CN112576640B - A clutch and a method for finding a half-engagement point of the clutch - Google Patents

Abstract

The invention relates to the technical field of automobile clutch control, and discloses a clutch and a method for finding a half joint point of the clutch. The clutch includes an outer hub, a main hub, a friction plate set, a piston, and a balance piston; A return spring set is provided, and an elastic member is provided on the path where the piston pushes the friction plate set to move axially. The method for finding the half-engagement point of the clutch includes the steps of: filling the pressure chamber with oil; detecting and recording the pressure of the pressure chamber and the displacement of the piston in real time; drawing and forming the spring stiffness curve; reading the pressure point corresponding to the inflection point formed by the change of the spring stiffness , it is judged that this pressure point is a semi-joint point. It can make the search for the half-engagement point more accurate and intuitive, which is beneficial to improve the control accuracy of the clutch and the smoothness of gear shifting. At the same time, it can reduce the difficulty of finding the KP point, improve the test efficiency, and thereby reduce the cost.

Description

A clutch and a method for finding a half-engagement point of the clutch

technical field

The invention relates to the technical field of automobile clutch control, in particular to a clutch and a method for finding a half-engagement point of the clutch.

Background technique

At present, automatic transmissions are widely used, among which hydraulic electronically controlled automatic transmissions (abbreviated as AT) and dual-clutch automatic transmissions (abbreviated as DCT) account for a relatively large proportion. The wet clutch is an important actuator for gear shifting. The control accuracy of the wet clutch directly affects the quality of the gear shifting process, and has an impact on improving efficiency and reducing fuel consumption. A wet clutch is generally composed of a friction plate set, a piston that pushes and compresses the friction plate set, and a return spring. Through precise control of the pressure of the wet clutch, continuous shifting operations without interruption of power can be realized. The precise control of the wet clutch depends on accurately confirming the half engagement point (KP point for short). The half engagement point is actually the pressure point at which the theoretical torque transmission capacity is 0 when the piston of the clutch and the friction disc set are just in contact under the action of the oil pressure and the return spring.

Due to the difficulty in finding the half-engagement point, in the prior art, the corresponding relationship between the ability of the clutch to transmit torque and the pressure is often used to artificially define the pressure corresponding to a state of low transmission torque as the half-engagement point. At present, the following two methods are mainly used to find the semi-junction point:

1. Consider the KP point by measuring the pressure point corresponding to the corresponding torque transmitted by the wet clutch. The specific steps are: 1) Confirm the drag torque of the wet clutch itself under specific working conditions, such as constant clutch input speed 1000rpm, clutch output fixed Do not move, given a cooling flow rate of 1Lpm, read the drag torque of the clutch itself through the torque sensor; 2) On the basis of the measured drag torque, artificially add a certain value of torque, it is considered that the clutch corresponds to the state of transmitting the corresponding torque The pressure is the KP point pressure. If the measured drag torque of a wet clutch is 5nm, it can be considered that the corresponding pressure of the clutch under the state of transmitting 10nm torque is the KP point pressure. On the one hand, this method ignores the tendency of the drag torque to gradually increase as the piston stroke decreases. On the other hand, since the output torque of the clutch is not constant, there will be certain torque fluctuations, and there are differences in how to determine that the judgment value is reached.

2. Calculating the semi-engagement point through the pressure and torque curves, the specific steps are: 1) Measure the torque pressure curve of the wet clutch by adjusting the pressure. For example, the rotation speed of the clutch input end is 1000rpm, the output end of the clutch is fixed, and the cooling flow rate of 1Lpm is given to control the oil pressure from 0 to the maximum pressure that the clutch can withstand. Draw the pressure-torque curve of this process; 2), by processing the curve, such as selecting the pressure 50% to 75% section curve (as shown in Figure 1), do the reverse extension line and the pressure coordinate axis intersect at one point according to the slope, Think of this point as the KP point. This method attempts to remove the influence of drag torque by analyzing the torque-pressure curve, but this method is too theoretical and ignores the nonlinear stiffness change trend of the compression element during the elastic deformation stage.

Existing solutions rely on the measurement of the correlation between the wet clutch transmission torque and pressure, and cannot remove the influence of drag torque. However, the drag torque of the wet clutch itself changes with the external environment. For example, the greater the cooling flow, the greater the drag torque; the smaller the piston stroke. The greater the drag torque, etc. And considering that the tolerance accumulation of individual clutches will affect the magnitude of the drag torque, the selection accuracy of the KP point is limited.

Therefore, how to simplify the finding of the half-junction and improve its accuracy is an important technical problem to be solved by those skilled in the art.

Contents of the invention

The purpose of the present invention is to provide a clutch and a method for finding the half-engagement point of the clutch, which can make the search for the half-engagement point more accurate and intuitive, which is conducive to improving the control accuracy of the clutch, improving the smoothness of shifting, and reducing the KP point at the same time Find the difficulty, improve testing efficiency, thereby reducing costs.

In order to achieve the above object, one aspect of the present invention provides a clutch, which includes an outer hub, a main hub, a friction disc set connected in the outer hub, axially slidably connected to the main hub for compression Or loosen the piston of the friction plate group and the balance piston connected to the main hub, the balance piston, the main hub and the piston form a balance cavity, and a gap is formed between the piston and the main hub. pressure chamber;

A return spring set is provided between the balance piston and the piston for the piston to abut and compress when moving axially toward the friction plate set, and when the piston pushes the friction plate set to move axially Elastic parts are provided on the path.

As a preferred solution, the elastic member is connected to the outer hub and arranged on a side of the friction plate group close to the piston.

As a preferred solution, the elastic member is connected to a side of the piston facing the friction plate set.

As a preferred solution, the friction plate set includes a disc-shaped friction plate and a steel plate arranged at intervals in sequence, and the elastic member is arranged between the friction plate and the steel plate.

As a preferred solution, the side of the friction plate set away from the piston is provided with a first clamping spring for axial limitation, and the elastic member is arranged between the first clamping spring and the friction plate set.

As a preferred solution, the return spring group is pre-compressed and arranged between the balance piston and the piston; the elastic member is a radially arranged ripple spring.

As a preferred solution, the clutch further includes a displacement detection device for detecting the axial displacement of the piston, and a pressure detection device for detecting the oil pressure of the pressure chamber.

As a preferred solution, the displacement detection device adopts a displacement sensor, and the pressure detection device adopts a pressure sensor; the main hub is provided with a first oil passage communicated with the pressure chamber and a second oil passage communicated with the balance chamber. An oil passage; the displacement sensor is connected to the piston, and the pressure sensor is arranged in the first oil passage.

Another aspect of the present invention also provides a method for finding a clutch half-engagement point, comprising the steps of:

Fill the pressure chamber with oil;

Detect and record the pressure of the pressure chamber and the displacement of the piston in real time;

According to the records of oil pressure and displacement, draw the curve of displacement changing with pressure to form the spring stiffness curve;

Read the pressure point corresponding to the inflection point formed by the change of spring stiffness, and determine that this pressure point is a half joint point.

Another aspect of the present invention also provides a method for finding a clutch half-engagement point, which is characterized in that it includes the following steps:

Judging whether the conditions for entering the semi-joint point self-learning are met: obtain the idle time of the vehicle, and compare the idle time with the preset time t1;

If the idle time is greater than the preset time t1, it will enter the semi-junction point self-learning;

If the idle time is less than or equal to the preset time t1, the condition for entering the semi-junction self-learning is not satisfied, and returns to the step of judging whether the condition for entering the semi-joint self-learning is satisfied;

Described semi-junction self-learning comprises the steps:

Fill the pressure chamber with oil;

Detect and record the pressure of the pressure chamber and the displacement of the piston in real time;

According to the records of oil pressure and displacement, draw the curve of displacement changing with pressure to form the spring stiffness curve;

Read the pressure point corresponding to the inflection point formed by the spring stiffness change, and determine that the pressure point is a half joint point;

Record the information of the determined half-joint point to the vehicle CPU in real time, and at the same time overwrite the last record of the half-joint point in the vehicle CPU.

Compared with the prior art, the beneficial effects of the present invention are:

The clutch of the present invention comprises an outer hub, a main hub, a friction disc set connected in the outer hub, a piston that can be axially slidably connected to the main hub to compress or loosen the friction disc set, a balance piston connected to the main hub, A pressure chamber is formed between the piston and the main hub, and a return spring set is provided between the balance piston and the piston for the piston to abut and compress when moving axially toward the friction plate set, and the path where the piston pushes the friction plate set to move axially There is an elastic piece on the top, after the hydraulic oil is supplied to the pressure chamber, the piston overcomes the elastic force of the return spring and moves axially towards the friction plate group under the action of the oil pressure. During this process, the axial direction of the piston is detected respectively. Displacement and the size of the oil pressure in the pressure chamber, and draw the curve of the piston displacement with the oil pressure of the pressure chamber according to the test results to form a spring stiffness curve. contact or indirect contact through the elastic member), the elastic member on the path where the piston pushes the friction plate group to move axially will be squeezed, and the elastic member will start to produce a reverse force, superimposed with the stiffness of the return spring, and at the same time exerting pressure on the piston The axial movement of the piston forms an obstacle, causing the slope of the spring stiffness curve acting on the piston to change immediately, so that an inflection point appears, and the pressure point corresponding to the inflection point can be judged as the KP point. For the detection of the axial displacement of the piston and the detection of the oil pressure in the pressure chamber, in the off-line test, the tester can use the displacement detection tool and the pressure detection tool to detect it respectively; The arrangement of the pressure sensor is used to realize the detection. The structure of this clutch is simple, and the body of the wet clutch is optimized. The method of finding the KP point of the clutch is simple and easy. It only needs to provide oil pressure to the clutch. The KP point found is more intuitive and accurate, and the interference factors are eliminated. Finding the influence of the KP point, so as to improve the control accuracy of the wet clutch, is conducive to improving the smoothness of shifting, improving efficiency, reducing fuel consumption, and is conducive to improving test efficiency and reducing costs.

Description of drawings

Fig. 1 is the schematic diagram of calculating the semi-joint point through pressure and torque curves in the prior art;

Fig. 2 is a schematic structural diagram of a clutch provided in Embodiment 1 of the present invention;

Fig. 3 is a schematic structural diagram of a clutch provided in Embodiment 2 of the present invention;

Fig. 4 is a schematic diagram of a method for finding the half-engagement point of the clutch in Embodiment 1 provided by the present invention;

Fig. 5 is a schematic diagram of calculating the semi-joint point according to the pressure and displacement curve provided by the embodiment of the present invention;

Fig. 6 is a schematic diagram of the method for finding the half-engagement point of the clutch in the second embodiment provided by the present invention.

Among them, 10, outer hub; 11, first circlip; 20, main wheel hub; 21, second circlip; 22, first oil passage; 23, second oil passage; 30, friction plate group; 31, friction plate ; 32, steel sheet; 40, piston; 41, pressure chamber; 42, balance chamber; 43, first seal ring; 44, second seal ring; 50, balance piston; 60, displacement detection device; 70, pressure detection device ; 80, return spring group; 90, elastic member.

Detailed ways

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", " The orientations or positional relationships indicated by "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying Describes, but does not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and operate in a specific orientation, and therefore should not be construed as limiting the invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and should not be understood as indicating or implying relative importance.

Embodiment one:

Please refer to FIG. 2 , which schematically shows a clutch of the present invention, which includes an outer hub 10 , a main hub 20 , a friction plate set 30 , a piston 40 and a balance piston 50 . Wherein, the friction plate set 30 is connected in the outer hub 10, the piston 40 is axially slidably connected to the main hub 20 to compress or loosen the friction plate set 30, and the balance piston 50 Connected to the main hub 20, a first sealing ring 43 and a second sealing ring 44 are provided between the piston 40 and the main hub 20, so that the piston 40 and the main hub 20 are interference-sealed, A pressure chamber 41 is formed between the piston 40 and the main hub 20, the balance piston 50, the main hub 20 and the piston 40 enclose a balance chamber 42, the balance piston 50 and the piston 40 A return spring set 80 is provided therebetween, and the piston 40 can abut against and compress the return spring set 80 when moving axially toward the friction plate set 30 . What is important is that an elastic member 90 is provided on the path where the piston 40 pushes the friction plate set 30 to move axially, so that the piston 40 will directly or indirectly squeeze the friction plate group 30 during the axial movement. The elastic member 90 , so that the elastic member 90 generates a force that hinders the axial movement of the piston 40 toward the friction plate set 30 .

Specifically, in this embodiment, the balance piston 50 is made of steel, and the connection between the balance piston 50 and the piston 40 is vulcanized to attach rubber to achieve an interference fit as a seal. The balance piston 50 is provided with a second clip spring 21 between the balance piston 50 and the main hub 20, and the balance piston 50 is axially positioned through the second clip spring 21, and the balance piston 50 is connected to the main hub 20 through the second clip spring 21. Interference fit acts as a seal. It can be understood that the second snap ring 21 , the first sealing ring 43 and the second sealing ring 44 can also be replaced by rubber vulcanization on the balance piston 50 or the surface of the piston 40 as required.

For achieving the same purpose, please refer to Fig. 4, the present invention also provides a kind of method for finding clutch half engagement point, comprises the steps:

S1, filling the pressure chamber 41 with oil;

S2, detect and record the pressure of the pressure chamber 41 and the displacement of the piston 40 in real time;

S3, according to the record of oil pressure and displacement, draw the curve that displacement changes with pressure, form spring stiffness curve;

S4. Read the pressure point corresponding to the inflection point formed by the change of the spring stiffness, and determine that the pressure point is a semi-joint point.

Based on the above technical features of the clutch and the method of finding the half-engagement point of the clutch, in step S1, hydraulic oil is supplied to the pressure chamber 41 to continuously increase the oil pressure, and in step S2, the piston 40 gradually overcomes the return position under the action of the oil pressure The elastic force of the spring moves axially toward the friction plate set 30. At the same time, the tester uses a tool with a displacement detection function and a tool with an oil pressure detection function to detect the axial displacement of the piston 40 and the oil pressure in the pressure chamber 41 respectively in real time. Press the size and record it. In step S3, according to the detected oil pressure and displacement data records, a curve of the displacement of the piston 40 changing with the oil pressure of the pressure chamber 41 is drawn to form a spring stiffness curve (as shown in FIG. 5 ). When the piston 40 continues to move in the axial direction and the piston 40 and the friction plate set 30 just start to contact (direct contact or indirect contact through the elastic member 90), the elastic member 90 located on the path where the piston 40 pushes the friction plate set 30 to move axially Will be squeezed, the elastic member 90 begins to produce a reverse force, superimposed with the stiffness of the return spring, and at the same time hinders the axial movement of the piston 40, causing the slope of the spring stiffness curve acting on the piston 40 to change immediately, Thus, a turning point appears, and in step S4, the pressure point corresponding to the turning point is read, and it can be determined as the KP point. The structure of this clutch is simple, and the body of the wet clutch is optimized. The method of finding the KP point of the clutch is simple and easy. It only needs to provide oil pressure to the clutch. The KP point found is more intuitive and accurate, and the interference factors are eliminated. Find the influence of the KP point (such as drag torque), so as to improve the control accuracy of the wet clutch, which is conducive to improving the smoothness of shifting, improving efficiency, reducing fuel consumption, and is conducive to improving test efficiency and reducing costs.

The clutch of this embodiment and the method for finding the half-engagement point of the clutch are suitable for finding the half-engagement of the clutch before the vehicle is used (such as in the clutch assembly off-line test process, or the gearbox assembly process, or the transmission off-line process). point. The KP point determined in step S4 can be manually recorded in the CPU of the vehicle equipped with the clutch. After the vehicle is put into use, the vehicle CPU will control the clutch based on the KP point information.

Exemplarily, FIG. 2 shows a specific embodiment in which the elastic member 90 is connected to the outer hub 10 and arranged on the side of the friction plate set 30 close to the piston 40 . When the piston 40 continues to move along When the piston 40 moves axially and the friction disc set 30 just starts to contact, the piston 40 starts to contact the elastic member 90. At this time, the resultant elastic force acting on the piston 40 is the stiffness of the elastic member 90 and the return spring The reaction force generated in the case of superimposition makes the spring stiffness curve acting on the piston 40 turn, and the pressure point corresponding to the turning point is determined as the KP point. This method is simple, intuitive and accurate, and solves the problem of determining the KP point. inaccurate defect. In this embodiment, the elastic member 90 is connected to the outer hub 10 through splines.

Exemplarily, the elastic member 90 is connected to the side of the piston 40 facing the friction plate set 30 , and when the piston 40 drives the elastic member 90 to continuously move axially toward the friction plate set 30 , the The elastic member 90 will first contact the friction plate set 30 , and the elastic member 90 will elastically deform when it contacts the friction plate set 30 , that is, an inflection point appears on the spring stiffness curve.

Exemplarily, the friction plate set 30 includes a disc-shaped friction plate 31 and a steel plate 32 arranged at intervals in sequence, and the elastic member 90 is arranged between the friction plate 31 and the steel plate 32, when the piston When 40 moves axially and touches the friction plate set 30, a thrust is generated on the friction plate set 30. Under the action of the thrust, the friction plate 31 and the steel plate 32 will press the elastic member 90, causing elastic deformation of the elastic member 90, thereby making A kink occurs on the spring rate curve. Similarly, the side of the friction plate set 30 away from the piston 40 is provided with a first clamping spring 11 for axially limiting, and the elastic member 90 can also be arranged between the first clamping spring 11 and the first clamping spring 11 . between the above-mentioned friction plate sets 30, when the piston 40 moves axially and touches the friction plate set 30, the thrust received by the friction plate set 30 will be transmitted forward, so that the elastic member 90 is pressed by the friction plate set 30 and the first clamp spring 11 Squeeze and produce elastic deformation, which makes the spring rate curve appear inflection point. It can be seen from this that, in the process of the piston 40 pressing the friction plate set 30, as long as an elastic member 90 is arranged on the moving path of the piston 40 or the friction plate set 30 (an additional elastic member 90 is arranged on the basis of the return spring set 80 ), that is, when the piston 40 just contacts (directly or indirectly through the elastic member 90) the friction plate set 30, the spring stiffness curve acting on the piston 40 changes, so as to quickly find the corresponding pressure point at the inflection point , so as to determine the KP point.

Specifically, the return spring group 80 is pre-compressed and arranged between the balance piston 50 and the piston 40. The return spring group 80 is an element formed by a plurality of small coil springs distributed around the axis. After the cavity 41 is filled with hydraulic oil, the oil pressure will push the piston 40 to produce a tendency to move axially toward the friction plate set 30. Since the return spring is pre-compressed and installed between the balance piston 50 and the piston 40, the oil When the pressure is small, the displacement of the piston 40 is 0. When the pressure of the hydraulic oil increases to be greater than the preload of the return spring, the piston 40 can be pushed to move axially, and the return spring can be further compressed. And when the clutch needs to be disengaged, reduce the oil pressure in the pressure chamber 41 so that the elastic force provided by the return spring is greater than the pressure of the hydraulic oil, and the piston 40 will move away from the friction plate group 30 under the elastic force of the return spring. The direction of the axial movement makes the piston 40 out of contact with the friction plate set 30 . The elastic member 90 adopts a radially arranged corrugated spring, and the surface of the corrugated spring has corrugations and has a certain rigidity. When the piston 40 moves in the axial direction to just contact with the friction disc set 30, the radially arranged corrugated spring is squeezed to produce The elastic deformation generates an elastic force opposite to the moving direction of the piston 40 , so that the curve of the displacement of the piston 40 with the pressure change of the pressure chamber 41 produces an inflection point.

Embodiment two:

Please refer to Figure 3, which schematically shows another clutch of the present invention. The difference between the clutch of this embodiment and Embodiment 1 is that the clutch in this embodiment also includes a sensor for detecting the axial displacement of the piston. A displacement detection device 60, and a pressure detection device 70 for detecting the oil pressure of the pressure chamber.

Please refer to Figure 6, which schematically shows another method for finding the clutch half-engagement point of the present invention, which is applicable to the clutch in the second embodiment, and is different from the method of finding the clutch half-engagement point in the first embodiment. The method, the method for finding the clutch half-engagement point in this embodiment can also be applied to the use of the vehicle. Before the step S1, it also includes a step S0: judging whether the condition for entering the half-engagement point self-learning is met: obtaining the vehicle idle time , to compare the idle time with the preset time t1.

If the idle time is greater than the preset time t1, it will enter the semi-junction point self-learning;

If the idling time is less than or equal to the preset time t1, the condition for entering the semi-junction self-learning is not met, and return to step S0;

Described semi-junction self-learning comprises the steps:

Step S1; Step S2; Step S3; Step S4;

S5. Record the information of the determined half joint point to the vehicle CPU in real time, and at the same time overwrite the last record of the half joint point in the vehicle CPU.

That is, after the conditions for entering the half-joint point self-learning are satisfied, step S1 is executed, and steps S2, S3, S4, and step S5 are executed in sequence.

Specifically, the method of KP point self-learning is: execute steps S1 and S2 in sequence, and in step S2, use the displacement detection device 60 and the pressure detection device 70 of the clutch to detect the pressure of the pressure chamber 41 and the displacement of the piston 40 in real time respectively , and transmit the detected data to the vehicle CPU; continue to execute step S3, and the vehicle CPU draws a curve of displacement changing with pressure according to the real-time recorded oil pressure and displacement data to form a spring stiffness curve; then execute steps S4 and S5, and the vehicle The CPU records a new KP point information, and at the same time overwrites the original KP point to complete the KP point self-learning process. During the subsequent use of the car, the pressure detection device 70 transmits the oil pressure information of the pressure chamber 41 to the vehicle CPU. When the oil pressure of the pressure chamber 41 recognized by the vehicle CPU is equal to the pressure value corresponding to the KP point recorded by the vehicle CPU , the vehicle CPU judges that the clutch is in a half-engagement state.

The clutch in this embodiment and the method for finding the half-engagement point of the clutch are different from the clutch and the method for finding the half-engagement point of the clutch in Embodiment 1. The biggest difference is that the clutch in Embodiment 1 and the method for finding the half-engagement point of the clutch are applicable Before the vehicle is used (during the off-line test), the search for the half-engagement point is carried out, and the clutch of the second embodiment has a displacement detection device 60 and a pressure detection device 70. The method for finding the half-engagement point of the clutch in this embodiment is also It is suitable for finding semi-joint points in vehicle use. In this embodiment, the driving intention is judged by comparing the idle time with the preset time t1. If the idle time is greater than the preset time t1, then enter the KP point self-study; if the idle time is less than or equal to the preset time t1, then If the conditions for entering the semi-junction self-learning are not satisfied, return to the initial stage of step S0. Through KP point self-learning, the vehicle CPU will record the latest measured KP point information. In the subsequent driving process, the vehicle CPU will use the latest recorded KP point information as the basis for judging the KP point. The KP point information is constantly updated, which is always the most in line with the current actual condition of the vehicle. Since the clutch has its own displacement detection device 60 and pressure detection device 70, it is convenient to carry out KP point self-learning at any time, so as to maintain the accuracy of KP point every time the vehicle is used, and avoid the change of the IP (protection level) characteristics of the solenoid valve. After the KP point changes due to factors such as clutch wear and tear, the vehicle CPU still uses the KP point measured before the clutch goes offline or during the gearbox assembly process as the basis for judgment, resulting in inaccurate judgment of the KP point.

Wherein, the value of t1 can be set as required, so that the KP point self-learning is completed once during each driving cycle.

Further, the displacement detecting device 60 adopts a displacement sensor, and the displacement sensor may be a contact sensor or a non-contact sensor. In this embodiment, the displacement sensor is connected to the piston 40 to detect the axial displacement length of the piston 40 . The pressure detection device 70 adopts a pressure sensor, and the main hub 20 is provided with a first oil passage 22 and a second oil passage 23, the first oil passage 22 communicates with the pressure chamber 41, and the second oil passage 23 communicates with the pressure chamber 41. The balance chamber 42 is connected, the pressure sensor is arranged in the first oil passage 22, the oil pressure of the first oil passage 22 is the same as the oil pressure of the pressure chamber 41, so the oil pressure detected by the pressure sensor is the pressure chamber 41 oil pressure.

It should be noted that, in the description of the present invention, unless otherwise clearly stipulated and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected, or integrally connected; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations.

To sum up, the clutch of the present invention includes an outer hub, a main hub, a friction plate set, a piston, and a balance piston, and an elastic member is provided on the path where the piston pushes the friction plate set to move axially. The method of finding the half-engagement point of the clutch is to slowly fill the pressure chamber with oil, respectively detect the axial displacement of the piston and the oil pressure in the pressure chamber, and draw the spring stiffness curve accordingly. When the piston continues to move axially and the piston When the contact with the friction plate set is just started (direct contact or indirect contact through the elastic member), the stiffness of the elastic member and the return spring are superimposed, and at the same time hinder the axial movement of the piston, resulting in the slope of the spring stiffness curve acting on the piston Changes occur immediately, resulting in an inflection point, and the pressure point corresponding to the inflection point can be judged as the KP point. The structure of this clutch is simple, the body of the wet clutch is optimized, the method of finding the KP point of the clutch is simple and easy, and the KP point found is more intuitive and accurate, and the influence of interference factors on the search for the KP point is eliminated (such as drag torque ), thereby improving the control accuracy of the wet clutch, which is conducive to improving the smoothness of shifting, improving efficiency, reducing fuel consumption, and is conducive to improving test efficiency and reducing costs. In addition, by adding a displacement detection device and a pressure detection device to the clutch, and adding a KP point self-learning method to the method of finding the half-engagement point of the clutch, the KP point information can be re-measured and recorded every time the car is used, effectively ensuring The accuracy of the KP point avoids the problem of inaccurate judgment of the KP point by the vehicle CPU due to factors such as changes in the IP characteristics of the solenoid valve and clutch wear, and has high application and promotion value.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, some improvements and replacements can also be made, these improvements and replacements It should also be regarded as the protection scope of the present invention.

Claims (8)

1. A clutch is characterized by comprising an outer hub, a main hub, a friction plate group connected in the outer hub, a piston axially and slidably connected to the main hub to press or release the friction plate group, and a balance piston connected to the main hub, wherein the balance piston, the main hub and the piston define a balance cavity, and a pressure cavity is formed between the piston and the main hub;

a return spring group for abutting and compressing the piston when the piston moves axially towards the friction plate group is arranged between the balance piston and the piston, and an elastic piece is arranged on a path for pushing the friction plate group to move axially by the piston;

a first clamp spring for axial limiting is arranged on one side, away from the piston, of the friction plate set, and the elastic part is arranged between the first clamp spring and the friction plate set;

the clutch further comprises displacement detection means for detecting axial displacement of the piston, and pressure detection means for detecting oil pressure of the pressure chamber;

drawing a curve of piston displacement along with the change of the oil pressure of the pressure cavity according to the detection result of the displacement detection device and the detection result of the pressure detection device so as to form a spring stiffness curve of the movement of the piston;

when the piston moves along the axial direction and just starts to contact with the friction plate set, the elastic piece starts to be extruded and generates reverse acting force on the piston, so that the spring stiffness curve has a break point, and a KP point is determined according to the pressure of the break point.

2. The clutch of claim 1, wherein the resilient member is connected to the outer hub and is disposed on a side of the set of friction plates adjacent the piston.

3. A clutch according to claim 1, characterized in that the elastic element is connected to the side of the piston facing the set of friction plates.

4. The clutch according to claim 1, wherein the set of friction plates includes disc-shaped friction plates and steel plates arranged at intervals in sequence, and the elastic member is disposed between the friction plates and the steel plates.

5. The clutch according to any one of claims 1 to 4, wherein the return spring set is provided precompressed between the balance piston and the piston; the elastic part adopts a corrugated spring arranged in the radial direction.

6. The clutch according to claim 1, wherein the displacement detecting means employs a displacement sensor, the pressure detecting means employs a pressure sensor,

the main hub is provided with a first oil duct communicated with the pressure cavity and a second oil duct communicated with the balance cavity; the displacement sensor is connected to the piston, and the pressure sensor is arranged in the first oil duct.

7. A method for finding a clutch half-engagement point, characterised by being implemented with a clutch according to any one of claims 1-6, comprising the steps of:

filling oil into the pressure cavity;

detecting and recording the pressure of the pressure cavity and the displacement of the piston in real time;

drawing a curve of displacement along with pressure change according to the records of oil pressure and displacement to form a spring stiffness curve;

and reading a pressure point corresponding to a break point formed by the change of the spring stiffness, and judging that the pressure point is a half joint point.

8. A method of finding a clutch half-engagement point, comprising the steps of:

judging whether the self-learning condition of the half joint is met: obtaining the idle time of the vehicle, and comparing the idle time with the preset time t 1;

if the idling time is greater than the preset time t1, entering self-learning of the half-joint point;

if the idling time is less than or equal to the preset time t1, the condition for entering the self-learning of the half joint point is not met, and the step of judging whether the condition for entering the self-learning of the half joint point is met is returned;

the semi-joint self-learning comprises the following steps:

filling oil into the pressure cavity;

detecting and recording the pressure of the pressure cavity and the displacement of the piston in real time;

drawing a curve of displacement along with pressure change according to the records of oil pressure and displacement to form a spring stiffness curve;

reading a pressure point corresponding to a break point formed by the change of the spring stiffness, and judging that the pressure point is a half joint point;

and recording the information of the determined half joint to the vehicle CPU in real time, and simultaneously covering the recording of the last half joint in the vehicle CPU.

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