoothly, avoiding engagement shock. Therefore, in this stage, the oil flow rate in the third cavity 23 and the pressure on the external acting surface 1502 need to change gradually and smoothly from small to large. The second throttle orifice 11 plays a key role in throttling and pressure reduction, and its aperture value is the key to the design. Specifically, the aperture design of the second throttle orifice 11 needs to achieve the following purposes: (1) Limit the upper limit of the increase in the P2 pressure in this stage to ensure that the side of the valve piston 4 can completely cover the third throttle orifice 12, preventing oil from entering the third throttle orifice 12; (2) The valve stem 6 moves with the valve piston 4, and the moving amplitude needs to ensure that the position of the valve stem 6 after moving in the valve sleeve 8 can completely cover the second oil drain hole 14, preventing the oil in the third cavity 23 from being discharged to the fuel tank through the second oil drain hole 14.

[0037] (3) The third stage: As Figure 5 shown, the arrow in the figure indicates the oil flow direction. After the second stage is completed, as the P1 value continues to increase, the P2 value also increases. When F2 is greater than the current elastic force of the valve spring 5, it will push the valve piston 4 to move upward continuously, so that the third throttle orifice 12 is no longer blocked by the valve piston 4, connecting the second cavity 22 and the third cavity 23. A part of the oil in the second cavity 22 enters the third cavity 23 through the third throttle orifice 12. Since the aperture of the third throttle orifice 12 is larger than that of the second throttle orifice 11, most of the oil will enter the third cavity 23 through the third throttle orifice 12. Since both the second throttle orifice 11 and the third throttle orifice 12 are connected to the third cavity 23 in this stage, the flow rate and pressure in the third cavity 23 will increase rapidly, so that the clutch friction plate 17 and the steel plate 18 are quickly pressed and finally fully engaged.

[0038] The purpose of the third stage is to enable the clutch to be quickly engaged to form sufficient torque reserve. Therefore, the third throttle orifice 12 plays a key role in increasing the flow rate and raising the pressure in this stage, and its aperture value is the key to the design and needs to be significantly larger than that of the second throttle orifice 11.

[0039] The separation process of the wet shift clutch can be divided into the following two stages: (1) The first stage: As Figure 6 shown, the arrow in the figure indicates the oil flow direction. After the proportional solenoid valve is powered off, its oil drain port opens, and the oil in the clutch oil cavity will flow out from the oil drain port. The oil in the third cavity 23 enters the second cavity 22 through the third throttle orifice 12 and the second throttle orifice 11, then enters the first cavity 21 through the first throttle orifice 10, and then is discharged to the fuel tank from the oil drain port of the proportional solenoid valve through the main oil passage 19.

[0040] (2) The second stage: As Figure 7As shown, the arrow in the figure indicates the oil flow direction. As the oil flows out of the clutch cavity, the pressures in the third cavity 23, the second cavity 22, and the first cavity 21 also decrease. When the thrust F2 in the second cavity 22 is less than the elastic force of the valve spring 5, the valve spring 5 will reset and move the valve piston 4 towards the base 3. At the same time, the valve stem 6 also slides along the valve sleeve 8. When the second oil drain hole 14 is no longer blocked by the valve stem 6, part of the oil remaining in the third cavity 23 due to the centrifugal force of the clutch rotation will be discharged into the fuel tank through the second oil drain hole 14, the second slot 802, and the central hole 801 inside the valve sleeve 8. In addition, part of the remaining oil near the transmission shaft 20 in the third cavity 23 will flow into the gap of the valve spring 5 through the third throttle hole 12 and the first slot 402 on the valve piston 4, and finally be discharged into the fuel tank through the first oil drain hole 13.

[0041] Comparative test: The following is a real vehicle test of the shift control process to compare the control effects of the solution of the present invention with the original solution of the prior art. The evaluation of the effect is mainly based on whether the shift control quality is smooth and the improvement effect of the shift control process (such as shortening the shift time, simplifying the control process, etc.).

[0042] In the original solution of the prior art, a constant oil drain hole 27 communicating with the piston chamber is provided in the clutch piston cylinder 1 of the wet clutch inside the AT automatic transmission, as Figure 8 shown. The solution of the present invention mainly relates to a shift assist control valve, and accordingly, the structure of the clutch piston cylinder 1 is changed, and the other parts have no obvious changes.

[0043] The test AT automatic transmission has a total of 6 forward gears, 6 wet clutches, and 6 proportional solenoid valves. Each gear needs to be formed by the engagement of two clutches. Taking the control process of shifting from the 2nd gear to the 3rd gear as an example, the 2nd gear requires the engagement of the 1st and 5th clutches, and the 3rd gear requires the engagement of the 3rd and 5th clutches. Therefore, the process of shifting from the 2nd gear to the 3rd gear requires the separation of the 1st clutch and the engagement of the 3rd clutch to complete the gear shift. Therefore, the entire shift process needs to control the action (separation) of the 1st proportional solenoid valve corresponding to the 1st clutch and the action (engagement) of the 3rd proportional solenoid valve corresponding to the 3rd clutch. Since the clutch part is a rotating component and it is impossible to install a sensor to collect the actual pressure data in the clutch oil chamber (i.e., the piston chamber, which is the third cavity 23 for the present invention), in actual tests, a pressure sensor is usually installed at the outlet pressure point of the proportional solenoid valve to collect the pressure at the outlet of the solenoid valve, that is, before the main oil passage 19 in the transmission shaft 20 of the clutch. Since there are oil passages and throttle holes between the clutch oil chamber and the outlet of the solenoid valve, according to the hydraulic pressure loss theory, the actual pressure in the clutch oil chamber (i.e., the piston chamber, which is the third cavity 23 for the present invention) is lower than the pressure at the collection point. Since it is impossible to measure it directly, a simulation tool is used to simulate and calculate the pressure in the oil chamber, and a comprehensive analysis is carried out in combination with the actual test results.

[0044] Figure 9 Shown are the proportional solenoid valve drive control parameters formed after debugging and calibration when using the wet clutch solution with a constant drain hole in the prior art. In the figure, the No. 1 clutch to be disengaged maintains a control current of 770 mA from 0 ms to 400 ms and is in the engaged state. At 400 ms, the current directly decreases from 770 mA to 0 mA, indicating that the No. 1 clutch is disengaged at 400 ms. The No. 3 clutch to be engaged maintains a control current of 500 mA from 0 ms to 400 ms and is in the oil filling stage to eliminate the dead stroke. At 400 ms, the current decreases from 500 mA to 330 mA, and then from 400 ms to 1100 ms, the current gradually increases from 330 mA to 420 mA, with a control current change rate of 0.13 mA / ms. This process is used to control the clutch in the slip friction stage to complete torque transmission and speed change. From 1100 ms to 1500 ms, the current rapidly increases from 420 mA to 770 mA, with a control current change rate of 0.875 mA / ms. This process is used to control the clutch to quickly engage to complete torque reserve.

[0045] The wet clutch solution with a constant drain hole and Figure 9 The test results of the control parameters shown on a real vehicle are as Figure 10 shown. In the figure, it is the process of shifting from the second gear to the third gear, and the actual test curve collected according to the Figure 9 shown control parameters. Figure 10 Among the 5 curves in [figure], from the top to the bottom at the leftmost end of the time axis, they respectively represent the engine speed curve, the input speed curve, the output speed curve, the oil pressure curve of the No. 1 clutch, and the oil pressure curve of the No. 3 clutch. And at the severe fluctuation in the middle section of the oil pressure curve of the No. 3 clutch, a simulated oil pressure curve of the No. 3 clutch cavity composed of dots is formed through simulation.

[0046] According to Figure 10As shown in the figure, when the oil filling of the No. 3 clutch in the first stage is completed, the input speed starts to drop from 1155 rpm to 749 rpm, taking 208 ms. Subsequently, there is a speed fluctuation of about 250 ms for the input speed. At the same time, it can also be seen from the figure that there is a slight speed fluctuation in the output speed. This phenomenon results in a slight shift shock in the actual shift quality experience. The pressure at the outlet of the solenoid valve actually collected in the second stage shown in the figure is between 60 - 105 PSI, among which 60 - 95 PSI lasts for about 180 ms and there is a severe fluctuation of about 30 PSI. Through simulation, the theoretical pressure in the clutch oil cavity in this stage is between 80 - 100 PSI, and there is no significant drop compared with the collected pressure. The reason is that during the oil filling process in the first stage, when the piston moves to the right, the entire cavity of the clutch is fully opened. After eliminating the dead stroke and entering the second stage, the entire cavity is already filled with oil, and the oil pressure in the cavity is close to the oil pressure in the oil inlet passage. Through actual measurement and verification, the method to eliminate the shift shock is to adjust the initial oil pressure in the second stage, i.e., the slip friction stage. However, the minimum excitation current for the proportional solenoid valve to establish the oil pressure is 300 - 320 mA, Figure 7 At the beginning of the slip friction stage in the figure, the control current of the No. 3 clutch decreases from 500 mA to 330 mA. 330 mA is slightly greater than the excitation current for the proportional solenoid valve to establish the pressure. Actual verification shows that if it is further decreased, there will be a phenomenon that the oil pressure starts to oscillate violently at the end of the oil filling, and the input speed starts to rise rapidly instead of dropping. This phenomenon is the power interruption phenomenon. Analyzing the root cause, on the one hand, it is because there is a lower limit restriction on the excitation current for the proportional solenoid valve to establish the oil pressure, and on the other hand, the constant drain hole is continuously draining oil, and the flow rate in the clutch oil cavity cannot be maintained in a stable state, resulting in violent fluctuations in the oil pressure. At the same time, it is verified in the test that if the oil filling time in the first stage is increased, the shift shock is more obvious (causing a significant increase in the oil pressure in the clutch oil cavity), and if the oil filling time is reduced, there will be a short power interruption phenomenon at the end of the oil filling. Therefore, the figure shows the acceptable control state after final debugging and calibration, and there is a slight shift shock in the shift quality. In addition, as shown in the figure, the separation of the No. 1 clutch starts at 343.6 s, drops to 20 PSI at 343.7 s and then maintains for about 190 ms, and drops to 0 PSI at 343.9 s, taking a total of 300 ms. The section of the oil pressure maintained at 20 PSI indicates that the residual oil in the clutch oil cavity is not discharged quickly.

[0047] Figure 11The figure shows the proportional solenoid valve drive control parameters formed after debugging and calibration when the wet clutch solution with a shift assist control valve of the present invention is adopted. The No. 1 clutch to be disengaged maintains a control current of 770 mA and is in the engaged state from 0 ms to 200 ms. At 200 ms, the current directly decreases from 770 mA to 0 mA, indicating that the No. 1 clutch is controlled to disengage at 200 ms. The No. 3 clutch to be engaged maintains a control current of 500 mA and is in the oil filling stage from 0 ms to 150 ms to eliminate the dead stroke. From 150 ms to 500 ms, the current gradually increases from 500 mA to 570 mA, and the control current change rate is 0.2 mA / ms. This process is used to control the clutch to be in the slip friction stage to complete torque transfer and speed change. From 650 ms to 1000 ms, the current rapidly increases from 570 mA to 770 mA, and the control current change rate is 0.57 mA / ms. This process is used to control the clutch to quickly engage to complete torque reserve.

[0048] The test results of the wet clutch solution with a shift assist control valve and Figure 11 the control parameters shown on a production vehicle are as Figure 12 shown.

[0049] Figure 12 The figure shows the process of shifting from the second gear to the third gear, and the actual test curve collected according to the Figure 11 control parameters shown. Figure 12 Among them, the five curves from top to bottom at the leftmost end of the time axis respectively represent the engine speed curve, the input speed curve, the output speed curve, the oil pressure curve of the No. 1 clutch, and the oil pressure curve of the No. 3 clutch. And in the middle section of the oil pressure curve of the No. 3 clutch, a simulated oil pressure curve composed of dots in the cavity of the No. 3 clutch is formed through simulation.

[0050] Figure 12As shown, there are no fluctuations in the input speed and output speed during the second slip friction stage, and the actual test shows smooth gear shifting without any impact. By comparing the pressure collected at the outlet of the solenoid valve of the No. 3 clutch in the figure with the pressure in the oil chamber obtained by simulation, it can be seen that the actual oil filling time of this scheme is about 170 ms. When entering the second stage after completing the first stage, the simulated oil pressure rapidly rises from 0 PSI to 60 PSI, and then gradually rises to 85 PSI. During this process, torque transmission and speed change are completed. According to the working principle of the shift assist valve scheme described above, since no oil enters the third chamber 23 during the first stage, the oil pressure is 0 PSI. After entering the second stage, the oil enters the third chamber 23 through the second throttle hole 11, and the second throttle hole 11 produces a significant small hole throttling effect, so that the oil pressure in the third chamber 23 is significantly lower than the oil pressure at the outlet of the solenoid valve. Moreover, due to the throttling effect, the flow rate entering the third chamber 23 is controlled, so that the oil pressure during the slip friction stage can be kept low and change smoothly, ensuring the smoothness of the gear shifting process. In addition, the separation of the No. 1 clutch shown in the figure starts at 1692 s and drops to 0 PSI at 1692.15 s, taking a total of 150 ms, and there is no phenomenon of residual oil maintaining a low oil pressure for a certain period of time as described in the previous case, indicating that the oil can be quickly discharged when the clutch is separated in this scheme and the separation time is shortened.

[0051] According to the comparison of the above actual shift test results, compared with the clutch scheme with a constant drain hole, when using the shift assist control valve clutch scheme of the present invention during gear shifting, the oil filling time to eliminate the dead stroke in the first stage is shortened from 400 ms to 170 ms; during the second stage of slip friction, the oil pressure in the third chamber 23 of the clutch can be controlled between 60 - 85 PSI. Compared with the 80 - 100 PSI in the cavity of the scheme with a constant drain hole, it drops by 15 - 20 PSI, and it is not limited by the lower limit value of the excitation current of the proportional solenoid valve. The entire gear shifting process time is reduced from 1500 ms in the original scheme to 1000 ms. After a large number of debug calibrations, there is still slight gear shifting jerks in the clutch scheme with a constant drain hole. The scheme of the present invention has smooth gear shifting without impact and simple control parameters.

[0052] Overall effect evaluation: After adopting the scheme of the present invention, the gear shifting is smooth without impact, and the oil filling stage and separation stage times are significantly shortened during the gear shifting process, thus shortening the entire gear shifting time. Compared with the original scheme with a constant drain hole that relies on controlling the engagement process by the magnitude of the output current of the proportional solenoid valve, in the control process of the scheme of the present invention, due to the segmented automatic adjustment of the shift assist valve, the dependence on the current output control of the proportional solenoid valve is greatly reduced. Instead, the adjustable range and effect of the solenoid valve are further expanded, and the difficulty of debugging and calibrating the gear shifting quality is reduced.

[0053] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Those of ordinary skill in the art should understand that the specific implementation manners of the present invention can be modified or equivalently replaced by referring to the above embodiments. Any such modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are within the scope of protection of the claims pending for approval.

Claims

1. A segmented self-adjusting wet clutch, comprising a transmission shaft and a clutch piston cylinder, wherein the clutch piston cylinder is fixed on the transmission shaft, a piston is arranged in a piston cavity of the clutch piston cylinder, and the working surface of the piston is divided into an inner working surface and an outer working surface in a radial direction and is distributed in a step shape, characterized in that: A baffle ring is arranged in the clutch piston cylinder, and the baffle ring divides the piston cavity into a first cavity and a third cavity. The first cavity is connected with the main oil passage in the transmission shaft, the inner action surface is located in the first cavity, and the outer action surface is located in the third cavity. A radially extending mounting hole is also provided in the clutch piston cylinder, the mounting hole is a through hole, a plurality of through holes are provided on the cylinder wall between the mounting hole and the piston cavity, the plurality of through holes are respectively a first throttle hole, a second throttle hole, a third throttle hole and a second oil drain hole, a first oil drain hole which is always connected to the mounting hole is also provided on the cylinder wall of the clutch piston cylinder, the first throttle hole is connected to the first cavity, and the second throttle hole, the third throttle hole and the second oil drain hole are all connected to the third cavity; The mounting hole is provided with a shift auxiliary control valve, including a base, a valve piston, a valve stem and a valve sleeve which are arranged in sequence. The base is fixed in the mounting hole, and the base is provided with a through hole. The space between the base and the transmission shaft and the hole together form a second cavity, and the second cavity is always connected to the first cavity through the first throttle hole. The valve stem is relatively slidably inserted into the valve sleeve, the proximal end of the valve stem is inserted into the valve piston, and the distal end of the valve sleeve is axially positioned in the mounting hole. A valve spring is arranged outside the valve sleeve, and the two ends of the valve spring are respectively pressed against the valve sleeve and the valve piston. In the initial state of the wet clutch, the valve acting surface of the valve piston forms a blockage on the channel in the base, the side surface of the valve piston forms a blockage on the second throttling hole, the first slot hole set on the valve piston is aligned with the third throttling hole, and the second slot hole set on the valve sleeve is aligned with the second oil drain hole and avoids the valve stem.

2. The segmented self-adjusting controlled wet clutch according to claim 1 is characterized in that: The aperture of the second throttling hole is smaller than that of the first throttling hole, and through the throttling effect of the second throttling hole, the oil pressure in the second cavity pushes the valve piston to move and can block the third throttling hole; the aperture of the third throttling hole is larger than that of the second throttling hole.

3. The segmented self-adjusting controlled wet clutch according to claim 1 is characterized in that: The valve piston is a columnar structure with one end open, the closed end of which is the valve action surface, and the open end is used to receive the insertion of the valve stem.

4. The segmented self-adjusting controlled wet clutch according to claim 3 is characterized in that: The longitudinal section of the valve stem is T-shaped, and its T-shaped head is inserted into the valve piston through the open end of the valve piston, and the outer diameter of the T-shaped head matches the inner diameter of the valve piston, and the proximal end of the valve spring is pressed against the T-shaped head.

5. The segmented self-adjusting controlled wet clutch according to claim 1 is characterized in that: The longitudinal section of the valve sleeve is T-shaped, and its T-shaped head is away from the valve piston and is axially fixed in the mounting hole of the clutch piston cylinder by a retaining ring. The central hole of the valve sleeve that accommodates the valve stem is a through hole; the distal end of the valve spring is pressed against the T-shaped head.

6. The segmented self-adjusting controlled wet clutch according to claim 5 is characterized in that: A gasket is also arranged outside the valve sleeve, and the distal end of the valve spring presses against the gasket.

7. The segmented self-adjusting controlled wet clutch according to claim 1, characterized in that: The base is provided with a fixing hole, and the fixing piece passes through the fixing hole to fix the base in the installation hole.

8. The segmented self-adjusting controlled wet clutch according to claim 1, characterized in that: An annular groove communicating with the third throttle hole is arranged on the inner wall of the mounting hole.

9. The segmented self-adjusting controlled wet clutch according to any one of claims 1 to 8, characterized in that: The engagement process of a wet clutch consists of the following three stages: (1) First stage: The oil enters the first cavity through the main oil channel. One path of the oil acts on the inner surface of the piston, forming a thrust F1, pushing the piston to move and eliminating the idle stroke between the piston and the first steel plate in the clutch piston cylinder; the other path of the oil enters the second cavity through the first throttle hole, forming a thrust F2 acting on the valve piston, and F2 is smaller than the initial elastic force of the valve spring; (2) Second stage: The oil pressure increases, making the thrust F2 greater than the initial elastic force of the valve spring, pushing the valve piston to move. A portion of the oil in the second chamber enters the third chamber through the second throttling hole, acting on the outer surface of the piston to form a thrust F3. Through the action of the second throttling hole, the side of the valve piston can completely cover the third throttling hole, and the valve stem moving with the valve piston completely covers the second oil drain hole. (3) The third stage: The oil pressure continues to increase, pushing the valve piston to continue moving, so that the third throttle hole connects the second cavity and the third cavity. The oil pushes the piston to quickly press the friction plate and steel plate of the wet clutch to achieve complete engagement.

10. The segmented self-adjusting controlled wet clutch according to any one of claims 1 to 8, characterized in that: The disengagement process of the wet clutch includes the following two stages: (1) The first stage: After the proportional solenoid valve in the wet clutch is powered off, the oil in the third chamber enters the second chamber through the third throttle hole and the second throttle hole, then enters the first chamber through the first throttle hole, and finally is discharged into the oil tank from the oil drain port of the proportional solenoid valve through the main oil channel; (2) The second stage: As the oil flows out, the pressure in the third cavity, the second cavity and the first cavity also decreases. When the thrust F2 in the second cavity is less than the elastic force of the valve spring, the valve spring pushes the valve piston to reset, and the valve stem slides along the valve sleeve; when the second oil drain hole is no longer blocked by the valve stem, part of the oil remaining in the third cavity due to the centrifugal force of the clutch rotation will be discharged into the oil tank through the second oil drain hole, the second slot hole and the center hole inside the valve sleeve; part of the residual oil in the third cavity close to the transmission shaft flows into the valve spring gap through the third throttle hole and the first slot hole on the valve piston, and is finally discharged into the oil tank through the first oil drain hole.

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