Clutch pedal torque limitation

Abstract

Method for adjusting the torque input from a vehicle engine to a clutch, wherein the method includes adjusting the torque when: - the position of the coupling is within a predetermined range of positions; - the coupling is held within the predetermined range of positions for a first predetermined period of time; and - the vehicle's transmission maintains a selected gear for a second predetermined period of time, wherein the clutch position correlates with a clutch pedal position, wherein the predetermined range of clutch positions correlates with a predetermined range of clutch pedal positions, and wherein the predetermined range of clutch pedal positions is 5 to 35 percent of the clutch pedal's maximum travel from an unpressed position.

Description

[0001] This invention relates to a method for adjusting the torque input from a power machine to a clutch of a vehicle and relates in particular, but not exclusively, to a method for limiting the torque input to the clutch when it is determined that there is slippage between the clutch discs.

[0002] Slippage between clutch discs causes heat generation. Prolonged slippage and excessive heat generation reduce clutch life and can damage the clutch and / or flywheel, leading to a reduced torque transmission capacity and even clutch failure.

[0003] Resting a foot on the clutch pedal while driving (clutch driving) reduces the clamping force on the clutch plates, thereby decreasing the clutch's torque capacity. Clutch slippage can be induced by a combination of reduced clamping force and sufficient engine torque, with the most challenging conditions being high-speed, high-load driving scenarios. If slippage occurs under these conditions, for example, while climbing an incline and / or towing, a significant amount of heat can be generated. If the generated heat exceeds the clutch's maximum operating temperature for an extended period, permanent clutch damage can result.

[0004] Resting a foot on the clutch pedal also increases wear on the release bearing. These consequences are undesirable for customers and also negatively impact manufacturers, both in terms of warranty costs and their reputation.

[0005] Studies have shown that a significant number of drivers keep their foot on the clutch pedal while driving. However, clutch slippage is a necessary part of operation during starting and gear changes. Therefore, providing a method to limit clutch plate slippage is considered advantageous when it is determined that the slippage occurs as a result of the driver keeping their foot on the clutch while driving.

[0006] DE 10 2006 060 285 A1, DE 10 2009 040 388 A1 and JP 2001- 107 993 A disclose generic methods for operating couplings.

[0007] The objective technical problem to be solved can be seen as eliminating or at least reducing the disadvantages of the prior art. This problem is solved by the subject matter of independent claim 1.

[0008] According to a first aspect of the present invention, a method for adjusting the torque input from a vehicle engine to a clutch is provided, wherein the method comprises adjusting the torque when: the position of the clutch is within a predetermined range of positions; the clutch is held within the predetermined range of positions for a first predetermined period of time; and the vehicle's transmission maintains a selected gear for a second period of time.

[0009] The method may further include providing a signal to adjust the torque input from the engine to the clutch, after: determining the position of the clutch and comparing the position of the clutch with the predetermined range of positions; determining a first period for which the clutch is held in position and comparing the first period with the first predetermined duration; and determining a second period for which a transmission of the vehicle maintains a selected gear and comparing the second period with the second predetermined duration.

[0010] The method may further include providing the signal to adjust the torque input from the motor to the clutch in the event that: the position of the clutch is outside the predetermined range of positions; the first period is greater than the first predetermined duration; and the second period is greater than the second predetermined duration.

[0011] The procedure may further include determining a set of operating variables for the clutch and comparing this set of operating variables with predetermined values. Determining the set of operating variables for the clutch and comparing it with threshold values ​​may involve: determining the input torque from the motor to the clutch and comparing this input torque with a predetermined input torque; and / or calculating a speed difference in the clutch and comparing this speed difference with a predetermined speed difference.

[0012] The method can further include providing the signal to adjust the torque input from the engine to the clutch if: the input torque from the engine to the clutch is greater than the predetermined input torque, or the speed difference in the clutch is greater than the predetermined speed difference. The speed difference in the clutch can be calculated by comparing the engine speed with the speed of the wheels, the transmission input shaft, or the speed of any other suitable vehicle component. The transmission input shaft speed can be determined using a speed sensor. The selected transmission gear can be determined using a gear selector sensor and / or a transmission input shaft sensor.

[0013] The signal for adjusting the torque input to the clutch can be configured to limit the torque input from the engine to the clutch.

[0014] The clutch position correlates with the clutch pedal position and can also correlate with the clutch slave cylinder position and / or pressure in the clutch line. The clutch position can correlate with a static clutch torque capacity and / or a dynamic clutch torque capacity. The predetermined range of clutch positions correlates with a predetermined range of clutch pedal positions and can also correlate with a predetermined range of clutch slave cylinder positions and / or a predetermined range of pressures in the clutch line. The predetermined range of clutch pedal positions is 5 to 35 percent of the maximum clutch pedal travel from an un-depressed position.

[0015] The procedure may further include determining the amount of heat energy generated by the coupling and the amount of heat energy dissipated from the coupling.

[0016] The method may further include calculating an operating temperature of the coupling, wherein the operating temperature corresponds to the amount of heat energy generated by the coupling minus the heat energy dissipated from the coupling, and comparing the operating temperature with a predetermined operating temperature.

[0017] The method may further include providing the signal to adjust the torque input from the motor to the clutch when the operating temperature approaches, exceeds, or equals the predetermined operating temperature.

[0018] The procedure can further include, in scenarios requiring a significant input torque, canceling the signal to restrict the torque input from the motor to the clutch.

[0019] The method may further include providing an indicator to an operator. The indicator may be a visual, audible, vibrotactile, and / or similar mechanical-dynamic alarm system. The indicator may be a signal that the operator's foot is on the clutch pedal.

[0020] According to a second aspect of the present invention, a method for adjusting the torque input from a vehicle engine to a clutch is provided, wherein the method comprises adjusting the torque when: the position of the clutch is within a predetermined range of positions; the clutch is held within the predetermined range of positions for a first predetermined period of time; and the vehicle's transmission maintains a selected gear for a second predetermined period of time; and measures are taken to prevent damage to the clutch.

[0021] The measures may include, for example, any of the remedies listed above, such as reducing the torque applied to the clutch or sending a signal to the driver to provide a warning that the driver has a foot on the clutch while the vehicle is in motion.

[0022] A system, for example a controller, can be configured to perform one of the procedures mentioned above.

[0023] To better understand the present revelation and to illustrate how it can be put into practice, reference is now made to the accompanying drawing as an example. It shows: Fig. 1 A flowchart illustrating a procedure for adjusting the torque input to a clutch when it is determined that a driver has a foot on the clutch pedal.

[0024] Clutch slippage can be reduced by adjusting the torque input to the clutch. A method for adjusting the torque input from an engine to the clutch of a vehicle is described in Fig.Figure 1 shows the torque input to the clutch. The torque input to the clutch is set when: the clutch position is within a predetermined range of positions; the clutch is held within the predetermined range of positions for a first predetermined period of time; and the vehicle's transmission maintains a selected gear for a second period of time.

[0025] The procedure includes three criteria that must be met in order for the torque to be adjusted: criterion 1 concerns the position of the clutch; criterion 2 concerns the period of time the clutch has been held in that position; and criterion 3 concerns the period of time the vehicle's transmission has maintained a selected gear.

[0026] These are as follows: Criterion 1 involves determining the clutch position and comparing it to a predetermined range of positions; Criterion 2 involves determining a first period for which the clutch is held in position and comparing it to the first predetermined duration; and Criterion 3 involves determining a second period for which the vehicle's transmission maintains a selected gear and comparing it to the second predetermined duration. The selected gear can be determined by a gear position sensor and / or a transmission input shaft sensor.

[0027] Depending on the results of the comparisons, the procedure provides a signal A to adjust the torque input from the motor to the clutch. Signal A can be configured to limit the torque input from the motor to the clutch.

[0028] In a first embodiment of the present invention, signal A is provided to restrict the torque input from the motor to the clutch in the case that criteria 1 to 3 are met, wherein: for criterion 1, the position of the clutch is outside the predetermined range of positions; for criterion 2, the first period is greater than the first predetermined duration; and for criterion 3, the second period is greater than the second predetermined duration.

[0029] Criteria 1, 2, and 3 can be fulfilled in any order or concurrently. Similarly, one or more of criteria 1, 2, and 3 can be continuously monitored, or the determinations and / or comparisons can be carried out with an appropriate frequency.

[0030] The clutch position correlates with the clutch pedal position, with the predetermined clutch travel range corresponding to a predetermined range of clutch pedal positions. This predetermined range of clutch pedal positions is 5 to 35 percent of the clutch pedal's maximum travel from a fully disengaged position, indicating that a driver's foot rests on the clutch while driving.

[0031] The clutch position can correlate with the position of a clutch slave cylinder and / or a pressure in a clutch line, with the predetermined clutch range corresponding to a predetermined range of clutch slave cylinder positions and / or a predetermined range of clutch line pressures. The clutch position can also correlate with a static clutch torque capacity and / or a dynamic clutch torque capacity.

[0032] Signal A can therefore be provided if it has been determined that, when driving in a single gear, the driver's foot remains on the clutch pedal for a longer period than the second predetermined period.

[0033] The procedure further includes criterion 4 (not shown), which can be used as a check to determine whether the clutch actually slips after criteria 1, 2, and 3 have been met. Criterion 4 involves determining a set of operating variables for the clutch and comparing this set of operating variables with predetermined values ​​for the set of operating variables.

[0034] More specifically, criterion 4 comprises determining the input torque from the engine to the clutch and comparing this input torque to a predetermined input torque; and / or calculating a speed difference in the clutch and comparing this speed difference to a predetermined speed difference. Clutch slip is determined when the input torque from the engine to the clutch is greater than the predetermined input torque and / or the speed difference in the clutch is greater than the predetermined speed difference. The speed difference in the clutch can be calculated by comparing the engine speed to the speed of any other suitable component of the vehicle. For example, speeds in the clutch can be calculated by comparing the wheel speed and the engine speed, as these signals are readily available in modern vehicles.Alternatively, clutch speeds can be calculated by comparing the transmission input shaft speed and the engine speed, which can provide a more accurate difference in clutch speeds if the appropriate sensors are present in the vehicle. The transmission input shaft speed can be determined using a speed sensor.

[0035] Criterion 4 is met if: the input torque from the engine to the clutch is greater than the predetermined input torque; and / or the difference in speeds in the clutch is greater than the predetermined difference in speeds.

[0036] In a second embodiment of the present invention, signal A is provided to limit the torque input from the motor to the clutch in the case that criteria 1 to 4 are met.

[0037] The method may further include criterion 5 (not shown), which involves determining the amount of heat energy generated by the coupling and the amount of heat energy dissipated from the coupling. The operating temperature of the coupling is equal to the amount of heat energy generated by the coupling minus the heat energy dissipated from the coupling, comparing the operating temperature to a threshold value.

[0038] Criterion 5 is met if: the operating temperature approaches, is greater than, or corresponds to a predetermined operating temperature.

[0039] In a third embodiment of the present invention, signal A is provided to limit the torque input from the motor to the clutch in the case that criteria 1 to 3 are met; and criteria 4 and / or 5 are met.

[0040] The procedure may further include criterion 6 (not shown), which determines whether the clutch slips due to necessary driver inputs, for example, when the accelerator pedal is depressed substantially, i.e., to approximately 90 to 100% of its travel, during an overtaking maneuver. The restriction of torque under such circumstances may endanger the vehicle's occupants.

[0041] If, in a fourth embodiment of the invention, it is determined that the torque input from the motor to the clutch is based on a scenario that requires a substantial input torque, then signal A can be canceled and the torque input from the motor to the clutch can be restricted.

[0042] Depending on the results of the comparison and / or the provisions of criteria 1 to 6, the procedure may also include providing the vehicle driver with an indication that the clutch is slipping. As part of a human-machine interface (HMI) strategy, the indication may be provided through device group announcements and sounds, vibrations, or similar mechanical-dynamic cues induced at the clutch pedal. This may serve to alert the driver that their foot is on the clutch pedal and may prompt them to take action to avoid damaging the clutch.

[0043] If it is detected that a driver's foot is on the clutch pedal and the prescribed criteria mentioned above are met, a potential implementation approach would be to first prompt the driver via the HMI to completely remove their foot from the clutch pedal. If this prompt is ignored, the engine torque can be limited to protect the clutch. This process could also be accompanied by appropriate HMI warnings.

[0044] A clutch protection strategy can be implemented in a vehicle's software using existing sensor sets available in modern vehicles. Such a solution can be used to reduce warranty claims on existing clutches and / or lower clutch manufacturing costs due to reduced lifecycle requirements. Customers can benefit from fewer instances of reduced wheel torque due to premature clutch wear and also from fewer clutch failures. Furthermore, wear on the thrust bearings can be reduced, allowing manufacturers and / or suppliers to benefit from lower warranty costs and an improved reputation for quality.

[0045] Furthermore, a clutch protection strategy as disclosed in the present invention can lead to a reduction in clutch wear and defects during high-torque maneuvers, where the clutch clamping force may be at its upper limit and a reduction in clamping force due to the foot resting on the clutch pedal during such maneuvers may exacerbate clutch slippage and wear problems.

Claims

[1] Method for adjusting the torque input from a vehicle engine to a clutch, the method comprising adjusting the torque when: - the position of the coupling is within a predetermined range of positions; - the coupling is held within the predetermined range of positions for a first predetermined period of time; and - the vehicle's transmission maintains a selected gear for a second predetermined period of time, wherein the clutch position correlates with a clutch pedal position, wherein the predetermined range of clutch positions correlates with a predetermined range of clutch pedal positions, and wherein the predetermined range of clutch pedal positions is 5 to 35 percent of the clutch pedal's maximum travel from an unpressed position. [2] Method according to claim 1, wherein the method further comprises providing a signal for adjusting the torque input from the motor to the clutch, according to: - Determining the position of the coupling and comparing the position of the coupling with the predetermined range of positions; - Determining an initial period for which the clutch is held in position and comparing this initial period with the initial predetermined duration; and - Determining a second period of time for which the vehicle's transmission maintains the selected gear, and comparing the second period of time with the second predetermined period of time. [3] Method according to claim 2, wherein the method further comprises providing the signal for adjusting the torque input from the motor to the clutch in the case that: - the position of the coupling is outside the predetermined range of positions; - the first period is longer than the first predetermined duration; and - the second period is longer than the second predetermined time period. [4] Method according to claim 3, wherein the method further comprises determining a set of operating variables for the coupling and comparing the set of operating variables with predetermined values ​​for the set of operating variables. [5] Method according to claim 4, wherein determining the set of operating variables for the coupling and comparing the set of operating variables with predetermined values ​​includes the following: - Determining the input torque from the motor to the clutch and comparing the input torque with a predetermined input torque; and / or - Calculating a difference in rotational speeds in the clutch and comparing the difference in rotational speeds with a predetermined difference in rotational speeds. [6] Method according to claim 5, wherein the method further comprises providing the signal for adjusting the torque input from the motor to the clutch in the case that: - the input torque from the engine into the clutch is greater than the predetermined input torque, or the difference in speeds in the clutch is greater than the predetermined difference in speeds. [7] Method according to claim 6, wherein the difference in rotational speeds in the clutch is calculated by comparing the rotational speed of the engine with the rotational speed of the wheels, the transmission input shaft or the rotational speed of any other suitable component of the vehicle. [8] Method according to any one of claims 2 to 7, wherein the signal is configured to limit the torque input from the motor to the clutch. [9] Method according to any of the preceding claims, wherein the position of the clutch correlates with the position of a clutch slave cylinder and / or a pressure in a clutch line. [10] Method according to any of the preceding claims, wherein the position of the clutch correlates with a static clutch torque capacity and / or a dynamic clutch torque capacity. [11] Method according to claim 10, wherein the predetermined range of positions of the clutch correlates with a predetermined range of positions of the clutch slave cylinder, a predetermined range of pressures in the clutch line and / or a predetermined range of the static clutch torque capacity and / or the dynamic clutch torque capacity. [12] Method according to any of the preceding claims, wherein the method further comprises determining the amount of heat energy generated by the coupling and the amount of heat energy dissipated from the coupling. [13] Method according to claim 12, wherein the method further comprises calculating an operating temperature of the coupling, wherein the operating temperature corresponds to the amount of heat energy generated by the coupling less the heat energy dissipated from the coupling, and comparing the operating temperature with a predetermined operating temperature. [14] Method according to claim 13, wherein the method further comprises providing the signal to adjust the torque input from the motor to the clutch when the operating temperature approaches, is greater than or equals the predetermined operating temperature. [15] Method according to claim 2, wherein the method further comprises, in scenarios requiring a substantial input torque, canceling the signal to adjust the torque input from the motor to the clutch. [16] Method according to any of the preceding claims, wherein the method further comprises providing a display for an operator. [17] Method according to claim 16, wherein the display comprises a visual, an acoustic, a vibrotactile and / or a mechanical-dynamic alarm system. [18] Method according to claim 16 or 17, wherein the indicator signals that the operator's foot is on the clutch pedal.

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