JP2015218660A - Engine overspeed prevention control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably prevent generation of overspeed by curbing deterioration of convergence with an upper limit engine rotation speed due to a change in a traveling state of a vehicle.SOLUTION: An overspeed prevention control device prevents overspeed of an engine mounted on a vehicle through torque control of the engine. The overspeed prevention control device has a control section which obtains required torque to make an engine rotate at an upper limit engine rotation speed and controls engine torque on the basis of the required torque when an engine rotation speed is not less than a limited rotation speed to execute the torque control. The control section obtains required torque on the basis of a travel resistance value of the vehicle.

Description

  The present invention relates to an engine overspeed prevention control apparatus for preventing engine overspeed.

  Conventionally, when a gasoline engine or the like exceeds an upper limit rotational speed and is over-rotated, a fuel cut control that temporarily stops fuel injection is executed to limit the engine torque.

  However, in the torque limit by the fuel cut control, the torque is greatly reduced by stopping the fuel injection. Therefore, it is necessary to control the engine speed by repeatedly stopping and restarting the fuel injection. A change in acceleration occurred in the front-rear direction, which could give the driver a sense of discomfort.

  On the other hand, for example, as described in Patent Document 1, when the limit torque is set to decrease in accordance with the increase in the engine rotation speed and the actual engine rotation speed becomes higher than the target engine rotation speed, A technique for preventing an excessive rotation by preventing an increase in engine rotation speed based on a limit torque is known.

JP 2004-245191 A

  According to the technique of Patent Document 1, since the limit torque is set based on the increase in engine rotation speed, when the vehicle running state changes and the engine rotation speed changes, the change causes the upper limit rotation speed. Inconveniences such as deterioration of convergence and over-rotation.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an engine overspeed prevention control device that prevents deterioration of convergence to an upper limit engine speed due to a change in the running state of a vehicle and stably prevents the occurrence of overspeed. To do.

  The present invention relates to an overspeed prevention control device that prevents overspeed of an engine by limiting torque for an engine mounted on a vehicle, and obtains a limit request torque for causing the engine speed to coincide with an upper limit engine speed. When the engine speed becomes equal to or higher than the limit speed for executing the torque limitation, the engine has a control unit that controls the engine torque based on the limit request torque, and the control unit is a running resistance of the vehicle The limit request torque is obtained based on the value.

  According to the present invention, it is possible to prevent deterioration of convergence to the upper limit engine speed due to a change in the running state of the vehicle, and to prevent the occurrence of overspeed stably.

FIG. 1 is a block diagram showing a simplified configuration of an engine overspeed prevention control device according to an embodiment of the present invention and some devices electrically connected thereto. FIG. 2 is a diagram showing an example of an engine torque map used in the engine overspeed prevention control apparatus according to the embodiment of the present invention. FIG. 3 is a diagram illustrating an example of a map used by the engine overspeed prevention control apparatus according to the embodiment of the present invention to calculate the torque limit control execution engine speed. FIG. 4 is a time chart for explaining the behavior of each controlled object when torque limit control is started by the engine overspeed prevention control device according to the embodiment of the present invention. ) Is the vehicle speed, (b) is the engine speed, (c) is the ignition timing, (d) is the throttle opening and intake air amount, (e) is the engine torque, and (f) is the vehicle driving force and travel. Regarding resistance. FIG. 5 is a diagram showing an example of a flowchart of success / failure determination of the torque limit control execution condition in the engine overspeed prevention control device according to the embodiment of the present invention. FIG. 6 is a diagram showing an example of a flowchart of torque limit control execution control after determination of success or failure of the torque limit control execution condition in the engine overspeed prevention control device according to the embodiment of the present invention. FIG. 7 is a diagram showing an example of a flowchart for executing the torque limiting method executed in the control flowchart after the determination of success or failure of the torque limiting control execution condition shown in FIG.

  Hereinafter, an engine overspeed prevention control apparatus according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 7.

  FIG. 1 is a block diagram of a control unit 1 that functions as an engine overspeed prevention control apparatus according to an embodiment of the present invention. The control unit 1 is electrically connected to a sensor unit 10 that supplies a signal indicating a sensor detection value, an input value, or a set value to the control unit 1 and an engine 100 that receives a control signal from the control unit 1. Yes.

  The control unit 1 is connected to a memory 180 for storing data temporarily or over a certain period.

  The sensor unit 10 includes a tire condition input device 11, a G sensor 12, a navigation system 13, an upper limit engine speed setting device 14, a tire moving radius input device 15, a gear position detection device 16, a speed sensor 17, a vehicle weight detection device 18, A throttle opening sensor 110 and a crank angle sensor 120 are provided.

  The tire condition input device 11 is a device for inputting a value representing, for example, a tire type or air pressure. The G sensor 12 is a device that outputs signals representing acceleration and deceleration acting on the vehicle. The navigation system 13 is a device that outputs signals representing road conditions and the current position of a vehicle based on data from, for example, GPS (Global Positioning System).

  The upper limit engine speed setting device 14 of the sensor unit 10 is a device for setting and inputting the upper limit engine speed. The upper limit engine speed is an arbitrary engine speed among the engine speeds including the maximum engine speed at which overspeed will occur and the engine speed smaller than this and the engine speed closer to this. . For example, the maximum engine speed may be set as an example of the upper limit engine speed.

  The tire dynamic radius input device 15 is a device for inputting a value representing the tire dynamic load radius. The gear stage detection device 16 is a device for detecting a gear stage of the transmission and outputting a signal representing the gear ratio of the gear stage.

  The speed sensor 17 of the sensor unit 10 is a device for detecting the vehicle speed. The vehicle weight detection device 18 is a device for detecting the vehicle weight. The throttle opening sensor 110 is a device that outputs a signal indicating the opening of the throttle valve. The crank angle sensor 120 is a device that outputs a signal representing the crank angle.

  In FIG. 1, a signal indicated by a broken line is output from some devices of the sensor unit 10 toward the control unit 1. If the values output from these devices are stored in advance in the memory 180, for example, and can be read out as necessary, these devices can be omitted.

  For example, the engine 100 performs a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke while the piston makes two reciprocations in the cylinder, and performs four cycles of ignition during the compression stroke and the expansion stroke. And includes an ignition coil 130, an injector 140, a throttle valve 150, an exhaust valve 160, and an intake valve 170.

  The control unit 1 includes a road surface gradient detection device 20, a maximum speed calculation device 30, a driving force calculation device 40, a propulsion force calculation device 50, an engine torque calculation device 60, a travel resistance calculation device 70, a limit request torque calculation device 80, and a torque limit. A control device 90 is provided.

  The running resistance calculation device 70 includes a rolling resistance estimation device 71, a gradient resistance calculation device 72, and an air resistance estimation device 73.

  A G sensor 12 and a navigation system 13 are electrically connected to the road surface gradient detection device 20, and a signal indicating acceleration or deceleration from the G sensor 12, and road information and the current position of the vehicle are expressed from the navigation system 13. Signal. The road surface gradient detection device 20 detects the road surface gradient on which the vehicle is traveling from these signals and outputs a signal representing the road surface gradient to the travel resistance calculation device 70.

  The maximum speed calculation device 30 is electrically connected to an upper limit engine speed setting device 14, a tire moving radius input device 15 and a gear position detection device 16, and the upper limit engine speed setting device 14 sets the upper limit set. A signal representing the engine speed, a signal representing the tire dynamic load radius from the tire dynamic radius input device 15, and a signal representing the gear ratio at the detected gear position of the transmission are input from the gear speed detection device 16.

  The maximum speed calculation device 30 calculates the maximum vehicle speed from these signals and outputs a signal representing the maximum vehicle speed to the running resistance calculation device 70.

  The engine torque calculation device 60 is electrically connected to a throttle opening sensor 110 and a crank angle sensor 120 of the sensor unit 10. A signal indicating the opening of the throttle valve from the throttle opening sensor 110, and a crank angle sensor From 120, a signal indicating the detected crank angle is input. The engine torque calculation device 60 calculates the engine speed from a signal representing the input crank angle.

  Further, the engine torque calculation device 60 is configured to calculate engine mechanical loss, pump loss, engine coolant pump, generator from engine combustion torque calculated from the amount of air flowing into the cylinder, engine speed, ignition timing, and air-fuel ratio. The engine torque is obtained by subtracting the torque for driving the compressor for the air conditioner.

  FIG. 2 is an example of an engine torque map showing the relationship among engine torque, engine speed, and throttle opening. The engine torque calculation device 60 may obtain the engine torque corresponding to the throttle opening degree input from the throttle opening degree sensor 110 and the calculated engine speed with reference to this map.

  In FIG. 1, a tire dynamic radius input device 15, a gear position detection device 16, and an engine torque calculation device 60 are electrically connected to the driving force calculation device 40, and the tire dynamic load is input from the tire dynamic radius input device 15. A signal representing the radius, a signal representing the gear ratio in the gear stage of the transmission from the gear stage detection device 16, and a signal representing the engine torque from the engine torque calculation device 60 are input. The driving force calculation device 40 calculates the vehicle driving force from these signals.

  The propulsion force calculation device 50 is electrically connected to the speed sensor 17 and the vehicle weight detection device 18, and a signal indicating the detected vehicle speed from the speed sensor 17 and the vehicle detected from the vehicle weight detection device 18. A signal indicating weight is input. The propulsive force calculating device 50 calculates the vehicle propulsive force from these signals.

  Further, the tire resistance input device 11 of the sensor unit 10, the road surface gradient detection device 20, the vehicle weight detection device 18 of the sensor unit 10, and the maximum speed calculation device 30 are electrically connected to the running resistance calculation device 70. A signal indicating a value indicating the tire type and air pressure from the tire condition input device 11, a signal indicating the detected road surface gradient from the road surface gradient detecting device 20, and a signal indicating the detected vehicle weight from the vehicle weight detecting device 18. A signal representing the calculated maximum vehicle speed is input from the maximum speed calculation device 30.

  Based on the signal input to the running resistance calculation device 70, the rolling resistance estimation device 71, the gradient resistance calculation device 72, and the air resistance estimation device 73 are respectively rolled resistance value (Rr), gradient resistance value (Re), and air resistance value. (Ra) is estimated or calculated, and the running resistance calculation device 70 calculates a running resistance value based on those estimated or calculated values.

  Rolling resistance is resistance generated by energy loss based on dynamic deformation of the tire that occurs between the road surface and the tire contact surface, and increases in proportion to the vehicle weight and rolling resistance coefficient. Can be sought.

Rolling resistance value (Rr) = Wμ (1)
Here, the unit of the rolling resistance value (Rr) is (kg), W is the vehicle weight (kg), and μ is the rolling resistance coefficient.

  The rolling resistance estimation device 71 receives signals representing the rolling resistance coefficient and the vehicle weight according to the tire type from the tire condition input device 11 and the vehicle weight detection device 18 of the sensor unit 10, respectively, and the rolling resistance is based on these signals. Estimate the value (Rr).

  The gradient resistance is a resistance generated when traveling on an inclined road surface, and is proportional to the vehicle weight and the road surface gradient, and can be obtained from the following equation.

Gradient resistance value (Re) = Wsin θ (2)
Here, the unit of the gradient resistance value (Re) is (kg), W is the vehicle weight (kg), and θ is the road surface gradient.

  The gradient resistance calculation device 72 receives signals representing the road surface gradient and the vehicle weight from the road surface gradient detection device 20 and the vehicle weight detection device 18 of the sensor unit 10, respectively, and based on these signals, calculates the gradient resistance value (Re) of the road surface. calculate.

  The air resistance is a resistance generated by the friction between the surface of the vehicle body and the air, and is proportional to the projected area of the front surface of the vehicle and the vehicle traveling speed, and can be obtained from the following equation.

Air resistance value (Ra) = λSV ² (3)
Here, the unit of the air resistance value (Ra) is (kg), λ is the air resistance coefficient (including air density) (kg · s ² / m ⁴ ), S is the projected area on the front surface of the vehicle (m ² ), and V is Vehicle traveling speed (m / s).

  The air resistance estimation device 73 receives, for example, a signal representing the air resistance coefficient and the vehicle front projection area stored in advance from the memory 180, and also receives a signal representing the maximum vehicle speed from the maximum speed calculation device 30, and receives these signals. Based on the above, the air resistance value (Ra) is calculated.

  Next, a travel resistance calculation device 70, a driving force calculation device 40, and a propulsion force calculation device 50 are electrically connected to the limit request torque calculation device 80. From these devices, the rolling resistance value, the gradient, respectively, are connected. Signals representing a running resistance value, a vehicle driving force, and a vehicle propulsive force, each consisting of a resistance value and an air resistance value, are input.

  Note that the difference between the vehicle driving force and the vehicle driving force is the running resistance value.

  Based on the input travel resistance value, vehicle driving force, and vehicle propulsion force, the limit request torque calculating device 80 balances the traveling resistance value and the vehicle driving force when traveling at a constant maximum vehicle speed, that is, An engine torque (hereinafter referred to as “restricted request torque”) required to create a state without vehicle propulsion is calculated.

  However, the state where there is no vehicle driving force is achieved when the vehicle driving force and the running resistance value completely match, but the present invention is not limited to this, and the balance between the driving force of the vehicle and the running resistance value is balanced. Even if there is a slight deviation, the required torque limit may be such that the driving force of the vehicle approximates the running resistance value as long as it is within a range or error in which the effect of preventing the occurrence of overspeed is obtained.

  For this reason, in this specification, when the expression “the vehicle driving force and the running resistance value match” is included, “matching” includes approximation.

  That is, the limit request torque can be the engine torque when the vehicle driving force and the running resistance value completely match or approximate.

  As described above, the running resistance value calculated by the running resistance calculation device 70 is changed at least according to a change in the road surface gradient. For this reason, the limit request torque calculated by the limit request torque calculation device 80 is changed based on the change in the running resistance value.

  Thus, by changing the limit request torque according to the change in the running resistance value, it is possible to prevent the convergence to the upper limit engine speed (for example, the maximum engine speed) from being deteriorated due to the change in the running state of the vehicle. Thus, it is possible to stably prevent the occurrence of over-rotation.

  The reason why it is desirable to change the limit request torque according to the change in the running resistance value is as follows. The gradient of the road surface of the vehicle changes from moment to moment. For example, when the actual engine speed converges to the upper limit engine speed and the descending gradient increases and the running resistance value decreases, vehicle propulsion is generated. It will be. For this reason, the restriction request torque at this time cannot maintain the convergence to the upper limit engine speed, and the engine speed may increase to cause overspeed.

  Therefore, for example, a change in road surface gradient is detected by the road surface gradient detection device 20 based on acceleration information acquired from the G sensor 12, road information acquired from the navigation system 13, and image information captured by an in-vehicle camera (not shown). If the limit request torque is changed so as to cancel the vehicle propulsion force in accordance with the change in the road surface gradient, the convergence of the engine speed to the upper limit engine speed can be stably maintained.

  The torque limit control device 90 is electrically connected to a limit request torque calculation device 80, an engine torque calculation device 60, and a crank angle sensor 120. A signal indicating the limit request torque from the limit request torque calculation device 80, and an engine A signal representing the calculated engine torque and a signal representing the detected crank angle are input from the torque calculation device 60 and the crank angle sensor 120.

  The torque limit control device 90 executes the torque limit control which is the engine speed determined based on the signal detected by the crank angle sensor 120 and the engine speed for determining whether to execute the torque limit control. Whether to start execution of torque limit control is determined based on the engine speed.

  The torque limit control execution engine speed is obtained based on the relationship between the time until the engine torque reaches the limit request torque and the state of increase in the engine speed. The time until the engine torque reaches the limit request torque is determined based on the difference between the current engine torque and the limit request torque, and the increase state of the engine speed is determined based on the rotational angular acceleration of the engine.

  FIG. 3 shows an example of a map used for calculating the torque limit control execution engine speed. The torque limit control execution engine speed is obtained from the correspondence between the difference between the current engine torque and the limit request torque, and the rotational angular acceleration of the engine. The map of FIG. 3 is created in advance and stored in the memory 180.

  Here, the torque limit control means that if the engine speed becomes equal to or higher than the torque limit execution engine speed, the engine torque is forcibly decreased regardless of the driver's required torque, and the engine speed is the upper limit engine speed. Control that does not exceed. Specifically, for example, the throttle opening is reduced, the intake air amount is limited by controlling the closing timing of the intake valve and the exhaust valve, the ignition timing is retarded, the fuel injection is stopped, The engine torque is forcibly reduced by, for example, restarting, and thereby the engine speed is controlled so as not to exceed the upper limit engine speed.

  In the torque limit control, the engine torque calculated by the engine torque calculation device 60 exceeds the limit request torque input from the limit request torque calculation device 80, and the actual engine speed is the torque limit control execution engine speed. It is executed when it exceeds.

  In order to achieve such torque limit control, the torque limit control device 90 calculates the limit intake air amount as the intake air amount necessary for realizing the limit request torque at the upper limit engine speed. The restriction of the intake air amount can be realized by restricting the throttle opening or by controlling the operating angle of the exhaust valve 160 or the intake valve 170.

  By controlling the operating angle of the exhaust valve 160 or the intake valve 170, for example, if the timing of opening control of the intake valve is advanced or the closing control of the exhaust valve is delayed, the intake valve and the exhaust valve are At the same time, the amount of overlap that is open increases, so that part of the exhaust gas remains in the cylinder. As a result, the amount of intake air can be limited by the residual amount.

  When executing the torque limit control, the torque limit control device 90 reads a map for calculating the torque limit procedure and the torque limit control execution engine speed from the memory 180. Next, based on the torque limiting procedure and map, a control signal is supplied to the control target of ignition coil 130, injector 140, slot valve 150, exhaust valve 160 or intake valve 170 of engine 100.

  For example, the ignition coil 130 of the engine 100 is supplied with a signal for retarding the ignition timing, and the injector 140 is supplied with a signal for stopping and restarting or reducing the fuel injection amount. Is supplied with a signal for limiting the amount of intake air by restricting the throttle opening, and the exhaust valve 160 or the intake valve 170 is supplied with a signal for controlling the operating angle of those valves. These controls can be performed by changing each control object to a command value.

  On the other hand, for example, if it is attempted to realize from the start of the torque limit control to the convergence of the engine speed only by the throttle valve opening control, a time delay occurs until the required limit torque is reached. The torque controllability from the start of the limit until the required limit torque is reached deteriorates. Therefore, it is necessary to advance the timing for starting the torque limit control.

  For this reason, as described above, the timing of starting the torque limit control is excessively performed by performing the torque control using the retard of the ignition timing, the operating angle control of the exhaust valve and the intake valve, and the stop of the fuel injection as described above. It is possible to avoid speeding up, and it is possible to prevent overspeed by improving the convergence of the engine speed.

  In addition, the retard of the ignition timing increases the temperature of the exhaust gas purification catalyst. And the exhaust gas purification catalyst which became excessively high temperature falls in the performance which purifies exhaust gas. For this reason, as soon as the time delay to reach the required limit torque due to the restriction of the intake air amount is resolved, the temperature of the exhaust gas purification catalyst is suppressed from rising immediately by returning to the ignition timing before restricting the intake air amount. Is possible.

  In addition, repeated stop and restart of fuel injection also cause a rise in the temperature of the exhaust gas purification catalyst. For this reason, if the restriction of the intake air amount is promptly performed when the engine torque is reduced due to the stop of the fuel injection, the target torque can be converged without repeatedly stopping and restarting the fuel injection.

  In order to maintain the upper limit engine speed, as described above, the engine torque corresponding to the road surface gradient may be calculated while monitoring the change in the road surface gradient, and control may be performed based on the calculated engine torque.

  FIG. 4A to FIG. 4F illustrate the behavior of each controlled object when the torque limit control is started by the engine overspeed prevention control device according to the embodiment of the present invention. The time chart for showing is shown. In each figure, the horizontal axis represents time, and the vertical axis is assumed to increase or advance as it goes upward.

  FIG. 4B shows the behavior of the engine speed. When the current engine speed exceeds the torque limit control execution engine speed indicated by the broken line at t1, the torque limit control device 90 starts executing the torque limit control. When execution of the torque limit control is started, the rate of increase of the engine speed is then reduced, and the engine speed completely matches the upper limit engine speed (for example, the maximum engine speed) or the upper limit engine speed. The rotation speed is close to the rotation speed (or the maximum engine rotation speed).

  Therefore, in the present specification, when it is expressed that the engine speed matches the upper limit engine speed, the engine speed completely matches the upper limit engine speed or approximates the upper limit engine speed. It means to become.

  If the actual engine speed matches the maximum engine speed, deceleration caused by torque limitation can be prevented, so that the driver feels uncomfortable. Further, if the actual engine speed matches the upper limit engine speed smaller than the maximum engine speed, it is possible to prevent overspeed even if the engine speed slightly increases during torque limitation.

  FIG. 4A shows the behavior of the vehicle speed. As shown in this figure, the vehicle speed increases linearly until t1, but when the torque limit control is started at t1, the linear increase rate of the vehicle speed decreases and then remains constant. Converge to speed.

  FIG. 4C shows the behavior of the ignition timing. As shown in this figure, the ignition timing is the same until t1, but when the execution of the torque limit control is started at t1, the ignition timing is retarded at once, and then is linearly advanced to t2. The original ignition timing is reached at t2.

  FIG. 4D shows the behavior of the throttle opening and the intake air amount. As shown in this figure, the throttle opening is the same up to t1, but when execution of torque limit control is started at t1, the throttle opening is limited to a predetermined opening, and then the throttle The opening degree is maintained. However, even if the throttle opening is limited to a predetermined opening at t1, the intake air amount is limited with a time delay, and at t2, the intake air amount is limited.

  FIG. 4 (e) shows the behavior of the engine torque. Corresponding to the delay in restricting the intake air amount as shown in FIG. 4D, when the torque limit control is started at t1 in FIG. 4E, the engine torque is Although it tries to maintain at the driver request torque, it decreases with a delay in time, and reaches a constant value at the limit request torque at about t2.

  FIG. 4F shows the behavior of the vehicle driving force and the running resistance value. The difference between the vehicle driving force and the running resistance value is a vehicle driving force (in other words, an acceleration force). In this figure, when the torque limit control is executed at t1, the vehicle driving force decreases with a slight delay corresponding to the behavior of the engine torque shown in FIG. 4 (e), and then coincides with the running resistance value. . The state where the vehicle driving force matches the running resistance value indicates a state where the vehicle is neither accelerated nor decelerated. On the other hand, the running resistance value and the vehicle driving force do not coincide with each other, and a deviation occurs between them. When the vehicle driving force is larger than the running resistance value, acceleration corresponding to the deviation occurs. Is shown.

  FIG. 5 shows an example of a flowchart of success / failure determination of the torque limit control execution condition in the engine overspeed prevention control device according to the embodiment of the present invention.

  First, the driving force calculating device 40, the propulsive force calculating device 50, and the gradient resistance calculating device 72 of the control unit 1 calculate a vehicle driving force, a vehicle propulsive force, and a road surface gradient resistance value, respectively (step S51).

  Next, the rolling resistance estimation device 71 and the air resistance estimation device 73 estimate a rolling resistance value and an air resistance value, respectively (step S52).

  Next, the maximum speed calculation device 30 calculates a set upper limit speed. In this embodiment, the maximum speed calculation device 30 calculates the vehicle maximum speed as an example (step S53).

  Next, the running resistance calculation device 70 calculates the running resistance value at the vehicle maximum speed calculated in step S53 (step S54).

  Next, the limit request torque calculation device 80 calculates the limit request torque based on the vehicle driving force and vehicle propulsion force obtained in step S51 and the running resistance value obtained in step S54 (step S55).

  Next, the torque limit control device 90 calculates the engine rotation angular acceleration based on the signal from the crank angle sensor 120 (step S56).

  Subsequently, the torque limit control device 90 determines whether or not the driver request torque supplied from the engine torque calculation device 60 is larger than the limit request torque obtained in step S55 (step S57).

  When it is determined in step S57 that the driver request torque is greater than the limit request torque (YES), the torque limit control device 90 determines that the engine rotation angular acceleration calculated in step S56 is a predetermined value selected from arbitrary values. It is determined whether or not it is large (step S58).

  When the torque limit control device 90 determines in step S58 that the engine rotational angular acceleration is greater than a predetermined value (YES), the engine state is in a rotationally increased state. A limit control execution engine speed corresponding to the difference between the current engine torque and the limit request torque is calculated (step S59).

  Note that the engine speed can be calculated in advance according to the engine rotation angular acceleration and the difference between the engine torque and the limit request torque, and can be created as a map. The limit control execution engine speed may be selected from the map without calculating the engine speed.

  Subsequent to step S59, the torque limit control device 90 determines whether or not the engine speed is larger than the torque limit control execution engine speed (step S60). Here, when the torque limit control device 90 determines that the engine speed is larger than the torque limit control execution engine speed (YES), the torque limit control device 90 starts executing the torque limit control (step S61). The process for determining whether or not the control execution condition is successful is terminated.

  On the other hand, when the torque limit control device 90 determines in step S60 that the engine speed is equal to or lower than the torque limit control execution engine speed (NO), then the engine speed is calculated from the limit control execution engine speed. It is determined whether or not the rotation speed is greater than the predetermined rotation speed (step S62).

  When the torque limit control device 90 determines in step S62 that the engine speed is greater than the speed obtained by subtracting the predetermined speed from the limit control execution engine speed (YES), the torque limit control execution is not required. Therefore, the process of determining whether the torque limit control execution condition is successful is terminated.

  Further, when it is determined in step S57 that the driver request torque is equal to or less than the limit request torque (NO), the torque limit control device 90 determines in step S58 that the engine rotation angular acceleration is equal to or less than a predetermined value. (NO) or when it is determined in step S62 that the engine speed is equal to or lower than the engine speed obtained by subtracting the predetermined engine speed from the engine speed limit for executing the torque limit control (NO), the torque limit control execution condition is not satisfied. If it is determined that there is any (step S63), the process for determining whether or not the torque limit control execution condition is satisfied is terminated.

  FIG. 6 shows an example of a flowchart of torque limit control execution control after determination of success or failure of the torque limit control execution condition in the engine overspeed prevention control device according to the embodiment of the present invention.

  The torque limit control device 90 of the control unit 1 determines whether or not the torque limit control execution condition is satisfied based on whether or not the torque limit control execution condition is satisfied (step S71). Here, when it is determined that the torque limit control execution condition is not satisfied (NO), the torque limit control device 90 ends the torque limit control execution control process.

  When it is determined in step S71 that the torque limit control execution condition is satisfied (YES), the torque limit control device 90 calculates the throttle valve opening corresponding to the limit request torque and controls the slot valve 150. The command value is changed (step S72).

  Next, the torque limit control device 90 selects one or a plurality of torque limit methods from the first to the fourth according to the engine rotation angular acceleration and the difference between the current engine torque and the limit request torque. Then, a command value for controlling each device to be controlled is calculated (step S73).

  Subsequently, the torque limit control device 90 executes the torque limit method in order to select and execute one or a plurality of torque limit methods from the first to the fourth (step S74), and torque limit control execution control. Terminate the process.

  FIG. 7 shows an example of a flowchart for the torque limiting method execution process in the torque limit control execution control process of FIG.

  First, the torque limit control device 90 determines whether or not to select the torque limit method (first) (step S81), and when selected (YES), controls the ignition timing of the ignition coil 130. The value is changed to a command value (step S82).

  Whether or not the torque limit control device 90 selects the torque limit method (second) after executing step S82 or when the torque limit method (first) is not selected in step S81 (NO). (YES), the value for controlling the operating angle of the variable intake valve 170 is changed to a command value (step S84).

  The torque limiting control device 90 selects whether or not to select the torque limiting method (third) after executing step S84 or when the torque limiting method (second) is not selected in step S83 (NO). (Step S85), when selecting (YES), the value for controlling the operating angle of the variable exhaust valve 160 is changed to a command value (step S86).

  Whether or not torque limiting control device 90 selects torque limiting method (fourth) after executing step S86 or when torque limiting method (third) is not selected in step S85 (NO). (YES), a fuel injection stop signal is sent to the injector 140 (step S88).

  The torque limit control device 90 ends the torque limit method execution process after executing Step S88 or when the torque limit method (fourth) is not selected in Step S87 (NO).

  According to the above embodiment of the present invention, the following effects can be obtained.

  (1) Engine damage can be avoided to prevent over-rotation.

  (2) Torque limitation is not performed only by control that greatly reduces the torque as in fuel cut control, but torque limit control that uses intake air amount control, ignition timing control, and fuel cut control is performed. Reduces the shock caused by restrictions.

  (3) Since it converges to the upper limit engine speed (for example, the maximum engine speed), rapid deceleration due to a decrease in the engine speed can be avoided.

  (4) The basic control is to reduce the torque by reducing the intake air amount by restricting the throttle valve opening. If the throttle control is poor only by restricting the throttle valve opening, the fuel cut control or Since the ignition timing is retarded, thermal damage to the exhaust gas purification catalyst can be avoided.

  As described above, the embodiments of the present invention have been described, but it is obvious that those skilled in the art can make changes, modifications, and alterations without departing from the scope of the present invention. Such alterations, modifications, and variations and equivalents are intended to be included within the scope of the claims.

DESCRIPTION OF SYMBOLS 1 Control part 10 Sensor part 11 Tire condition input device 12 G sensor 13 Navigation system 14 Upper limit engine speed setting device 15 Tire moving radius input device 16 Gear stage detection device 17 Speed sensor 18 Vehicle weight detection device 20 Road surface gradient detection device 30 The highest Speed calculation device 40 Driving force calculation device 50 Propulsion force calculation device 60 Engine torque calculation device 70 Travel resistance calculation device 80 Limit request torque calculation device 90 Torque limit control device 100 Engine 110 Throttle opening sensor 120 Crank angle sensor 130 Ignition coil 140 Injector 150 Throttle valve 160 Exhaust valve 170 Intake valve 180 Memory

Claims (5)

In an overspeed prevention control device that prevents overspeed of the engine by limiting torque to the engine mounted on the vehicle
A limit request torque for matching the engine speed to the upper limit engine speed is obtained, and when the engine speed becomes equal to or higher than the limit speed for executing the torque limit, based on the limit request torque A control unit for controlling the engine torque;
The over-rotation prevention control device, wherein the control unit obtains the limit request torque based on a running resistance value of the vehicle.   2. The control unit according to claim 1, further comprising: approximating the upper limit engine speed to make the engine speed at the time of obtaining the limit required torque coincide with the upper limit engine speed. The over-rotation prevention control device described in 1.   The overspeed prevention control device according to claim 1, wherein the control unit obtains an engine torque when the driving force of the vehicle coincides with the travel resistance value as the limit request torque. The running resistance value is changed according to at least a change in road gradient,
The overspeed prevention control device according to any one of claims 1 to 3, wherein the control unit changes the limit request torque based on the change in the running resistance value.   The said control part calculates | requires the said limitation rotational speed based on the relationship between the time until engine torque reaches the said limitation request torque, and the raise state of the said engine rotation speed. The over-rotation prevention control device according to any one of the above.

Images