SE534573C2 - Procedure and system for automatic controlled coupling - Google Patents

Description

534 573 stationary, while shifting while driving is performed by the vehicle control system without using the clutch by adjusting the torque delivered from the engine to a suitable level to reduce the torque transmitted at the engagement point of the relevant gears.

According to another type of method, an automatically controlled clutch is used instead for up / down gears, whereby the driver thus, just as in a conventional automatic geared vehicle, only has access to the accelerator pedal and brake pedal.

Control of the automatically controlled clutch is achieved by controlling a clutch actuator with the aid of the vehicle's control system. The clutch actuator can e.g. consist of one or more pneumatically controlled pistons acting on a lever, the coupling being opened / closed by effecting a lever movement by means of said pistons.

The switching actuator can also be of the electric type. An electric type clutch actuator has the advantage that control (opening / closing) of the clutch can be performed faster and with higher accuracy. However, electrical actuators have the disadvantage that components can overheat, with malfunction and / or damaged components as a possible consequence. There is thus a need for a switching actuator where such problems with overheating can be reduced and / or completely avoided.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for controlling a control system-controlled clutch at a vehicle by means of a clutch actuator, whereby the risk of overheating of one or more clutch actuator components can be reduced and / or completely avoided. This object is achieved by a method according to claim 1.

The present invention relates to a method for controlling an automatically controlled clutch at a vehicle by means of a vehicle control system, wherein opening and / or closing of said clutch is effected by means of a clutch actuator comprising at least a first clutch actuator component, said method comprising: - determining a first temperature value for said at least one first clutch actuator component, and - reducing the control system's use of said clutch in driving said vehicle when said first temperature value meets a first criterion, said first criterion being a temperature limit.

Clutch actuators, primarily of the electric type, are exposed in operation to heating not only heat from the usually very hot environment where the clutch actuator is located, which is generally in close proximity to the motor / gearbox, but also by self-heating that occurs due to the current which passes through the components of the clutch actuator when the clutch actuator is active. This self-heating can lead to one or more of the components of the clutch actuator risking overheating and thus being damaged.

The present invention has the advantage that overheating of the components of the clutch actuator can be avoided, which in turn has the advantage that temperature-related damage to the components of the clutch actuator can be avoided.

Furthermore, the clutch actuator may comprise e.g. a microprocessor for controlling e.g. drive circuits for an electric motor. If the temperature of the microprocessor becomes too high, it can, with the help of its own protection circuits, be switched off, with the consequence that the coupling cannot be used at all until the temperature of the microprocessor has dropped to a level where it can be reactivated. By means of the present invention, such undesirable interruptions can also be avoided.

Additional features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments and the accompanying drawings.

Brief description of the drawings Pig. 1a shows a driveline in a vehicle in which the present invention can be used to advantage.

Fig. 1b shows an exemplary control unit in a vehicle control system.

Fig. 2 shows the clutch and clutch actuator for the vehicle shown in Fig. 1a in more detail.

Fig. 3 is a flow chart illustrating an exemplary method of controlling the clutch actuator according to an exemplary embodiment of the present invention.

Detailed Description of Exemplary Embodiments Fig. 1a shows an exemplary driveline in a heavy vehicle 100, such as a truck, bus or the like, according to an exemplary embodiment of the present invention. The vehicle 100 schematically shown in Fig. 1a comprises only one axle with drive wheels 113, 114, but the invention is also applicable to vehicles where more than one axle is provided with drive wheels. The driveline comprises an internal combustion engine 101, which is connected in a conventional manner, via a shaft 102 emanating on the internal combustion engine 101, usually via a flywheel (not shown), to an automatically shifted gearbox 103 via a clutch 106.

In the case of heavy vehicles that are largely used for road / motorway use, however, as mentioned above, automatic gearboxes in the traditional sense are not usually used, but instead a control system-controlled shifting of "manual" gearboxes is used. Partly because manual gearboxes are significantly cheaper to manufacture, but also because they have a higher efficiency, and thus lower fuel consumption.

The clutch 106 consists of an automatically controlled clutch. Furthermore, the coupling 106 is of the lamella type, i.e. one with a first gearbox part, such as e.g. the associated shaft 118 of the input shaft 103, slotted friction member 110 selectively engages the engine flywheel 102 to transmit driving force from the internal combustion engine 101 to the drive wheels 113, 114 via the gearbox 103. The engagement of the clutch plate 110 with the output shaft 102 of the engine is controlled by a pressure plate 111, which is displaceable laterally by means of e.g. a lever 112, the operation of which is controlled by a clutch actuator 115.

The action of the clutch actuator 115 on the lever 112 is in turn controlled by the control system of the vehicle, in this case by means of a control unit 116. The clutch actuator is described in more detail below with reference to Fig. 2.

Control systems in modern vehicles usually consist of a communication bus system consisting of one or more communication buses for interconnecting a number of electronic control units (ECUs), or controllers, and various components located on the vehicle. Such a control system can comprise a large number of control units, and the responsibility for a specific function can be divided into more than one control unit.

For the sake of simplicity, Fig. 1a shows only two such electronic control units 116, 117, which in this embodiment control motor 101, clutch 106 and gearbox 103 respectively (two or more of motor, gearbox and clutch may alternatively be 534 573 arranged to be controlled by one and the same control unit, or other, not shown control units).

Control units of the type shown are normally arranged to receive sensor signals from different parts of the vehicle, e.g. from gearbox, engine, clutch and / or other control units or units on the vehicle. The control of the control units is normally dependent on both signals from other control units, e.g. the control of the control actuator 115 of the control unit 116 is likely to e.g. depend on information such as received from the control unit responsible for the function of the gearbox 103, as well as from the control unit (s) controlling engine functions, such as e.g. the control unit 117.

The control units are further arranged to emit control signals to various parts and components of the vehicle, such as e.g. motor, clutch and gearbox for controlling these. The present invention can be implemented in any of the above control units, or in any other applicable control unit in the vehicle control system.

The control of various parts and components of the vehicle, such as the clutch actuator, is often controlled by programmed instructions.

These programmed instructions typically consist of a computer program, which when executed in a computer or controller causes the computer / controller to perform the desired control, such as method steps of the present invention.

The computer program is usually a computer program product 109 stored on a digital storage medium 121 (see Fig. 1b) such as, for example: ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), Flash Memory, EEPROM (Electrically Erasable PROM), a hard disk drive, etc., in or connected to the control unit and executed by the control unit. Thus, by changing the instructions of the computer program 10 15 20 25 30 534 573, the behavior of the vehicle in a specific situation can be adjusted.

An exemplary control unit (control unit 116) is schematically shown in Fig. 1b, wherein the control unit 116 may in turn comprise a calculation unit 120, which may be constituted by substantially any suitable type of processor or microcomputer, e.g. a Digital Signal Processor (DSP), or an Application Specific Integrated Circuit (ASIC).

The calculation unit 120 is connected to a memory unit 121 arranged in the control unit 116, which provides the calculation unit 120 e.g. the stored program code 109 and / or the stored data calculation unit 120 need to be able to perform calculations. The calculation unit 120 is also arranged to store partial or final results of calculations in the memory unit 121.

Furthermore, the control unit 116 is provided with devices 122, 123, 124, 125 for receiving and transmitting input and output signals, respectively. These input and output signals may contain waveforms, pulses, or other attributes, which of the input signals devices 122, 125 may be detected as information and may be converted into signals which may be processed by the computing unit 120. These signals are then provided to the computing unit 120. The devices 123, 124 for transmitting output signals are arranged to convert signals obtained from the calculation unit 120 for creating output signals by e.g. modulate the signals, which can be transmitted to other parts of the vehicle's control system and / or the component (s) for which the signals are intended.

Each of the connections to the devices for receiving and transmitting input and output signals, respectively, may consist of one or more of a cable; a data bus, such as a CAN bus 10 15 20 25 30 534 573 (Controller Area Network bus), a MOST bus (Media Orientated Systems Transport), or any other bus configuration; or by a wireless connection.

The vehicle 100 further comprises drive shafts 104, 105, which are connected to the vehicle drive wheels 113, 114, and which are driven by a shaft 107 emanating from the gearbox 103 via an end gear 108, such as e.g. a usual differential.

Fig. 2 shows the switching actuator 115 in more detail. The clutch actuator shown in Fig. 2 is only a non-limiting example of an electrically controlled clutch actuator. As mentioned above, the clutch is operated by the clutch actuator 115 opening / closing the clutch by displacing the pressure plate 111 in the axial direction along the input shaft 118 of the gearbox by means of the lever 112.

The lever is rotated about a pivot axis 201, and the rotation of the lever is controlled by a piston 202 acting in a hydraulic cylinder 203. The lever is connected to the pressure plate III via a disengagement bearing 119. The disengagement bearing and the pressure plate are connected via an intermediate spring (not shown). ), whereby, when the lever pulls the disengagement bearing (ie for the disengagement bearing to the right in the figure, where the disengagement bearing is shown in the right extreme position, ie fully open coupling), the pressure plate (via the spring) will pull apart (open) the coupling.

Conversely, the spring will compress the flywheel, lamella, and pressure plate (ie, close the clutch) as the force acting on the lever of the piston 202 is reduced.

The cylinder 203 receives its control pressure from a second hydraulic cylinder 205. The cylinder 205 comprises a displaceable piston 206, the displacement of which is controlled by a threaded rod 210 whose movement is in turn controlled by an electric motor 208.

The rotation of the electric motor 208 is converted into a linear movement of the threaded rod 210 by means of a ball screw (not shown). 534 573 The ball screw is rotated by the electric motor 208, whereby the threaded rod can be reciprocated in the direction of the arrows by rotation of the electric motor, and thus the ball screw, whereby the linear movement of the threaded rod is transmitted to a linear movement of the piston 206.

Displacement of the piston 206 into the cylinder 205 (ie to the left in the figure) increases the hydraulic pressure in the pressure chamber 205a, and thus also the pressure in the pressure chamber 203a connected to the pressure chamber 205a in the cylinder 203. When the pressure generated by the piston 206 in the pressure chamber 203a (205a ) generates a force on the piston 202 which exceeds the force generated by the spring between the pressure plate and the release bearing, the coupling will thus be opened as above. Then, when the pressure in the pressure chamber 203a is lowered by reversing the direction of rotation of the engine so that the piston 206 moves to the right in the figure, the clutch will close when the spring force again exceeds the force generated by the hydraulic fluid.

With the help of the electric motor a very fast opening / closing of the coupling can be achieved, while control of the position of the lever, and thus the pressure plate, is controlled with very high precision to achieve an opening / closing of the driveline (by means of the coupling) in a way as little as possible is noticeable to the driver.

The electric motor 208 may be of any applicable type and in the present example is a brushless DC motor. A brushless DC motor is basically identical to a 3-phase permanent magnet motor. The electric motor 208 is supplied via drive stage 212, with drive circuits, e.g. consisting of two transistors for each phase winding. Opening / closing of the transistors is controlled by a microprocessor 213, which together with said drive stage 212 may be arranged on a circuit board 214. Microprocessor 213 and drive stage 212 are supplied with power via a power supply 215, and the microprocessor receives control signals 216, e.g. from the control unit 116, for suitable control of said drive stage and thus the electric motor for effecting the desired opening / closing of the coupling.

Due to the forces and the speed required when opening / closing the coupling, the electric motor draws a lot of current when opening / closing the coupling, which in turn leads to heating of both the electric motor 208 and the electric motor drive stage 212.

If said drive stage 212 is arranged on the same circuit board 214 as the microprocessor 213 according to the above, heat is also transferred to it. Furthermore, the clutch actuator is usually located on the gearbox, and thus in the vicinity of the internal combustion engine, with the consequence that the environment of the clutch actuator can be very hot. This leads to the components of the clutch actuator being heated not only by use when opening / closing the clutch, but also by heat radiation radiated from the motor. In addition, heating takes place through heat flow through the cast iron of the gearbox.

Taken together, this heating can cause one or more of the clutch actuator components to overheat. For example. the microprocessor and / or one or more drive circuits and / or the electric motor may become overheated. If any of the clutch actuator components becomes overheated, this is likely to result in permanent damage which may result in the clutch actuator having to be replaced. This in turn leads to the vehicle becoming immobile and requires salvage for transport to the workshop. Such scenarios can be avoided by means of the present invention.

According to the present invention, the method of the control system to use the clutch (clutch actuator) changes when such a risk of overheating exists. Fig. 3 shows an exemplary flow diagram of an exemplary method 300 according to the present invention. In step 301, a representation of a temperature T1 of at least one switching actuator component is determined. This temperature T1 can e.g. determined for the component that is likely to overheat first. For example. For example, the various components of the clutch actuator may have different temperature tolerances, a temperature being determined for the clutch actuator component that most quickly reaches critical temperature. This component can e.g. be determined in advance, e.g. using product specifications and / or actual samples.

Alternatively, a temperature may be determined for two or more of the components of the clutch actuator so as to reduce the risk of any component inadvertently reaching critical temperature.

According to one embodiment, the one or more temperatures T1 are determined directly by means of one or more temperature sensors. For example. For example, temperature sensors 217, 218 may be provided on the circuit board and / or the electric motor. Furthermore, microprocessors usually comprise a built-in temperature sensor, whereby this can also be used in said temperature determination.

Instead of using temperature sensors, in an alternative exemplary embodiment, an ambient temperature may be used instead. This ambient temperature e.g. can be obtained via the vehicle's control system from an existing temperature sensor at or near the engine and / or gearbox, whereby temperatures for the components of the clutch actuator can then be modeled based on said temperature. For example. For example, the temperature of the drive stage and / or the electric motor can be modeled by means of said determined ambient temperature and the current which has passed through the drive stage / electric motor for a certain time. This current can e.g. determined by means of one or more current sensors.

When said one or more temperatures T1 have been determined in step 301, the process proceeds to step 302, where it is determined whether said one or more determined temperatures T1 meet a first criterion. This criterion can e.g. consists of a temperature limit Tg. In this way, measures can be taken if it is determined that the determined temperature exceeds the temperature limit. The temperature limit consists of a temperature which is set to a lower temperature than the critical temperature Th of the switching actuator. This temperature limit Tg can often be relatively close to the critical temperature, and e.g. consists of a temperature 5 ° or 10 ° lower compared to the critical temperature. Examples of critical temperature for e.g. drive circuits, microprocessor, electric motor, can consist of temperatures in the range 100-150 °, but the actual critical temperature naturally depends on the specific components included in the switching actuator. In addition to the components exemplified above, the clutch actuator may also include other temperature sensitive components.

Said first criterion can, instead of consisting of a temperature limit Tg, also consist of e.g. a temperature derivative. By continuously determining a temperature for one or more clutch actuator components as above, a derivative can be determined, and if the derivative is high, i.e. in the event that the component temperature increases rapidly, measures can be taken before a temperature limit is reached as above to ensure that appropriate measures are taken before the critical temperature is reached. If it is determined in step 302 that action must be taken, the procedure proceeds to step 303. Otherwise, the procedure returns to step 301 to perform a new temperature determination. In step 303, measures are taken to reduce the temperature of the switching actuator. This is achieved according to the present invention in that the vehicle, compared to normal clutch use during normal driving of the vehicle, is driven in such a way that the vehicle control system reduces, or completely (in all or some situations where the clutch actuator is normally used) ceases to use the clutch actuator. This can e.g. is achieved by setting the vehicle's driving to a mode for reduced clutch use. Said reduced clutch use is thus activated in step 303, and may comprise one or more of a number of measures for reducing the temperature of the clutch actuator.

Examples of such measures are given below. The coupling is normally arranged so that it is in an unaffected state, ie. when the clutch actuator is not activated, by spring force is kept closed. As soon as the coupling is to be opened, e.g. when shifting, additional heat is generated due to the current required by the electric motor 208 to operate the arm 211 to open the clutch.

According to an embodiment of the present invention, the use of the clutch actuator during shifting is reduced by instead of opening the clutch at each shift, so as to obtain a torque-relieved gearbox during shifting, the torque delivered from the vehicle engine is controlled to a level which gives rise to a (substantially) torque-relieved driveline, whereby the current gear can be disengaged, and new gear is engaged without opening the clutch, and thus without activating the clutch actuator, without risking damage to the vehicle's driveline. This type of shifting is common in vehicles where a clutch pedal is used to start the vehicle from a standstill, while all other shifting is performed by the vehicle's steering system using the clutch.

By proceeding in this way, all shifting during travel can thus take place without the use of the clutch, whereby the temperature increase in the clutch actuator stops and the temperature in most cases also begins to fall. By in this way reducing, or completely ceasing, the use of the clutch actuator, overheating of its constituent components can thus be avoided in a way that still allows full driveability and only entails possible. comfort disturbances for the vehicle driver. Once steps have been taken in step 303, the process proceeds to step 304, continuously monitoring the temperature of the one or more clutch actuator components. When the temperature T1 has dropped to a certain level, e.g. 5 ° or 10 ° or other suitable number of degrees below said limit level, the process may proceed to step 305, where operation of the vehicle returns to normal use of the clutch actuator.

In step 303, alternatively, or in addition to the above, additional measures may be taken. When braking to a stop, the clutch is normally opened so that the vehicle can be stopped without an engine stop. Instead of opening the clutch, neutral gear can be engaged when braking to a stop so that the vehicle can be stopped without opening the clutch.

Alternatively, the time the clutch is open for stationary vehicles can be limited. An example of a solution for limiting the time the connection is open is shown in the parallel Swedish patent application "Procedure and system for connection" (application number: 1050098-1), with the same filing date as the present application, and with the same applicant.

Furthermore, when the vehicle's gear position is in the driving position when the vehicle is stationary, a gear is normally engaged, whereby the clutch is also open so that it can be closed quickly when the vehicle is to be set in motion again. According to an exemplary embodiment, the gearbox is instead engaged only when the vehicle is de facto to be set in motion, which e.g. can be determined by the driver pressing the accelerator pedal. This leads to the clutch only being opened once the driver has pressed the accelerator pedal, thus long downtimes with open clutch can be avoided, and the temperature of the clutch actuator components is given a chance to recover. Even if this means a certain delay when driving away, the vehicle can still be driven in principle as normal with only minor comfort disturbances as a consequence.

Furthermore, control systems for heavy vehicles are normally arranged in such a way that they, based on e.g. road slope and current vehicle weight, select a suitable starting gear, ie. the gear on which the vehicle is to be slid into operation by means of the clutch.

The starting gear is normally selected as high as possible in order to be able to quickly accelerate the vehicle to the desired speed without frequent shifting. According to the present invention, instead, the lowest gear, or at least one low gear, is engaged at start-up so that slip on the clutch takes place for as short a time as possible so that the clutch actuator is activated for as short a time as possible.

In addition to the above measures, the vehicle's one or more cooling fans can also be run at a high or maximum level in order to cool down the components surrounding the clutch actuator as much as possible, in order to thus try to reduce its temperature.

The operation of the vehicle in said mode for reduced clutch use may utilize all of the above measures or only one or an arbitrary combination of two or more of said measures. After the vehicle (control system) in step 305 has returned to normal use of the clutch, the process returns to step 301 for new temperature determination.

The present invention thus has the advantage that overheating of the clutch actuator components can be avoided, whereby also temperature-related damage to the clutch actuator can be avoided. This in turn means that situations where the vehicle becomes unusable, and thus requires salvage for transfer to a workshop, can be avoided.

The invention has been described above in connection with a specific type of electrically controlled connection. It should be noted, however, that Fig. 2 only shows an exemplary principle for an electrically controlled switching actuator, and that electrically controlled switching actuators according to various principles are described in the prior art. The present invention is applicable regardless of the actual design of the clutch actuator, as long as electrical components with associated overheating hazard are present. Although various embodiments of the present invention have been exemplified above, one skilled in the art will recognize that variations and modifications may be made without departing from the invention. Thus, the invention is not limited except as set forth in the appended claims.

Claims (16)

10 15 20 25 534 573 17 Patent claims A method of controlling an automatically controlled clutch (106) at a vehicle (100) by a vehicle control system, wherein opening and / or closing of said clutch (106) is effected by means of a clutch actuator (115) comprising at least a first clutch actuator component ( 208, 212, 213, 214), characterized in that said method comprises: - determining a first temperature value for said at least one first clutch actuator component (208, 212, 213, 214), and - reducing the control system's use of said clutch (106) in driving said vehicle (100) when said first temperature value meets a first criterion, said first criterion being a temperature limit. The method of claim 1, wherein the control system is put into a temperature reduction mode when said first temperature value meets said first criterion, wherein in said temperature reduction mode the use of the clutch is reduced or completely stopped in at least a first situation compared to normal clutch use when driving the vehicle (100). The method of claim 1 or 2, wherein said clutch actuator (115) comprises a plurality of clutch actuator components (208, 212, 213, 214), and wherein temperature values are determined for said first clutch actuator component (208, 212, 213, 214) and at least one further clutch actuator component (208, 212, 213, 214). 10 15 20 25 30 534 573 18 A method according to any one of claims 1-3, wherein said one or more temperatures are determined by means of one or more temperature sensors (217, 218). A method according to any one of claims 1-3, wherein said one or more temperature values are determined by means of at least one ambient temperature. A method according to claim 5, wherein said ambient temperature is obtained by means of a temperature sensor present at said engine (101) and / or gearbox (103). A method according to claim 5 or 6, wherein said one or more temperature values are determined by means of modeling based on said determined ambient temperature. A method according to any one of claims 1-7, wherein a plurality of successive determinations of said first temperature value are performed for at least said first clutch actuator component (208, 212, 213, 214), said first criterion being determined based on a derivative of said temperature value determinations. A method according to any one of the preceding claims, wherein the method further comprises: - determining a plurality of consecutive temperature values for said at least one clutch actuator component (208, 212, 213, 214), and - returning to normal use of said clutch (106) when said temperature value is below a second temperature limit, said second temperature limit being below said first temperature limit. A method according to any one of the preceding claims, wherein said clutch actuator (115) is an electric clutch actuator. 10 15 20 25 30 534 573 19 The method of claim 10, wherein said at least one (208, 212, 213, 214) is one or more of the group: microprocessor (213), drive stage for an electric motor (212), electric motor (208). clutch actuator component A method according to any one of the preceding claims, wherein, in said reduced use of said clutch (106), said reduction is performed by one or more measures of the group: - shifting without opening the clutch (106), - loading of lower gear than normal when starting the vehicle (100) from a standstill, - loading neutral gear when braking to a stop, - when stationary, loading gear only when the vehicle (100) is to be set in motion, - when stationary, load neutral gear and close clutch (106) when a first time has elapsed Computer program comprising program code, which when said program code is executed in a computer causes said computer to perform the method according to any one of claims 1-12. A computer program product comprising a computer readable medium and a computer program according to claim 13, wherein said computer program is included in said computer readable medium. A system for controlling an automatically controlled clutch (106) at a vehicle by means of a vehicle control system, wherein opening and / or closing of said clutch (106) is effected by means of a clutch actuator (115) comprising at least a first clutch actuator component (208, 212 , 213, 214), characterized in that the system comprises: - determining means for determining a first temperature value of said at least one first clutch actuator component (208, 212, 213, 214), and - means for reducing the control system's use of said clutch (106) when driving said vehicle (100) when said first temperature value meets a first criterion, said first criterion being a temperature limit. Vehicle, characterized in that it comprises a system according to claim 15.