JP2005083435A - Road surface condition determining device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a road surface condition determining device for a vehicle capable of preventing erroneous determination of a road surface condition and improving determination precision. <P>SOLUTION: This road surface condition determining device for the vehicle for determining a road surface condition based on the result of comparison of a predetermined detected value in a driving system transmitting torque between a power source and a driving wheel with a determination reference value comprises an inference means (steps S201 to S208) for inferring that fluctuation of input torque from a power source side for the driving system is large and a determination reference value setting means (steps S305, S308) for setting the determination reference value to a value by which determination of a bad road is not easily satisfied when it is inferred that fluctuation of input torque is large more than a case where it is not inferred. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an apparatus for detecting a road surface state when a vehicle is traveling.

  The road surface on which the vehicle travels is not constant, such as unevenness or being slippery due to rain or snow, so the drive wheels momentarily lose grip and slip (slip) immediately after There may be a situation where the grip force is restored by touching the ground. Sliding drive wheels not only impair vehicle stability, but also boost the engine, reduce fuel consumption, and if the vehicle is equipped with a continuously variable transmission, May cause slippage in the transmission.

  The clamping pressure for clamping the torque transmission member in the continuously variable transmission may be a pressure determined based on the torque capacity to be transmitted. However, if the clamping pressure is higher than necessary, the power transmission efficiency of the continuously variable transmission is lowered, and the durability of the continuously variable transmission is lowered. Further, when the clamping pressure is set by hydraulic pressure, the power loss in the hydraulic pump increases, and as a result, the fuel consumption of the vehicle equipped with the continuously variable transmission deteriorates. Therefore, it is preferable that the clamping pressure in the continuously variable transmission is set as low as possible within a range in which excessive slip does not occur between the rotating member and the torque transmission member.

  If the above-mentioned clamping pressure or torque capacity in the continuously variable transmission is kept constant, the torque acting on the continuously variable transmission becomes excessively large, and the rotating member and torque transmitting member in the continuously variable transmission Excessive sliding may occur between the two. On the other hand, conventionally, a control device capable of performing control corresponding to the slip of the continuously variable transmission is known, and an example of the control device is described in Patent Document 1. In the vehicle described in Patent Document 1, engine torque is transmitted to drive wheels via a torque converter with a lock-up clutch, a forward / reverse switching device, a belt-type continuously variable transmission, a reduction gear device, and a differential gear device. It is configured to be. The belt type continuously variable transmission includes an input shaft and an output shaft, variable pulleys respectively provided on the input shaft and the output shaft, and a belt wound around these variable pulleys.

Further, the operation of the variable pulley is controlled by the hydraulic actuator, the belt winding diameter is adjusted, the gear ratio of the belt-type continuously variable transmission is controlled, and the clamping pressure on the belt is adjusted. Specifically, when the change width of the rotational acceleration of the drive wheel exceeds a predetermined criterion, the belt clamping pressure is temporarily increased. By such control, slipping and gripping of the driving wheels are repeated, and slipping of the belt is suppressed during a rough road traveling where a relatively large torque is transmitted from the driving wheel to the belt.
JP-A-4-285361

  According to the invention of Patent Document 1 described above, it is possible to prevent or avoid belt slip by increasing the pinching pressure in response to rough road traveling. However, the conditions of road surfaces including bad roads are various, and the state of torque change that causes belt slippage due to the road surface condition is not uniform. In some cases, the pinching pressure becomes relatively excessive, or on the contrary, the belt slip easily occurs due to shortage.

  For example, when driving on a so-called good road such as a flat automobile road, there is little change in vehicle speed and engine load, and there is almost no change in torque input from the road surface. It is preferable to reduce the margin width. On the other hand, on a road where acceleration and deceleration are performed relatively frequently, the change in torque acting on the continuously variable transmission is relatively large. Therefore, it is preferable to increase the so-called margin of the clamping pressure against the belt slip.

  In other words, the so-called margin of the clamping pressure is easy to cause belt slipping. Therefore, when the bad road determination for the increase control of the clamping pressure is uniformly performed, the determination of the bad road is delayed. There is a possibility that, even though there is a margin in the clamping pressure, the rough road determination is established and the clamping pressure is further increased.

  Further, the torque acting on the drive system such as a continuously variable transmission is not limited to the torque input from the drive wheel when traveling on a rough road as described above, for example, the change in the combustion state of the engine, the torque converter There may be fluctuations due to a change in the engagement state of the lock-up clutch or a torque from the power source side when the accelerator is turned ON / OFF. The torque fluctuation of the continuously variable transmission due to the torque fluctuation from the power source side is not as large as the torque fluctuation of the continuously variable transmission due to the torque fluctuation from the power source side, but is a criterion for determining the road surface condition. This has an effect on the magnitude of the detected value that is detected for comparison with the value, and may cause an erroneous determination of road surface condition determination.

  The present invention has been made paying attention to the above technical problem, and an object thereof is to provide a vehicle road surface state determination device that can prevent erroneous determination of road surface state determination and improve determination accuracy. It is.

  In order to achieve the above object, the invention according to claim 1 is based on a result of comparison between a predetermined detection value and a judgment reference value in a drive system that transmits torque between a power source and a drive wheel. In the vehicle road surface condition determination device that performs the determination, the prediction means that predicts that the fluctuation of the input torque from the power source side with respect to the drive system is large, and the prediction that the fluctuation of the input torque is large is not predicted. In some cases, the apparatus includes a determination reference value setting unit that sets the determination reference value to a value that is difficult to determine a rough road.

  According to a second aspect of the present invention, in the first aspect of the invention, the drive system includes a power transmission mechanism, and the determination reference value set by the determination reference value setting means and the predetermined detection value are A road surface state determination unit that determines a road surface state based on the road surface state, and a corresponding control unit that controls the power transmission mechanism based on a determination result by the road surface state determination unit. .

  According to the first aspect of the present invention, for example, torque fluctuation from the power source side that occurs when, for example, the combustion state of the engine, the engagement state of the lock-up clutch of the torque converter, or when the accelerator is turned ON / OFF is changed in advance. The judgment criterion that is predicted and set in that case is set to a criterion that makes it difficult to determine a rough road than the judgment criterion that is set when torque fluctuation from the power source is not predicted. As a result, it is possible to prevent erroneous determination of road surface condition determination and improve determination accuracy.

  Further, according to the invention of claim 2, when the presence or absence of occurrence of torque fluctuation from the power source side is predicted, and the road surface condition determination criterion is set according to the prediction result, the predetermined detection in the drive system is performed. The road surface condition is determined by comparing the value with the criterion. Then, based on the determination result, for example, the control of setting of the engagement pressure of the clutch provided as the line pressure of the power transmission mechanism of the vehicle or the torque fuse, or the clamping pressure control for increasing / decreasing the clamping pressure of the continuously variable transmission The corresponding control is executed. As a result, appropriate response control can be performed reflecting the road surface condition determination result, and the fuel efficiency of the vehicle and the durability of the continuously variable transmission can be improved.

  Next, the present invention will be described based on specific examples. First of all, a vehicle and its control system as objects of the present invention will be described. FIG. 4 schematically shows a drive system of a vehicle on which a belt type continuously variable transmission 1 is mounted. Is connected to a power source 5 via a forward / reverse switching mechanism 2 and a fluid transmission mechanism 4 with a lock-up clutch 3.

  The power source 5 is composed of an internal combustion engine, or an internal combustion engine and an electric motor, or an electric motor. In the following description, the power source 5 is referred to as the engine 5. The fluid transmission mechanism 4 has, for example, a configuration similar to that of a conventional torque converter, and includes a pump impeller rotated by the engine 5, a turbine runner disposed so as to face the pump impeller, and a stator disposed therebetween. The turbine runner is rotated by supplying a spiral flow of fluid generated by the pump impeller to the turbine runner, and the torque is transmitted.

  In such torque transmission through the fluid, inevitable slip occurs between the pump impeller and the turbine runner, and this causes a reduction in power transmission efficiency. Therefore, the input member such as the pump impeller and the turbine runner A lock-up clutch 3 that directly connects an output side member such as the above is provided. The lock-up clutch 3 is configured to be controlled by hydraulic pressure, and is controlled to a fully engaged state, a fully released state, and a slip state that is an intermediate state between them, and the slip rotation speed can be appropriately controlled. It has become.

  The forward / reverse switching mechanism 2 is a mechanism that is employed when the rotational direction of the engine 5 is limited to one direction, and outputs the input torque as it is or reversely outputs it. It is configured. In the example shown in FIG. 4, a double pinion type planetary gear mechanism is employed as the forward / reverse switching mechanism 2. That is, a ring gear 7 is arranged concentrically with the sun gear 6, and a pinion gear 8 meshed with the sun gear 6 and the pinion gear 8 and another pinion gear 9 meshed with the ring gear 7 are arranged between the sun gear 6 and the ring gear 7. The pinion gears 8 and 9 are held by the carrier 10 so as to rotate and revolve freely. A forward clutch 11 that integrally couples the two rotating elements (specifically, the sun gear 6 and the carrier 10) is provided, and the direction of the torque that is output by selectively fixing the ring gear 7 There is provided a reverse brake 12 that reverses.

  The continuously variable transmission 1 has the same configuration as a conventionally known belt-type continuously variable transmission, and each of a driving pulley 13 and a driven pulley 14 arranged in parallel to each other includes a fixed sheave, a hydraulic type The movable sheave is moved back and forth in the axial direction by the actuators 15 and 16. Therefore, the groove width of each pulley 13 and 14 is changed by moving the movable sheave in the axial direction, and accordingly, the winding radius of the belt 17 wound around each pulley 13 and 14 (the effective diameter of the pulleys 13 and 14). ) Changes continuously, and the gear ratio changes steplessly. The drive pulley 13 is connected to a carrier 10 that is an output element in the forward / reverse switching mechanism 2.

  The hydraulic actuator 16 in the driven pulley 14 is supplied with hydraulic pressure (line pressure or its correction pressure) according to the torque input to the continuously variable transmission 1 via a hydraulic pump and a hydraulic control device (not shown). Yes. Therefore, each sheave in the driven pulley 14 holds the belt 17 so that tension is applied to the belt 17, and a holding pressure (contact pressure) between the pulleys 13, 14 and the belt 17 is ensured. . On the other hand, the hydraulic actuator 15 in the drive pulley 13 is supplied with pressure oil corresponding to the speed ratio to be set, and is set to a groove width (effective diameter) corresponding to the target speed ratio. .

  The driven pulley 14 is connected to a differential 19 through a gear pair 18, and torque is output from the differential 19 to driving wheels 20. Therefore, in the above drive mechanism, the lockup clutch 3 and the continuously variable transmission 1 are arranged in series between the engine 5 and the drive wheels 20.

  Various sensors are provided in order to detect the operation state (running state) of the vehicle on which the continuously variable transmission 1 and the engine 5 are mounted. That is, a turbine rotation speed sensor 21 that detects an input rotation speed (rotation speed of the turbine runner) to the continuously variable transmission 1 and outputs a signal, and an input rotation speed that detects the rotation speed of the drive pulley 13 and outputs a signal. A sensor 22, an output rotation speed sensor 23 that detects the rotation speed of the driven pulley 14 and outputs a signal, and a hydraulic pressure sensor 24 that detects the pressure of the hydraulic actuator 16 on the driven pulley 14 side for setting the belt clamping pressure are provided. ing. Although not specifically shown, an accelerator opening sensor that detects a depression amount of the accelerator pedal and outputs a signal, a throttle opening sensor that detects a throttle valve opening and outputs a signal, and a brake pedal are depressed. A brake sensor or the like that outputs a signal in case is provided.

  A transmission is used to control the engagement / release of the forward clutch 11 and the reverse brake 12, the control of the clamping force of the belt 17, the control of the transmission ratio, and the control of the lockup clutch 3. An electronic control device (CVT-ECU) 25 is provided. The electronic control unit 25 is configured mainly by a microcomputer as an example, performs calculations according to a predetermined program based on input data and data stored in advance, and various states such as forward, reverse, or neutral, Further, it is configured to execute control such as setting of a required clamping pressure, setting of a gear ratio, engagement / release of the lock-up clutch 3, and slip rotation speed.

  Here, an example of data (signal) input to the transmission electronic control unit 25 is as follows: a signal of the input rotation speed (input rotation speed) Nin of the continuously variable transmission 1 and an output of the continuously variable transmission 1. A signal of the rotation speed (output rotation speed) No is input from the corresponding sensor. An engine electronic control unit (E / G-ECU) 26 for controlling the engine 5 receives a signal of an engine speed Ne, an engine (E / G) load signal, a throttle opening signal, an accelerator pedal (not shown). )), The accelerator opening signal is input.

  According to the continuously variable transmission 1, the engine speed, which is the input speed, can be controlled steplessly (in other words, continuously), so that the fuel efficiency of a vehicle equipped with the engine speed can be improved. For example, the target driving force is obtained based on the required driving amount represented by the accelerator opening and the vehicle speed, and the target output necessary to obtain the target driving force is obtained based on the target driving force and the vehicle speed. The engine speed for obtaining the target output with the optimum fuel consumption is obtained based on a map prepared in advance, and the gear ratio is controlled so as to be the engine speed.

  In order not to impair such an improvement in fuel consumption, the power transmission efficiency in the continuously variable transmission 1 is controlled to a good state. Specifically, the torque capacity of the continuously variable transmission 1, that is, the belt clamping pressure, can transmit the target torque determined based on the engine torque, and the belt clamping pressure is as low as possible without causing the belt 17 to slip. It is controlled to become. For example, the belt clamping pressure controls the continuously variable transmission 1 in a so-called unsteady traveling state such as when acceleration / deceleration is performed relatively frequently or when traveling on a rough road with uneven or uneven road surfaces. It is set to a relatively high pressure such as the line pressure that is the total source pressure in the hydraulic system or its correction pressure.

  On the other hand, in steady running conditions such as running on a flat road at a vehicle speed of a certain level or a quasi-steady running condition equivalent thereto, the lowest pressure that can transmit input torque without slipping, that is, the limit In order to detect the pressure, the belt clamping pressure is gradually reduced. The belt clamping pressure is set to a belt clamping pressure obtained by adding a predetermined safety factor or a pressure for setting a margin transmission torque for slipping to the detected limit clamping pressure.

  When the vehicle is traveling, the torque output from the engine 5, the torque input from the drive wheels 20, the gear ratio, and the like vary variously based on the gradient of the traveling path, unevenness, acceleration / deceleration operation, and the like. If the belt clamping pressure is set in response to such a change, the belt clamping pressure is unnecessarily increased in order to prevent excessive slip in the continuously variable transmission 1 due to a sudden increase in input torque or road disturbance. The situation can be avoided.

  However, the torque acting on the continuously variable transmission 1 includes, in addition to the sudden increase in input torque and road surface disturbance as described above, torque fluctuations that occur when the combustion state of the engine 5 is switched, and whether the accelerator is on / off. Slightly temporarily due to torque fluctuations caused by the effects of inertia torque and gear backlash when switching operations, or torque fluctuations that occur when the lockup clutch 3 provided in the fluid transmission mechanism 4 is fully engaged. fluctuate. At this time, if these torque fluctuations are mistaken as torque fluctuations caused by road surface disturbance from the drive wheel 20 side, the belt clamping pressure may be set unnecessarily high.

  Therefore, the road surface condition determination apparatus according to the present invention predicts a change in torque input from the power source side to the drive system, and appropriately selects a determination criterion for road surface condition determination when the torque change is predicted. The road surface state is determined, and appropriate response control is performed based on the road surface state determination result. A specific example of the control will be described below.

  1 and 2 are flowcharts showing an example. In FIG. 1, first, an output shaft rotational speed Nout (i) is measured as an index value indicating a change in the operating state of the continuously variable transmission 1, and a plurality of low-pass filter processes having different cutoff frequencies are applied to the measured value. Thus, the filter processing values f1 (i) and f2 (i) are calculated (step S101). Since the actual measured value of the output shaft rotational speed Nout (i) of the continuously variable transmission 1 includes a vibration component due to noise and a tilt component due to fluctuations, by passing through a plurality of filters in this way, A vibration component, an inclination component, etc. can be removed, and the comparison with the threshold value for road surface condition determination mentioned later can be made easy.

When the filter processing values f1 (i) and f2 (i) are calculated in step S101, their change amounts Δf1 (i) and Δf2 (i) are calculated, and a difference D that is the difference between these change amounts is calculated. Is calculated (step S102). That is, the filter processing values f1 (i) and f2 (i) calculated from the current output shaft rotational speed Nout (i) and the filter processing value f1 ( i-1) and f2 (i-1), the changes Δf1 (i) and Δf2 (i) and the difference D are respectively
Δf1 (i) = f1 (i) −f1 (i−1)
Δf2 (i) = f2 (i) −f2 (i−1)
D = Δf1 (i) −Δf2 (i)
Can be calculated as

  Subsequently, the process proceeds to step S103, where it is determined whether or not there is a variation factor of the input torque to the continuously variable transmission 1, such as switching between the combustion mode of the engine 5 and accelerator ON / OFF, and determination of the road surface state is performed according to the determination result. Predetermined control for changing the reference is executed. The predetermined control will be described with reference to a flowchart of another routine shown in FIG.

  In FIG. 2, it is first determined whether or not a combustion mode switching command for the engine 5 has been output (step S201). The combustion mode switching of the engine 5 refers to the combustion state of the engine 5 in accordance with the output torque of the engine 5, for example, the combustion state (so-called stoichiometric) region in the vicinity of the stoichiometric air-fuel ratio, and the ratio of fuel to the stoichiometric air-fuel ratio. This is to switch between a lean combustion state (so-called lean burn) in which the engine 5 is combusted with a small air-fuel ratio. As described above, the fuel consumption can be improved by appropriately switching the combustion state of the engine 5 between the stoichiometric region and the lean burn region, that is, the combustion mode, according to the output torque, and the combustion mode is improved. When switching, a slight torque fluctuation occurs temporarily in the output torque of the engine 5.

  The variation of the output torque of the engine 5 becomes a variation factor of the input torque of the continuously variable transmission 1, and the difference calculated above based on the change of the operation state due to the change of the operation state of the continuously variable transmission 1. There is a possibility that D exceeds the determination threshold value of “bad road” and erroneously determines that there is a disturbance from the output side during traveling on “bad road”. Therefore, in this step S201, it is determined whether or not there is a command for switching the combustion mode of the engine 5, and as described later, the road surface condition determination threshold is changed in accordance with the frequency of occurrence, thereby causing the torque fluctuation as described above. It is possible to prevent misjudgment of the road surface condition due to.

  If a negative determination is made in step S201 because the combustion mode switching command of the engine 5 has not been output, the process proceeds to step S202, where a switching command from the accelerator OFF to the accelerator ON or from the accelerator ON to the accelerator OFF is issued. It is determined whether it has been output. In other words, it is determined whether or not the accelerator pedal has been released or whether the accelerator pedal has been released.

  When a command for switching from accelerator OFF to accelerator ON or from accelerator ON to accelerator OFF is output, the output torque of the engine 5 increases or decreases based on the command, but the inertia torque generated when the torque changes Since there is a backlash between the gears of each part of the drive system, the tooth surfaces of the gears that mesh with each other with a gap corresponding to the backlash collide with each other, and a play caused by so-called gear play occurs instantaneously. The impact due to the rattling of the gear becomes a variation factor of the input torque of the continuously variable transmission 1 and changes the operating state of the continuously variable transmission 1 in the same manner as when the combustion mode of the engine 5 is switched. There is a possibility that it is erroneously determined that the vehicle is traveling on a “bad road” or that there is a disturbance from the output side.

  Therefore, as in step S201 described above, in step S202, it is determined whether or not there is a command to switch from accelerator OFF to accelerator ON, or from accelerator ON to accelerator OFF, and the road surface condition is determined according to the frequency of occurrence as described later. By changing the determination threshold, it is possible to prevent erroneous determination of the road surface state due to the occurrence of torque fluctuation as described above.

  If a negative determination is made in step S202 because the command for switching from the accelerator OFF to the accelerator ON or the accelerator ON to the accelerator OFF is not output, the process proceeds to step S203, where the fluid transmission mechanism 4 is provided. The presence / absence of an engagement control command for the lockup clutch 3 is determined. The lock-up clutch 3 is appropriately controlled to a fully engaged state, a fully released state, and a slip state that is an intermediate state between them. A slight shock occurs at the moment of being played. This slight shock becomes a variation factor of the input torque of the continuously variable transmission 1 as in the case of switching the combustion mode of the engine 5 and switching the accelerator ON / OFF, and the operating state of the continuously variable transmission 1 is changed. By changing, there is a possibility that it is erroneously determined that the vehicle is traveling on a “bad road” or that there is a disturbance from the output side.

  Therefore, similarly to the above-described step S201 and step S202, it is determined in this step S203 whether or not the lockup clutch 3 is under engagement control, and the road surface condition is determined in accordance with the frequency of occurrence as described later. By changing the threshold value, it is possible to prevent erroneous determination of the road surface state due to the occurrence of torque fluctuation as described above.

  If a positive determination is made in any of the above steps S201 to S203, the process proceeds to step S204, where the torque fluctuation occurrence counter C is reset to zero. In other words, when a command for switching the combustion mode of the engine 5 is output, or when a command for switching from accelerator OFF to accelerator ON or accelerator ON to accelerator OFF is output, or the lock-up clutch 3 is engaged. If a torque fluctuation factor occurs such as in the case of, the process proceeds to step S204, where the torque fluctuation occurrence counter C is reset to zero. Thereafter, the process proceeds to step S205.

  Further, even when a negative determination is made in step S203 because the lockup clutch 3 is not under engagement control, the process proceeds to step S205, and the torque fluctuation occurrence counter C is incremented.

  Subsequently, it is determined whether or not the torque fluctuation occurrence counter C is greater than a predetermined value c1 (step S206). If the torque fluctuation counter C is greater than the predetermined value c1, if the determination in step S206 is affirmative, that is, if the occurrence frequency of the torque fluctuation factor is low, the process proceeds to step S207 and the torque fluctuation occurrence flag F is “0”. Set to On the other hand, if the torque fluctuation counter C is less than or equal to the predetermined value c1, a negative determination is made in step S206, that is, if the frequency of occurrence of torque fluctuation factors is high, the process proceeds to step S208, where torque fluctuation occurs. The flag F is set to “1”.

  This flag F is a torque fluctuation occurrence flag that is set to “0” when the torque fluctuation occurrence counter C is greater than the predetermined value c1, and is set to “1” when it is equal to or smaller than the predetermined value c1. That is, the torque fluctuation occurrence flag F is a flag that is set to “0” when the frequency of occurrence of torque fluctuation is low and is set to “1” when the frequency of occurrence of torque fluctuation is high.

  Thereafter, the routine is exited, and the process proceeds to step S104 in the flowchart of FIG. 1 or to step S306 in the flowchart of another specific example of the present invention shown in FIG.

  Returning to step S104 of the flowchart of FIG. 1, the torque fluctuation occurrence flag F is determined. When the torque fluctuation occurrence flag F is “0”, that is, when the torque fluctuation factor frequently occurs exceeding a predetermined value, the process proceeds to step S105 and the absolute value of the difference D calculated in the above-described step S102. Is determined to be greater than a predetermined threshold value d1 as a road surface condition determination criterion. This threshold value d1 in this control example is a reference value determined to be a value smaller than a threshold value d2 to be described later. In other words, compared to the threshold value d2 of the road surface condition determination reference, the road surface condition determination reference Is a reference value set so that the determination of “bad road” is more easily established.

  If the negative value of the difference D is determined to be negative in step S105 because the absolute value of the difference D is equal to or less than the threshold value d1, that is, if the absolute value of the difference D does not exceed the threshold value d1 of the road surface condition determination criterion, the road surface that is running The state is determined to be a “good road” in which the road surface is flat and has little unevenness on the road surface, and there is no rainfall or snowfall. The process proceeds to step S106, and the normal clamping pressure control is executed. Thereafter, this routine is once terminated.

  On the other hand, if the absolute value of the difference D is affirmatively determined in step S105 because it is greater than the threshold value d1, that is, if the absolute value of the difference D exceeds the road surface condition criterion threshold d1, The road surface condition is determined as a “bad road” that has a steep slope or slope, a large unevenness or an obstacle, or is slippery due to rain or snow, etc. Proceeding to S107, in order to prevent an excessive slip from occurring in the continuously variable transmission 1 due to an influence of road surface disturbance caused by traveling on a “bad road”, a clamping pressure increase control for increasing the clamping pressure hydraulic pressure is executed. . Thereafter, this routine is once terminated.

  On the other hand, if the torque fluctuation occurrence flag F determined in step S104 is “1”, that is, if the torque fluctuation factor has not occurred to the extent that it exceeds the predetermined value, the process proceeds to step S108 and is calculated in step S102 described above. It is determined whether or not the absolute value of the difference D is greater than a predetermined threshold value d2 as a road surface condition determination criterion. As described above, the threshold value d2 is set to be larger than the threshold value d1, that is, compared to the threshold value d1, the threshold value d2 is set so that the determination of “bad road” is less likely to be established. This is the reference value.

  Like these threshold values d1 and d2, by providing a plurality of determination criteria of different sizes, which are different in the ease of establishment of the “bad road” determination, an erroneous determination is made when determining the road surface condition. In accordance with the frequency of occurrence of torque fluctuation, which is a cause of the road surface, it is possible to make a determination based on an appropriate road surface condition determination criterion, thereby preventing erroneous determination of the road surface condition determination and improving the determination accuracy.

  If the negative value of the difference D is determined to be negative in step S108 because the absolute value of the difference D is less than or equal to the threshold d2, that is, if the absolute value of the difference D does not exceed the threshold d2 of the road surface condition criterion, the road surface that is running The state is determined to be the above-mentioned “good road” or “semi-good road”, which is a state equivalent to the above-mentioned “good road”, and the process proceeds to step S109 to execute the normal clamping pressure control. Thereafter, this routine is once terminated.

  On the other hand, if the absolute value of the difference D is determined to be affirmative in step S108 because it is larger than the threshold value d2, that is, if the absolute value of the difference D exceeds the threshold value d2 of the road surface condition determination criterion, As in the case of negative determination in step S105, the traveling road surface state is determined to be “bad road”, and the process proceeds to step S110, and due to the influence of road surface disturbance caused by traveling on “bad road”, etc. In order to prevent an excessive slip from occurring in the continuously variable transmission 1, a clamping pressure up control is performed to increase the clamping pressure hydraulic pressure. Thereafter, this routine is once terminated.

  It should be noted that the threshold value d1 and the threshold value d2, which are used as the road surface condition determination criteria in each of the above steps S105 and S108, are calculated based on the running state of the vehicle, in addition to being set or stored in advance. It can also be a value obtained.

  As described above, according to the control device according to the present invention configured to execute the control shown in FIGS. 1 and 2 described above, it becomes a fluctuation factor of the input torque to the continuously variable transmission 1, and an error occurs when the road surface condition is determined. The presence / absence of a control command such as switching of the combustion mode of the engine 5, switching of the accelerator ON / OFF, or engagement of the lock-up clutch 3 that may cause the determination is detected and determined. Occurrence is expected. Depending on the predicted occurrence frequency of the torque fluctuation factor, the road surface condition determination criterion is appropriately selected from a plurality of determination criteria having different sizes, that is, different ease of establishment of the “bad road” determination. Is set. And pinching pressure control is performed according to the road surface state judged by the road surface state determination criterion. As a result, it is possible to prevent erroneous determination of road surface condition determination and improve determination accuracy. Moreover, since appropriate clamping pressure control can be executed based on the determination result of the road surface state determined with high accuracy, it is possible to prevent or suppress the clamping pressure from being set unnecessarily high, or Excessive slippage in the continuously variable transmission 1 due to the lack of can be prevented or suppressed.

  Next, another specific example of the present invention will be described. In the specific example described above, occurrence of a torque fluctuation factor is predicted, road surface condition determination criteria are appropriately set, and sandwiching pressure control is performed reflecting the road surface state determined based on the determination criteria. However, in the present invention, instead of this, it is possible to reflect the prediction result of the torque fluctuation factor so that appropriate clamping pressure reduction control and engagement control of the lockup clutch 3 are executed.

  FIG. 3 is a flowchart for explaining the example. First, it is determined whether or not a precondition for control is satisfied (step S301). The preconditions for control here are, for example, that there are no abnormalities in various sensors, and that the shift range of the transmission is a drive range.

  If it is determined negative in step S301 because the control preconditions are not satisfied, the process proceeds to step S312 to execute normal clamping pressure control and to control engagement of the lockup clutch 3. Is executed. Thereafter, this routine is once terminated.

  In addition, if the control precondition is satisfied and the determination is affirmative in step S301, the process proceeds to step S302, where the output shaft rotational speed Nout (i) is measured, and the measured value is the cutoff frequency. Filter processing values f1 (i) and f2 (i) are calculated by applying a plurality of low-pass filter processings different from each other. In step S303, Δf1 (i) and Δf2 (i), which are changes from the previous values of the filter processing values f1 (i) and f2 (i), and a difference D that is a difference between the changes are calculated. Is done. Since the control contents of steps S302 and S303 are the same as the control contents of steps S101 and S102 in the flowchart of FIG. 1, the detailed description is omitted.

  When the difference D in the amount of change of each filter processing value is calculated in step S303, the process proceeds to step S304, and it is determined whether or not the clamping pressure reduction condition is satisfied. In order to detect the limit clamping pressure by reducing the clamping pressure, the torque acting on the continuously variable transmission 1 needs to be stable. Therefore, the clamping pressure reduction condition here is, for example, traveling on a flat good road within a predetermined vehicle speed range and a predetermined acceleration range, in other words, traveling on a flat good road in a steady state or a quasi-steady state. And so on.

  If the negative pressure reduction condition is not satisfied, and if a negative determination is made in step S304, the process proceeds to step S312 as in the negative determination in step S301 described above, and the normal normal pressure is determined. The control is executed and the engagement control of the lockup clutch 3 is executed. Thereafter, this routine is once terminated.

  On the other hand, if a positive determination is made in step S304 because the holding pressure reduction condition is satisfied, the process proceeds to step S305, and predetermined control is executed. This predetermined control has the same contents as the predetermined control in step S103 (that is, the flowchart of FIG. 2) in the flowchart of FIG.

  When the predetermined control is executed in step S305, the process proceeds to step S306, and it is determined whether or not the absolute value of the difference D calculated in step S303 described above is larger than a predetermined threshold value d1 as a road surface condition determination criterion. Is done. In this control example, the threshold value d1 and a threshold value d2 described later are the same as the threshold values d1 and d2 in the control example of the flowchart of FIG. 1 described above, and compared with the threshold value d1 of the road surface condition determination criterion, This is a reference value in which the reference threshold value d2 is set so that the “bad road” determination is less likely to be established.

  If the negative value of the difference D is determined to be negative in step S306 because the absolute value of the difference D is equal to or less than the threshold value d1, that is, if the absolute value of the difference D does not exceed the threshold value d1 of the road surface condition determination criterion, the road surface that is running The state is determined to be “good road”, the process proceeds to step S308, and the clamping pressure reduction control is executed, and the lockup clutch 3 is controlled to function as a torque fuse for the continuously variable transmission 1. 3 torque fuse control is executed. Thereafter, this routine is once terminated.

  Here, the torque fuse control of the lock-up clutch 3 is a control for limiting the torque acting on the continuously variable transmission 1 by a clutch arranged in series with the continuously variable transmission 1. This is control for setting the transmission torque capacity of the lockup clutch 3, that is, the engagement pressure so that the lockup clutch 3 slips before the continuously variable transmission 1 when the applied torque increases. In other words, it is a control for setting the margin of the transmission torque capacity until the slip occurs so that the lockup clutch 3 reduces the margin of the continuously variable transmission 1.

  On the other hand, if the absolute value of the difference D is affirmatively determined in step S306 because it is greater than the threshold value d1, that is, if the absolute value of the difference D exceeds the road surface condition criterion threshold d1, the process proceeds to step S307. The torque fluctuation occurrence flag F is determined.

  When the torque fluctuation generation flag F determined in step S307 is “0”, that is, when the torque fluctuation factor frequently occurs exceeding a predetermined value, the process proceeds to step S309, and the normal clamping pressure control is performed. Is executed, and the torque fuse control of the lock-up clutch 3 is finished, and standby control waiting for the next control command is executed. Thereafter, this routine is once terminated.

  On the other hand, if the torque fluctuation generation flag F determined in step S307 is “1”, that is, if the torque fluctuation factor does not occur to a degree exceeding the predetermined value, the process proceeds to step S310, and in step S303 described above. It is determined whether or not the calculated absolute value of the difference D is larger than a predetermined threshold d2 as a road surface condition determination criterion.

  If the absolute value of the difference D is determined to be negative in this step S310 because it is less than or equal to the threshold d2, that is, if the absolute value of the difference D does not exceed the threshold d2 of the road surface condition determination criterion, the process proceeds to step S311. The normal clamping pressure control, or when the clamping pressure has been reduced, the control to return to the normal clamping pressure is executed. Thereafter, this routine is once terminated.

  On the other hand, when an affirmative determination is made in step S310 because the absolute value of the difference D is larger than the threshold value d2, that is, when the absolute value of the difference D exceeds the road surface condition determination reference threshold value d2, As in the case where the torque fluctuation occurrence flag F determined in step S307 is “0”, the process proceeds to step S309, and the normal clamping pressure control is executed and the torque fuse control of the lockup clutch 3 is performed. Is completed, and standby control waiting for the next control command is executed. Thereafter, this routine is once terminated.

  As described above, according to the control device according to the present invention configured to execute the control shown in FIG. 3 above, when the clamping pressure reduction condition of the clamping pressure reduction control for detecting the limit clamping pressure is satisfied, the continuously variable transmission is performed. Switching of the combustion mode of the engine 5, switching of the accelerator ON / OFF, or engagement of the lock-up clutch 3, which may cause fluctuations in the input torque to the machine 1 and cause erroneous determination when determining the road surface condition The presence / absence of a control command such as a match is detected and judged, and the occurrence of a torque fluctuation factor is predicted. Based on the predicted occurrence frequency of the torque fluctuation factor and a plurality of road surface condition determination criteria having different magnitudes, that is, different ease of establishment of the “bad road” determination, The return control of the clamping force and the torque fuse control of the lockup clutch 3 or the end standby control of the torque fuse control are executed. As a result, it is possible to perform appropriate pinching pressure reduction control or torque fuse control of the lock-up clutch 3 based on the determination result of the road surface state that is determined with high accuracy while preventing erroneous determination.

  Here, the relationship between each of the above specific examples and the present invention will be briefly described. The functional means in steps S201 to S208 described above correspond to the predicting means in the invention of claim 1, and each of steps S105 and S108 is performed. The functional means corresponds to the judgment reference value setting means in the invention of claim 1. The functional means in steps S105 and S108 correspond to the road surface condition judging means in the invention of claim 2, and the functional means in steps S106 to S110 are correspondence control means in the invention of claim 2. It corresponds to.

  Note that the present invention is not limited to the above specific example, and can be applied to a control device for a traction type continuously variable transmission in addition to a belt type continuously variable transmission. In the above specific example, the control example for increasing / decreasing the clamping pressure of the continuously variable transmission has been described as corresponding to the corresponding control means of the invention of claim 2, but is executed by this corresponding control means. The response control is control that can obtain the effect or improve the effect by being controlled according to the road surface state determined by the road surface state determining means of the present invention. Specifically, for example, the present invention can be applied to control for setting the line pressure in the drive system according to the road surface condition, or control for changing the strength of the vehicle suspension according to the road surface condition.

It is a flowchart for demonstrating an example of control by the control apparatus of this invention. It is a flowchart for demonstrating the part regarding predetermined control of an example of control by the control apparatus of this invention. It is a flowchart for demonstrating the other control example by the control apparatus of this invention. It is a figure which shows typically an example of the drive system containing the continuously variable transmission made into object by this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Continuously variable transmission, 3 ... Lock-up clutch, 5 ... Engine (power source), 13 ... Drive pulley, 14 ... Drive pulley, 15, 16 ... Hydraulic actuator, 17 ... Belt, 20 ... Drive wheel, 25 ... Shift Electronic control unit for machine (CVT-ECU).

Claims (2)

In a vehicle road surface state determination device that determines a road surface state based on a comparison result between a predetermined detection value and a determination reference value in a drive system that transmits torque between a power source and a drive wheel,
A predicting means for predicting that the fluctuation of the input torque from the power source side to the drive system is large;
When it is predicted that the fluctuation of the input torque is large, it is provided with a determination reference value setting unit that sets the determination reference value to a value that makes it difficult to determine a rough road as compared with a case where the fluctuation is not predicted. Vehicle road surface condition determination device. The drive system includes a power transmission mechanism,
Road surface condition determining means for determining a road surface condition based on the determination reference value set by the determination reference value setting means and the predetermined detection value;
2. The vehicle road surface state determination device according to claim 1, further comprising: a corresponding control unit that controls the power transmission mechanism based on a determination result by the road surface state determination unit.

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