JP3722945B2 - Engine output torque limiter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine output torque limiting device.
[0002]
[Prior art]
In order to respond to the speeding up of vehicles accompanying the development of expressways, the output of engines is also increasing in commercial vehicles such as trucks, but on the other hand, reduction of operating expenses by improving fuel efficiency is also required. Therefore, it is conceivable to cut the engine torque in order to effectively improve the fuel consumption. As a conventional example relating to torque cutting, a technique for cutting excessive torque has been proposed in Japanese Patent Application Laid-Open No. 6-272584 for the purpose of preventing gear breakage of the transmission. In this disclosed technology, in an engine with a supercharger, by adjusting a supercharging pressure (boost pressure) that leads to a boost compensator for a specific gear stage (shift stage) to a predetermined pressure within a boost compensator operating region, The increase correction is limited.
[0003]
[Problems to be solved by the invention]
However, since a uniform torque cut is always performed at a specific gear stage, depending on the road conditions such as uphill and the load capacity, the torque cut may cause a lack of driving force, which may impair the driving operability of the vehicle. there were.
[0004]
The present invention has been made paying attention to such problems, and it is intended to improve fuel efficiency while ensuring driving operability of the vehicle by controlling the torque cut of the engine in accordance with the load of the vehicle. To do.
[0005]
[Means for Solving the Problems]
In the first aspect of the invention, when a condition in which the transmission is in a specific gear stage, the torque cut permission flag is “1”, the accelerator opening is a predetermined value or more and the vehicle acceleration is a predetermined value or more is satisfied, Means for performing torque cut control using a torque curve that cuts a part of the torque curve for engine control, the transmission is in a specific gear stage, the torque cut permission flag is “1”, and the accelerator opening is stepped on more than a predetermined value and When a condition where the vehicle running acceleration exceeds a predetermined value is broken, torque cut control is canceled and engine control using a normal torque curve is performed, and a torque cut permission flag is set to “0”, and a vehicle shift operation is performed. Or at least one of the following: Means to "1" permission flag, a provided.
[0006]
According to a second aspect, in the first aspect, means for selecting on / off of torque cut control based on an artificial operation is provided.
[0007]
According to a third aspect, in the first aspect, means for operating an alarm in the cab at least at the start of torque cut control is provided .
[0008]
According to a fourth aspect, in the first aspect, means for displaying on the cab that torque cut control is being performed is provided.
[0012]
【The invention's effect】
In the first to fourth aspects of the invention, torque cut control is performed when the load on the vehicle is small and the driving force has a margin, and part of the fuel supply amount is saved. When the load on the vehicle increases due to the load amount of the vehicle or the road conditions, normal engine control is performed, so that driving force is ensured. That is, the fuel efficiency can be improved without impairing the driving operability of the vehicle .
[0013]
The torque cut permission flag is set to “0” when shifting to normal engine control, and “1” is set if at least one of the vehicle speed change operation or the engine speed is not less than a predetermined value is established. Therefore, the restart of torque cut control is limited until at least one of these is established. Therefore, it can be avoided that the engine repeats control between torque cut operation and normal operation due to a temporary change in road conditions such as the degree of climbing, and the driving force is insufficient when necessary. .
[0014]
The vehicle load can be accurately determined from the accelerator opening and the vehicle running acceleration. When the travel acceleration of the vehicle is smaller than the predetermined value despite the depression state where the accelerator opening is greater than or equal to the predetermined value, it is determined that the load on the vehicle is large, and the accelerator opening is larger than the predetermined value. When the traveling acceleration is as large as a predetermined value or more, it is determined that the load on the vehicle is small .
[0015]
Further, by controlling the torque cut by tangling a specific gear to the vehicle load, it is possible to accurately determine whether or not there is a margin in the driving force .
[0016]
In the second invention, the driver can select on / off of the torque cut control. When the torque cut control is turned off, the engine torque cut is not automatically performed during that period even if the road condition of the loaded vehicle changes. That is, only when the torque cut control is turned on, the torque cut operation is automatically controlled according to the load amount of the vehicle, the road condition, and the like.
[0017]
In the third aspect of the invention, the torque cut operation of the engine is automatically controlled, but an alarm device in the cab is activated at the start. As a result, the driver is alerted, and there is no need to be confused by unexpected torque reduction.
[0018]
In the fourth invention, it is possible to easily identify whether the torque cut operation is being performed or the normal operation is being performed .
[0019]
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1, 1 is a diesel engine, 2 is a clutch, 3 is a transmission, and the output shaft of the transmission 3 is connected to a rear axle via a propeller shaft (not shown). The engine fuel injection pump is provided with a governor device 1A for adjusting fuel injection charges, the clutch 2 is provided with a clutch booster 2A for performing intermittent operation, and the transmission 3 is provided with a gear shift unit 3A for driving the gear shift mechanism. Reference numeral 27 denotes a supply / discharge valve of the clutch booster 2A.
[0020]
As detection means necessary for vehicle shift control, an engine rotation sensor 29 that detects the engine speed, an accelerator opening sensor 28 that detects the amount of depression of the accelerator pedal 7 (accelerator opening), and the stroke position of the clutch 2 are detected. A clutch stroke sensor 22 to detect, a gear position sensor (incorporated in the gear shift unit 3A) to detect the shift position of the transmission 3, a vehicle speed sensor 21 to detect the rotational speed of its output shaft, and a freewheel on the main shaft And a gear rotation sensor 23 for detecting the rotation speed of the main gear.
[0021]
In order to switch between manual control and automatic control of the clutch 2, clutch switches 24 and 25 for detecting an initial position and an operating position of the clutch pedal are provided. A shift lever unit 4 is provided in the driver's cab as a shift operation means of the transmission 2 and outputs a shift position instruction signal for the shift lever 4A. The operator's cab is provided with a monitor 13 having a transmission shift position display lamp and the like, and a brake pedal switch 26 for detecting depression of a brake pedal (not shown). Is added. An alarm buzzer 13A that operates before and after the torque cut operation is disposed in the cab.
[0022]
The engine control unit 11 and the transmission control unit 12 control the speed change operation of the vehicle and the torque cut of the engine based on these output signals, and the control units 11 and 12 are connected by serial communication (LAN). When a shift request based on the lever operation of the shift lever unit 4 or a shift request based on the running state of the vehicle (vehicle speed and accelerator opening) is generated, a series of shift operations are performed to shift the gear to the required position. Control. That is, after the clutch 2 is disengaged, the gear is removed when the transmission 3 is not neutral. When the main gear rotation speed enters the synchronization region while controlling the engine rotation speed as necessary, the transmission 3 is geared.
[0023]
FIG. 2 shows a block configuration relating to engine torque cut control. In the transmission control unit 11, the vehicle acceleration is calculated by the calculation means 11 A based on the detection signal of the vehicle speed sensor 21. It is determined from the detection signal of the accelerator opening sensor 28 that the load on the vehicle is small when the vehicle acceleration is equal to or greater than a predetermined value in a high load state where the pedal depression amount is equal to or greater than the predetermined value. Basically, the torque cut may be performed based on the determination that the load on the vehicle is small. In this example, however, the transmission 3 is based on a detection signal from the gear position sensor 30 so that the transmission 3 has a specific gear (for example, , The highest speed stage) is determined, and when the vehicle load is small for a specific gear stage, it is determined that the driving force has a margin. A permission for torque cut is given by determining that the driving force has a margin. The transmission control unit 11 has a function of activating an alarm buzzer 13A in the cab at the start and release of the torque cut operation and lighting the torque cut display lamp 13B of the monitor 13 during the torque cut operation.
[0024]
The engine control unit 12 is provided with memories 12B and 12C for storing a normal engine torque curve TH and a torque cut engine torque curve TL as shown in FIG. When permission for torque cut is received from the transmission control unit 11, the engine control means 12 </ b> A that controls the governor device 1 </ b> A of the fuel injection pump responds to the detection signal of the engine rotation sensor 29 based on the detection signal of the accelerator opening sensor 28. The torque cut operation according to the engine torque curve TL is controlled. When the permission condition described above is broken, the torque cut permission disappears. At that time, the torque cut control is canceled and the normal engine control according to the engine torque curve TH is restored.
[0025]
In order to avoid repeated control between engine torque cut control and normal control due to temporary changes in road conditions such as the degree of climbing, and the lack of necessary driving force, the transmission control unit 11 is Once the torque cut control is canceled, a shift operation to another gear stage is performed or until the engine speed increases to a predetermined value (Ne1 exceeding the mesh torque cut region in FIG. 3) or higher. During this time, a function for limiting restart of torque cut control is provided.
[0026]
FIG. 4 is a flowchart for explaining torque cut control. In Step 1, whether the transmission 3 is in a specific gear stage, in Step 2, the torque cut permission plug is “1”, or in Step 3, the accelerator opening is 90%. As described above, in step 4, it is sequentially determined whether the running acceleration of the vehicle is a1 or more. If all of these are yes, the process proceeds to step 5. In step 5 to step 7, in order to warn the start of torque cut control, the buzzer 13A is operated for a predetermined time t1 seconds, and then engine control according to the torque curve TL in FIG. 3 is executed. At the same time, the torque cut display lamp 13B is turned on at step 8, and the torque cut flag is set to "1" at step 9.
[0027]
When at least one of step 1 to step 4 is no, the process proceeds to step 10. In steps 10 and 11, the torque cut permission flag is set to “0”, and normal engine control according to the torque curve TH of FIG. 3 is executed. At the same time, in step 12, the torque cut display lamp 13B is turned off. In Steps 13 to 15, when the torque cut flag is “1”, the buzzer 13A is operated for a predetermined time t2 seconds to warn the release of the torque cut control, and then the torque cut flag is set to “0”. To.
[0028]
In step 16, it is sequentially determined whether the vehicle speed change operation has been performed or in step 17 whether the engine speed is Ne1 or higher in FIG. 3. If at least one of these is yes, in step 18, the torque cut permission flag is set to “ Set to 1 ”.
[0029]
With such a configuration, torque cut control is performed when the load on the vehicle is small and the driving force has a margin, and part of the fuel injection amount is saved. When the load on the vehicle increases due to the load amount of the vehicle or the road conditions, normal engine control is performed, so that driving force is ensured. That is, the fuel efficiency can be improved without impairing the driving operability of the vehicle.
[0030]
The engine torque cut does not depend on the driver's operation, but is automatically performed when a predetermined permission condition is satisfied, and the return to normal engine control is also performed automatically. Since the alarm buzzer 13A is activated at the time of starting and releasing the torque cut control, it is possible to alert the driver. Therefore, the driver is not confused by unexpected torque down and torque up. Further, during the torque cut operation, it can be easily confirmed by turning on the torque cut display lamp 13B.
[0031]
Note that a low speed stage and a reverse stage may be set as the specific gear stage. In these gear stages having a deep gear ratio, when there is a margin in driving force, the excessive torque is cut to improve the durability and reliability of the transmission.
[0032]
FIG. 5 is a flowchart for explaining another embodiment. A torque cut switch (31 in FIG. 1) for arbitrarily selecting torque cut control by the driver is provided. In step 1, the switch state is determined. It has become. When the torque cut switch 31 is on, the process proceeds to step 2, and when the torque cut switch 31 is not on, the control operation from step 2 to step 19 is passed. Since the control operations from Step 2 to Step 19 are the same as Step 1 to Step 18 in FIG.
[0033]
According to this, on / off of torque cut control can be arbitrarily selected. When the torque cut control is turned off, the engine torque cut is not automatically performed during this period even if the vehicle load or road conditions change. That is, only when the torque cut control is turned on, the torque cut operation is automatically controlled according to the load amount of the vehicle, the road condition, and the like.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.
FIG. 2 is a block diagram similarly relating to torque cut control.
FIG. 3 is also a torque cut characteristic diagram of the engine.
FIG. 4 is a flowchart that similarly illustrates torque cut control.
FIG. 5 is a flowchart illustrating torque cut control as another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1A Governor apparatus of fuel injection pump 2A Clutch booster 3A Gear shift unit 11 Transmission control unit 11A Vehicle acceleration calculation means 12 Engine control unit 12A Engine control means 12B, 12C Engine torque characteristic memory 13A Alarm buzzer 13B Display lamp during torque cut 21 Vehicle speed sensor 28 Accelerator opening sensor 29 Engine rotation sensor 30 Gear position sensor 31 Torque cut switch

Claims (4)

When the condition that the transmission is in a specific gear stage, the torque cut permission flag is “1”, the accelerator opening is at a predetermined value or more and the vehicle running acceleration is at a predetermined value or more is satisfied, the torque curve of normal engine control is Means for performing torque cut control using a torque curve that cuts a part, the transmission is in a specific gear stage, the torque cut permission flag is “1”, the accelerator opening is stepped on more than a predetermined value, and the vehicle running acceleration is predetermined When the condition exceeding the value is broken, the engine is controlled so that the torque cut control is canceled and the normal torque curve is used and the torque cut permission flag is set to “0”, the speed change operation of the vehicle is performed, the engine speed Is set to a torque cut permission flag “ Means to "that was the provided the engine output torque limiting device according to claim. 2. The engine output torque limiting device according to claim 1, further comprising means for selecting on / off of torque cut control based on a manual operation . The engine output torque limiting device according to claim 1, further comprising means for operating an alarm in the cab at least at the start of torque cut control . 2. The engine output torque limiting device according to claim 1, further comprising means for displaying in a cab that torque cut control is being performed .

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