JP2015135168A - Shift control device for vehicle with auxiliary brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To give no sense of incongruity to a driver by producing the braking effect of an auxiliary brake with the switching operation of the driver even when the revolving speed of an engine belongs to an inoperative low-revolving-speed region.SOLUTION: A shift control device for a vehicle with auxiliary brake includes a transmission 15, shift control means 18 for performing shift control of the transmission 15, and an auxiliary brake 13 operative when the pressing amount of an accelerator pedal 11 is zero in the state that an operation switch 26 is on. Herein, revolving speed detecting means 21 is provided for detecting the revolving speed of an engine 12, and an inoperative low-revolving-speed region is set where the auxiliary brake 13 is inoperative. In the case that the operation switch 26 is on and the pressing amount of the accelerator pedal 11 is zero, when the revolving speed detecting means 21 detects the revolving speed which belongs to the inoperative low-revolving-speed region, the shift control means 18 allows the downshift of the transmission so that the revolving speed of the engine 12 exceeds the inoperative low-revolving-speed region.

Description

  The present invention relates to a shift control device for a vehicle with an auxiliary brake including an auxiliary brake having an inactive low rotational speed range.

  Conventionally, many commercial vehicles such as trucks are equipped with an automatic transmission. As such an automatic transmission device, there is known an automatic transmission device using a mechanical clutch and a gear-type transmission, and provided with various sensors for detecting these operating states and an actuator for driving them. In such a vehicle shift control device, instead of manually shifting with the driver's operating force, the control unit controls the actuator based on detection signals from various sensors, and the transmission is shifted up or down according to a predetermined shift map. The transmission is controlled to be shifted to the target shift speed determined from the driver request torque.

  In addition, such a relatively large vehicle includes a compression release brake, an exhaust brake, and the like that operate when the accelerator is off or when the main brake is on as an auxiliary to the main brake device (see, for example, Patent Document 1). Auxiliary brakes such as compression release brakes and exhaust brakes are activated when the driver releases the accelerator pedal and sets the amount of depression to zero when the auxiliary brakes are enabled by the driver's switch operation. On the other hand, when the driver depresses the accelerator pedal, the auxiliary brake state is released and the vehicle can be accelerated.

  On the other hand, if an auxiliary brake such as a compression release brake or an exhaust brake is operated when the rotational speed of the engine is low, the engine may be stopped. In order to avoid stopping the engine at this low rotational speed, such an auxiliary brake is provided with an inactive low rotational speed region so that the rotational speed of the engine belongs to the inactive low rotational speed region. In the case of a low rotation speed, the auxiliary brake is set to a valid state by the switch operation, and even if the driver releases the accelerator pedal and sets the depression amount to zero, the auxiliary brake is not operated. I am doing so.

JP-A-9-2105

  However, since the operation of the auxiliary brake is determined by whether or not the driver operates the switch, the auxiliary brake is activated when the engine rotation speed is in the inactive low rotation speed range. If this is not done, the driver's sensibility is not preferable because it gives the driver that the auxiliary brake does not operate despite the switch operation.

  In order to eliminate this point, it is conceivable that the auxiliary brake is operated even when the rotational speed of the engine belongs to the inoperative low rotational speed range. However, in that case, it is necessary to avoid that the engine stops.

  It is an object of the present invention to obtain a braking action by an auxiliary brake by a driver's switch operation without stopping the engine even when the engine rotation speed belongs to the inactive low rotation speed range, and the driver feels uncomfortable. It is an object of the present invention to provide a shift control device for a vehicle with an auxiliary brake that does not give a torque.

  The present invention relates to a transmission, a shift control means for shifting the transmission to a target shift stage obtained from a driver request torque by shifting up or down, and an accelerator pedal in a state where an operation switch is turned on. This is an improvement of a shift control device for a vehicle with an auxiliary brake, which is equipped with an auxiliary brake that can be operated when the amount of stepping on becomes zero.

  The characteristic structure is provided with a rotation speed detection means for detecting the rotation speed of the engine, has an inoperative low rotation speed range where the auxiliary brake cannot be operated, and the shift control means has an operation switch and When the accelerator pedal depression amount is zero and the rotational speed detection means detects a rotational speed that belongs to the inactive low rotational speed range, the transmission is set so that the rotational speed of the engine exceeds the inactive low rotational speed range. There is a place to shift down.

  In the shift control device for a vehicle with an auxiliary brake according to the present invention, when the rotational speed detecting means detects the rotational speed of the engine belonging to the inactive low rotational speed range, the rotational speed detecting means causes the rotational speed of the engine to be in the inactive low rotational speed range. Therefore, the auxiliary brake can be operated with the engine speed increased. As described above, even when the engine rotational speed belongs to the inactive low rotational speed region, the auxiliary brake can be operated with the engine rotational speed being increased when the accelerator pedal depression amount becomes zero. Therefore, it is possible to sufficiently obtain the deceleration action of the auxiliary brake while avoiding that the engine stops. As a result, the driver who operates the switch for operating the auxiliary brake does not feel uncomfortable.

It is a flowchart which shows operation | movement until the auxiliary | assistant brake of the transmission control apparatus of this invention is actuated. It is a block diagram of a vehicle including the shift control device.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 2 shows a main configuration of a vehicle 10 to which the transmission of the present invention is applied. The vehicle 10 is a large vehicle such as a truck. The vehicle 10 includes a main brake device (not shown) capable of directly braking the rotation of the front wheels 17a and the rear wheels 17b, and a driver stepping on the main brake device. A brake pedal is provided that is actuated by. The vehicle 10 is provided with a compression release brake 13 as an auxiliary brake that is activated when the accelerator pedal 11 is not depressed or when the main brake device is activated, as an auxiliary to the main brake device. It is done. The compression release brake 13 as the auxiliary brake is disposed in the exhaust passage of the engine 12 and includes an auxiliary brake ECU (electronic control unit) 14 that is a control device for the compression release brake 13.

  A transmission 15 is connected to the engine 12, and a rear wheel 17 b is further connected via a drive shaft 16. The transmission 15 that transmits the output of the engine 12 to the rear wheel 17b is a mechanical automatic transmission 15 that is controlled by an automatic transmission ECU 18 that constitutes a transmission control means, and the automatic transmission ECU 18 shifts the transmission 15. It is configured to be up or down. The automatic transmission ECU 18 is provided with a memory 18a, and a memory 18a stores a shift map in which a target shift stage according to conditions such as driver required torque is described. Here, the driver request torque is obtained from the opening degree of the throttle that opens and closes when the accelerator pedal 11 is depressed and the vehicle speed.

  The vehicle 10 is provided with an engine ECU 19 that is a control device for the engine 12. The engine ECU 19 connects its control output to the fuel injection device 12 a in the engine 12.

  Further, the vehicle 10 is provided with an accelerator sensor 24 that detects the amount of depression of the accelerator pedal 11, a vehicle speed sensor 22 that detects the traveling speed of the vehicle, and a rotational speed sensor 21 that detects the rotational speed of the cran shaft of the engine 12. It is done. Further, the vehicle 10 is provided with an operation switch 26 that enables the compression release brake 13 that is an auxiliary brake to be operated when the depression amount of the accelerator pedal 11 is zero.

  The auxiliary brake ECU 14, automatic transmission ECU 18, engine ECU 19, rotational speed sensor 21, vehicle speed sensor 22, accelerator sensor 24, operation switch 26 and the like described above are connected to other devices (not shown) via a CAN (Controller Area Network) 23. Connected and configured to communicate with each other.

  When the driver depresses the accelerator pedal 11 to drive the vehicle 10, the engine ECU 19 increases or decreases the flow rate of fuel supplied to the engine 12 according to the amount of depression of the accelerator pedal 11, and rotates the engine 12 to the desired rotation. Configured to be maintained. When the amount of depression of the accelerator pedal 11, the rotational speed of the engine 12 detected by the rotational speed sensor 21, or the traveling speed of the vehicle 10 detected by the vehicle speed sensor 22 changes, the automatic transmission ECU 18 serving as a shift control means The transmission 15 is configured to shift-control to a target shift speed determined from the driver request torque. That is, the automatic transmission ECU 18 is configured to shift-control the transmission 15 to a target shift stage determined from the driver-requested torque according to a shift map stored in the memory 18a by shifting the transmission 15 up or down. Is done.

  On the other hand, when the driver releases the depression of the accelerator pedal 11 and the accelerator sensor 24 detects and outputs the fact that the accelerator pedal 11 is released, the engine ECU 19 determines the fuel flow rate supplied to the engine 12 as the engine flow rate. Twelve rotations are configured to be the minimum amount necessary to maintain at idling speed. For this reason, when the traveling gear is selected in the transmission 15 and the accelerator sensor 24 detects and outputs the fact that the accelerator pedal 11 is released while the vehicle 10 is traveling at a corresponding speed, the traveling speed is maintained at the idling speed. The engine 12 to be braked is in a so-called engine brake state in which the rotation of the rear wheel 17b is braked.

  The compression release brake 13 in this embodiment operates in such an engine brake state, and injects fuel when the piston reaches near the top dead center in the compression stroke of the diesel engine 12. Without opening the exhaust valve, the compression of the air in the cylinder is released. Then, by closing the exhaust valve after the piston has passed through the top dead center, the pressure in the cylinder is lowered as the piston is lowered, thereby providing resistance to crankshaft rotation. Then, the rotational speed of the engine 12 that is rotationally driven by the rear wheel 17b in the engine brake state is further decelerated, whereby the compression release brake 13 substantially acts as a brake for the vehicle 10.

  In this embodiment, the operation switch 26 for operating the compression release brake 13 is configured such that the driver tilts the operation lever 26a. That is, the basic state indicated by the broken line in FIG. 2 indicates the off state. In this off state, even if the engine is in the brake state, the auxiliary brake ECU 14 opens the exhaust valve when the piston reaches near the top dead center. It is configured not to do anything. When the operation lever 26a is tilted from the OFF state to the tilted state indicated by the solid line, the operation switch 26 is turned on. When the operation switch 26 is thus turned on, in the engine brake state, the auxiliary brake ECU 14 operates the compression release brake 13 and opens the exhaust valve when the piston reaches near the top dead center. After passing through the top dead center, the exhaust valve is closed to lower the pressure in the cylinder, thereby further reducing the rotational speed of the engine 12.

  On the other hand, the compression release brake 13 which is this auxiliary brake is provided with an inoperable inactive low rotational speed region in which the rotational speed of the engine 12 cannot be reduced. This inactive low rotational speed region is provided to prevent the engine 12 from stopping, and is set in the vicinity of a so-called idle rotational speed.

  When the operation lever 26a of the operation switch 26 is tilted as shown by a solid line, the rotation speed sensor 21 serving as the rotation speed detection means is inactivated at a low rotation speed in the engine brake state where the depression amount of the accelerator pedal 11 is zero. When the rotational speed belonging to the range is detected, the automatic transmission ECU 18 shifts down the transmission 15 and the rotational speed of the engine 12 detected by the rotational speed sensor 21 serving as the rotational speed detection means exceeds the inoperative low rotational speed range. Configured as follows.

  Next, the operation of the shift control device for a vehicle with an auxiliary brake configured as described above will be described.

  First, FIG. 1 shows the control in the automatic transmission ECU 18 which is a transmission control means. As shown in FIG. 1, when a traveling gear is selected in the transmission 15 and the vehicle 10 is traveling at a corresponding speed, when the driver releases the depression of the accelerator pedal 11 to enter the engine brake state, the accelerator pedal is released. The fact that 11 is released is detected and output by the accelerator sensor 24. The automatic transmission ECU 18 that has detected that the engine is in the brake state (S21) based on this detection output is then operated by the operation switch 26 in the driver's seat and the operation lever 26a is in the off state indicated by the broken line in FIG. It is confirmed whether there is a tilted state indicated by a solid line (S22). That is, the driver can select whether or not to use the compression release brake 13 as an auxiliary brake. As a result, when the operation lever 26a of the operation switch 26 is in the off state indicated by the broken line in FIG. 2, if the auxiliary brake is already operating, the auxiliary brake is released (S23) and the process returns. .

  On the other hand, when the operation lever 26a of the operation switch 26 is in the tilted state shown by the solid line in FIG. 2, the intention to use the compression release brake 13 is expressed by the driver in the engine brake state. Next, the automatic transmission ECU 18 inputs the rotational speed of the engine 12 from the rotational speed sensor 21 (S24). Then, it is determined whether or not the rotational speed belongs to the inoperative low rotational speed region of the compression release brake 13 (S25).

  As a result, if the rotational speed detected by the rotational speed sensor 21 does not belong to the inoperative low rotational speed region of the compression release brake 13 and exceeds the inoperative low rotational speed region, the auxiliary brake is not shifted down. A command is issued to the ECU 14, the compression release brake 13 as an auxiliary brake is operated based on the operation position of the operation lever 26a (S26), and the process returns. That is, the operating speed of the operating lever 26a of the operating switch 26 shown in the solid line in FIG. 2 is in the engine braking state, and the rotational speed sensor 21 serving as the rotational speed detecting means exceeds the inoperative low rotational speed range. Is detected, the auxiliary brake ECU 14 operates the compression release brake 13. Therefore, when the driver does not like the operation of the compression release brake 13 in the engine brake state, the operation release 26 is operated by turning the operation lever 26a of the operation switch 26 in the off state indicated by the broken line in FIG. You can choose not to.

  On the contrary, when the operation switch 26 is turned on and the depression amount of the accelerator pedal 11 is zero, the rotational speed sensor 21 serving as the rotational speed detection means detects a rotational speed belonging to the inoperative low rotational speed range. (S25) The automatic transmission ECU 18, which is a shift control means, shifts down the transmission 15 (S27). In the downshift (S27) of the transmission 15, the automatic transmission ECU 18 serving as a shift control means detects that the rotational speed sensor 21 serving as the rotational speed detecting means detects a rotational speed that exceeds the inoperative low rotational speed range. The number of stages is calculated and the number of stages is shifted down.

  The rotational speed of the engine 12 increases due to the downshift, and after the rotational speed of the engine 12 exceeds the inoperative low rotational speed range due to the downshift, the auxiliary brake ECU 14 activates the compression release brake 13 as an auxiliary brake. Operate (S26) and return. As a result, the braking action by the auxiliary brake 13 can be obtained without stopping the engine 12, and the driver who tries to obtain the braking action by the auxiliary brake 13 by the switch operation does not give a sense of incongruity.

  In the above-described embodiment, the case where the auxiliary brake is the compression release brake 13 has been described. However, the auxiliary brake is not limited to the compression release brake 13 as long as it has an inoperative low rotation speed range. For example, the auxiliary brake may be a retarder or an exhaust brake.

  Although not shown, the retarder is an electric braking device used for a large vehicle or the like. In a widely known form, a generator is connected to a propeller shaft for driving an axle and rotates, and a resistor is connected to the electrical output of the generator. When the retarder is operated to the braking state by operating the switch provided in the driver's seat, the output current of this generator flows to the resistor, the mechanical load on the propeller shaft increases, the vehicle enters the braking state, and the main brake device is It can help.

  The exhaust brake has a structure in which an open / close valve is provided in the exhaust passage of the engine 12. Specifically, the auxiliary brake ECU 14 is configured to close the on-off valve provided in the exhaust passage of the engine 12 when the driver operates the operation switch 26 in the engine brake state. When the on-off valve is closed, the exhaust pressure in the engine 12 increases and the rotational speed is reduced, so that the exhaust brake acts substantially as a brake on the vehicle 10.

  Further, in the above-described embodiment, the automatic transmission ECU 18 calculates the number of downshifts in which the rotational speed detecting means detects a rotational speed exceeding the inoperative low rotational speed range, and the downshift of the obtained number of stages is performed. Explained when to do. However, if the rotational speed detection means detects a rotational speed that belongs to the inoperative low rotational speed range, the downshift is performed until the rotational speed sensor 21 that is the rotational speed detecting means detects a rotational speed that exceeds the inoperative low rotational speed range. You may make it carry out one step.

10 Vehicle 11 Accelerator pedal 12 Engine 13 Compression release brake (auxiliary brake)
15 Automatic transmission 18 Automatic transmission ECU (transmission control means)
21 Rotational speed sensor (rotational speed detection means)
26 Operation switch

Claims (1)

A transmission (15), a shift control means (18) for shifting the transmission (15) to a target shift stage determined from a driver request torque by shifting up or down the transmission (15), and an operation In a vehicle shift control device including an auxiliary brake (13) operable when the depression amount of the accelerator pedal (11) becomes zero with the switch (26) being turned on,
Rotational speed detection means (21) for detecting the rotational speed of the engine (12) is provided,
The auxiliary brake (13) has a non-operating low rotation speed range where it cannot operate,
When the operation switch (26) is turned on and the amount of depression of the accelerator pedal (11) is zero, the speed change control means (18) is such that the rotational speed detection means (21) is not activated. With an auxiliary brake, when detecting a rotational speed belonging to a low rotational speed range, the transmission (15) is shifted down so that the rotational speed of the engine (12) exceeds the inoperative low rotational speed range A transmission control device for a vehicle.

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