JP4994794B2 - Vehicle cruise control device - Google Patents

Description

  The present invention relates to a cruise control device for a vehicle that performs engine control and shift control so as to maintain a vehicle speed set by a driver.

  Generally, this type of cruise control device detects the difference (speed difference) between the vehicle speed set by the driver and the actual vehicle speed (actual vehicle speed), and based on this speed difference, the engine output and the shift of the automatic transmission. The speed (speed ratio) is controlled so that the actual vehicle speed converges to the target vehicle speed. For example, if the vehicle speed reaches a road surface with a large traveling load such as an uphill road during cruise control, the vehicle speed temporarily decreases. Therefore, the throttle valve opening is increased by engine control to increase the engine output. On the other hand, in the shift control, when the throttle valve opening is greatly opened during traveling on an uphill road or the like, the shift control means controls the downshift of the transmission so that the actual vehicle speed becomes the set vehicle speed.

  For example, in Patent Document 1 (Japanese Patent No. 3803461), during traveling by cruise control, the engine output is controlled based on the speed difference between the set vehicle speed and the actual vehicle speed, and the set vehicle speed at that time is maintained. Alternatively, it is determined whether or not a downshift of the transmission is necessary based on the travel load amount and the actual vehicle speed calculated based on the reference drive torque and the actual drive torque necessary to achieve the set vehicle speed, A technique for controlling the shift of the transmission based on this is disclosed.

According to the technique disclosed in this document, since the shift control during the traveling by the auto cruise control is performed based on the traveling load amount and the actual vehicle speed obtained from the reference driving torque and the actual driving torque, Even when the set vehicle speed cannot be maintained only by engine output control, the set vehicle speed can be easily maintained by quickly recovering the actual vehicle speed by early downshifting.
Japanese Patent No. 3803461

  Incidentally, in a normal automatic transmission, shift control is performed based on the accelerator opening and the vehicle speed operated by the driver. In this case, in the shift control in the automatic cruise control, a pseudo accelerator opening (hereinafter referred to as “pseudo accelerator opening”) is calculated from the required torque of the engine calculated based on the speed difference between the set vehicle speed and the actual vehicle speed. Then, by performing a downshift or an upshift based on the pseudo accelerator opening and the vehicle speed, the same shift control as the normal shift control can be performed.

  However, for some engines, the change in the engine torque T has a minute characteristic with respect to the change in the accelerator opening (= throttle opening). For example, as shown in FIG. 6, when the change amount of the engine torque T is very small (T1 to T2) with respect to the change amount of the accelerator opening θa [%] between θ1 and θ2, the engine request is required in this region. If the pseudo accelerator opening is calculated based on the torque, even if there is a slight change in the required torque, the accelerator opening will change greatly.Therefore, in auto cruise control, excessive kickdown or upshift is performed. For example, there is an inconvenience that shift control contrary to the driver's intention is performed.

  In view of the above circumstances, the present invention calculates the pseudo accelerator opening from the required torque of the engine, and even when performing shift control during traveling by cruise control based on the pseudo accelerator opening and the vehicle speed, It is an object of the present invention to provide a cruise control device for a vehicle that can perform gear shifting control in accordance with the driver's intention without causing any kickdown and upshift.

In order to achieve the above object, a vehicle cruise control apparatus according to the present invention includes an engine control means for controlling an engine based on at least an accelerator opening, and a request for converging an actual vehicle speed to a cruise control target vehicle speed that is a target vehicle speed in the cruise control apparatus. Torque is obtained, a target throttle opening corresponding to the required torque is set and output to the engine control means, and a cruise control required accelerator opening which is an accelerator opening required by the cruise control device is set based on the required torque. The cruise control device for a vehicle includes: cruise control means for outputting to the engine control means; and shift control means for performing shift downshift or upshift shift control of the transmission based on the cruise control required accelerator opening and vehicle speed. At the cruise con Roll means, from the low gear ratio toward a high vehicle speed operation from the middle vehicle speed is set to a value that restricts the shift control of the high-speed ratio side f the gear ratio changes largely compared to the gear ratio of the low gear ratio has a high threshold, as compared to the pseudo accelerator opening calculated based on the required torque and the upper threshold, the upper limit when該疑similar accelerator opening is greater than the upper threshold value A threshold is set to the cruise control required accelerator opening, and when the pseudo accelerator opening is lower than an upper limit threshold, the pseudo accelerator opening is set to the cruise control required accelerator opening.

  According to the present invention, the cruise control required accelerator opening that is output to the shift control means is the value that is regulated by the upper limit threshold value. Therefore, the pseudo accelerator opening is calculated from the engine required torque, and this pseudo accelerator opening is calculated. Even if shifting control during traveling by cruise control is performed based on the accelerator opening and the vehicle speed, there is no excessive kickdown and upshifting, and shifting according to the driver's intention Control can be performed.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration diagram of the engine control apparatus.

  Reference numeral 1 in FIG. 1 denotes an engine, and an automatic transmission 3 is connected to the output side of the engine 1 via a torque converter 2. The output from the engine 1 is transmitted to the automatic transmission 3 via the fluid of the torque converter 2 or a lock-up clutch provided in the torque converter 2, and the automatic transmission 3 uses a predetermined gear (gear ratio). ), The power is transmitted from the output shaft 4 to the drive wheels such as the rear wheels or the front wheels. Note that the automatic transmission 3 according to this embodiment has five forward speeds.

  A throttle valve 6 is interposed in the intake passage 5 communicating with an intake port (not shown) of the engine 1. The throttle valve 6 is connected to a throttle motor 8 composed of a stepping motor or the like, and the throttle motor 8 is driven by a drive signal output from an engine control unit 23 described later, so that the valve opening angle of the throttle valve 6 is increased. To control.

  Further, the automatic transmission 3 is provided with a transmission mechanism constituted by planetary gears and the like, and a control valve 11 for selectively switching the shift speed (transmission ratio) of the transmission mechanism. The control valve 11 is switched by a shift signal from a shift control unit 24 described later.

  Reference numeral 21 denotes an electronic control unit (ECU) that controls the running state of the vehicle, and is mainly composed of a microcomputer including a well-known CPU, ROM, RAM, and the like. The ECU 21 includes a function for controlling a traveling state during cruise control (hereinafter referred to as “crude control”), an auto cruise control unit 22 as cruise control means, an engine control part 23 as engine control means, and a shift control means. A shift control unit 24 is provided.

  When the cruise control operation switch 26 is turned on, the auto cruise control unit 22 detects the vehicle speed S [Km / h] detected by the vehicle speed detection means 27, the engine speed Ne [rpm] detected by the engine speed detection means 28, and the accelerator opening detection. Based on the accelerator opening θa [%] detected by the means 29, the target throttle opening θαs [deg] and the pseudo accelerator opening θha [%] are obtained, and the pseudo accelerator opening θha and the accelerator opening upper limit threshold are obtained. The cruise control required accelerator opening θas is obtained by comparing with the value θs. The vehicle speed detection means 27 includes a vehicle speed sensor and a wheel speed sensor. The wheel speed sensor detects the wheel speed of each wheel, and the average value of the wheel speed detected by each wheel speed sensor is the vehicle speed S. The engine speed detecting means 28 detects the speed of the output shaft of the engine and includes an engine speed sensor, a crank angle sensor, and the like.

  The engine control unit 23 drives the throttle motor 8 based on the target throttle opening θαs obtained by the auto cruise control unit 22 and performs feedback control so that the opening of the throttle valve 6 converges to the target throttle opening θαs.

  The shift control unit 24 performs shift control of downshift or upshift at a predetermined timing based on the cruise control required accelerator opening θas and the vehicle speed S obtained by the auto cruise control unit 22.

  As shown in FIG. 2, the auto cruise control unit 22 includes a cruise control target vehicle speed calculation unit 31, a driver required torque calculation unit 32, a cruise control required horsepower calculation unit 33, a cruise control required torque calculation unit 34, and a required torque selection calculation unit 35. A target throttle opening calculation unit 36, a pseudo accelerator opening calculation unit 37, a cruise control required accelerator opening calculation unit 38, and a cruise control required downshift calculation unit 39.

  Next, the process performed by each calculation part 31-39 which comprises the engine control part 23 is demonstrated.

  When the driver turns on the cruise control operation switch 26 disposed in the vicinity of a steering handle (not shown) while the vehicle is traveling, the vehicle is in the auto cruise mode, and the cruise control target vehicle speed calculation unit 31 sets the driver. The set vehicle speed (set vehicle speed) is set as the cruise control target vehicle speed So.

  The cruise control target vehicle speed So is read by the cruise control required horsepower calculating unit 33 and the cruise control required downshift calculating unit 39. The cruise control required horsepower calculation unit 33 is based on the speed difference ΔS (= So−S) between the cruise control target vehicle speed So and the actual vehicle speed (hereinafter referred to as “actual vehicle speed”) S detected by the vehicle speed detection means 27. The cruise control required horsepower HPs for causing S to reach the cruise control target vehicle speed So is obtained by a calculation formula or a table search.

  The cruise control required horsepower HPs is read by the cruise control required torque calculation unit 34. The cruise control required torque calculation unit 34 obtains the cruise control required torque Tcs from a calculation formula based on the cruise control required horsepower HPs and the engine speed Ne (Tcs = k · (HPs / Ne), where k is a coefficient).

  On the other hand, the driver request torque calculation unit 32 obtains the driver request torque Tacs by a calculation formula or a table search based on the accelerator opening θa that is the depression amount of the accelerator pedal detected by the accelerator opening detection means 29.

  The required torque selection calculation unit 35 compares the cruise control required torque Tcs with the driver required torque Tacs, and sets the higher one as the required torque Ts. Therefore, in a state where the driver releases the accelerator pedal, the cruise control required torque Tcs is set as the required torque Ts (Ts ← Tcs).

  This required torque Ts is read into the target throttle opening calculation unit 36 and the pseudo accelerator opening calculation unit 37. The target throttle opening calculation unit 36 obtains a target throttle opening θαs corresponding to the required torque Ts based on the required torque Ts, and outputs it to the engine control unit 23. On the other hand, the pseudo accelerator opening calculation unit 37 calculates the pseudo accelerator opening θha from the required torque Ts by back calculation.

  The pseudo accelerator opening θha is read by the cruise control required accelerator opening calculation unit 38. The cruise control required accelerator opening calculation unit 38 compares the pseudo accelerator opening θha and the accelerator opening upper limit threshold θs, and when θha ≦ θs, sets the pseudo accelerator opening θha to the cruise control required accelerator opening θas. (Θas ← θha) and output to the shift control unit 24. When θha> θs, the accelerator opening upper limit threshold θs is set to the cruise control required accelerator opening θas (θas ← θs), and is output to the shift control unit 24.

  The accelerator opening upper limit threshold value θs is set by a table search based on the vehicle speed S. FIG. 3 shows an accelerator opening upper limit threshold value table. In the figure, for the sake of convenience of explanation, downshift (line indicated by a solid line) and upshift (line indicated by a broken line) are also shown. As shown in FIG. 6 described above, depending on the engine, there is a region where the change in the engine torque T (between T1 and T2) is minute compared to the change in the accelerator opening θa (between θ1 and θ2). Since the pseudo accelerator opening θha is set based on the required torque Ts, when the required torque Ts is between T1 and T2 in FIG. 3, even if the change in the required torque Ts is small, the pseudo accelerator opening θha Changes significantly. As a result, not only excessive kickdown or upshift is performed, but also control hunting in which downshift and upshift are repeated occurs.

  On the other hand, even if the pseudo accelerator opening θha fluctuates greatly, the upper limit of the change in the pseudo accelerator opening θha is controlled by restricting the upper limit of the pseudo accelerator opening θha with the accelerator opening upper limit threshold θs as in this embodiment. Since it is regulated according to the vehicle speed S, it is possible to prevent excessive kick down or up shift in the shift control unit 24. Since excessive kickdown appears as a large shift shock, as shown in FIG. 3, the accelerator opening upper limit threshold value θs according to the present embodiment is from a medium vehicle speed (for example, around 50 [Km / h]) to a high vehicle speed. It is set between a downshift line from the fifth speed to the fourth speed, an upshift line from the fourth speed to the fifth speed, and a downshift line from the fourth speed to the third speed.

  Therefore, for example, when the vehicle is traveling at a vehicle speed of 80 [Km / h], if the pseudo accelerator opening θha is set to 70 [%] higher than the accelerator opening upper limit threshold θs, the accelerator opening upper limit threshold is set. In the state where there is no value θs, the shift control unit 24 downshifts from the fifth gear having a high gear ratio and having a low gear ratio to the third gear having a relatively high gear ratio compared to the gear ratio of the fifth gear. I feel a strong shift shock. However, in this embodiment, as described above, the accelerator opening upper limit threshold value θs is set between the downshift line from the fifth speed to the fourth speed and the downshift line from the fourth speed to the third speed. Therefore, at a vehicle speed S higher than the medium vehicle speed (for example, around 50 [Km / h]), it is not downshifted to the third speed. Therefore, in this region, only a downshift from the fifth speed to the fourth speed is allowed, so that a strong shift shock is not felt and shift control is performed in accordance with the driver's intention. Further, since the cruise control required accelerator opening degree θas is regulated by the accelerator opening upper limit threshold value θs, even if the pseudo accelerator opening degree θha greatly fluctuates with respect to a minute change in the required torque Ts, Unnecessary shift control such as repeated shifts and upshifts is not performed, and control hunting can be satisfactorily prevented.

  On the other hand, when starting acceleration from the first speed, when the pseudo accelerator opening θha suddenly becomes a large value and exceeds the accelerator opening upper limit threshold θs, the cruise control required accelerator opening θas becomes the accelerator opening upper limit threshold. Since it is limited by θs, the upshift instruction signal is output early at a relatively low vehicle speed (near 40 [Km / h]), so that an excessive feeling of acceleration is not given to the driver.

  The cruise control required downshift calculation unit 39 obtains an acceleration determination threshold Gs by referring to the speed difference table based on the speed difference ΔS (= So−S) between the cruise control target vehicle speed So and the actual vehicle speed S. Then, the actual acceleration G, which is the actual acceleration, is compared with the acceleration determination threshold value Gs. When G ≦ Gs, it is determined that the actual vehicle speed S during acceleration causes an undershoot, and the shift control unit A downshift request signal is output to 24. As a result, the shift control unit 24 outputs a downshift instruction signal and prevents undershoot of the vehicle speed S.

  FIG. 4 illustrates the characteristics of the speed difference table. As shown in the figure, in the speed difference table, an acceleration determination threshold value Gs having a larger value is set as the speed difference ΔS increases. A region where the acceleration determination threshold Gs is a negative value is a region where no downshift is required.

  As shown in FIG. 5 (a), for example, when a torque shortage occurs while the vehicle is traveling uphill, and the actual vehicle speed S becomes lower than the cruise control target vehicle speed So, the pseudo accelerator opening θha becomes equal to the cruise control target vehicle speed So. Therefore, the vehicle is accelerated to the cruise control target vehicle speed So. However, since the pseudo accelerator opening degree θha is regulated by the accelerator opening upper limit threshold value θs, when there is no cruise control down request by the cruise control demand downshift calculation unit 39, the load increases during a sudden climbing uphill. However, the downshift instruction signal is not output from the speed change control unit 24, the torque shortage is not resolved, and an undershoot of the vehicle speed S occurs.

  In the present embodiment, when the actual vehicle speed S is equal to or less than the cruise control target vehicle speed So and the speed difference ΔS is equal to or less than the acceleration determination threshold value Gs, a downshift request signal is output to the shift control unit 24. Undershoot of the actual vehicle speed S is prevented, and acceleration in accordance with the driver's intention can be obtained.

  FIG. 5B shows the shift control in the uphill traveling. For example, if the preceding vehicle deviates from the course while following the preceding vehicle, the vehicle gradually controls the target vehicle speed closer to the set vehicle speed in order to perform constant speed driving at the set vehicle speed. Even if the opening degree θha is set to a large value, the upper limit thereof is restricted by the accelerator opening upper limit threshold value θs. Therefore, when there is no cruise control down request by the cruise control demand downshift calculation unit 39, the acceleration is insufficient. Become. In the present embodiment, when the actual vehicle speed S is relatively lower than the cruise control target vehicle speed So and the speed difference ΔS is equal to or less than the acceleration determination threshold value Gs, a downshift instruction is given to the shift control unit 24. Since a signal is output, good acceleration performance can be obtained.

  Thus, according to this embodiment, since the upper limit of the pseudo accelerator opening θha is regulated by the accelerator opening upper limit threshold θs, the pseudo accelerator opening θha greatly fluctuates with respect to a minute change in the required torque Ts. Even in this case, it is possible to prevent an excessive kick-down or upshift. At that time, the engine control unit 23 feedback-controls the opening degree of the throttle valve 6 based on the target throttle opening degree θαs calculated by the auto cruise control part 22. Therefore, when adapting the feedback control of the torque calculation in the auto cruise control unit 22, since the shift control and the throttle control are separated and adapted, the opening degree of the throttle valve 6 is not limited and has a good output characteristic. Obtainable. As a result, even in the engine 1 as shown in FIG. 6, there is a region where the change in the engine torque T (between T1 and T2) is minute compared to the change in the accelerator opening θa (between θ1 and θ2). The output control of the engine 1 during traveling in the auto cruise mode and the shift control of the automatic transmission 3 are controlled in a state close to traveling by the driver's accelerator pedal operation, that is, in a state according to the driver's intention. And stable running performance can be obtained.

  Note that the present invention is not limited to the above-described embodiment. For example, the accelerator opening upper limit threshold value θs can be arbitrarily set, so that an automatic transmission having a gear position of 6th speed or more or 4th speed or less can be used. However, it is possible to set the optimum accelerator opening upper limit threshold value θs according to the characteristics of the mounted engine.

  Further, in the present embodiment, the target accelerator opening degree θas is set by comparing the pseudo accelerator opening degree θha and the accelerator opening upper limit threshold value θs in the auto cruise control unit 22, but the pseudo accelerator opening degree θha is The cruise control required accelerator opening θas may be set by comparing the accelerator opening upper limit threshold θs with the shift control unit 24.

  Further, the cruise control required downshift calculation unit 39 adds the gear position, the engine speed, and the vehicle speed in addition to the speed difference ΔS described above as a condition for outputting the downshift request signal, so that the gear position does not change for a predetermined time or more. In addition, a downshift request signal may be output when the engine speed and the vehicle speed are less than a predetermined threshold. By adding these conditions, it is possible to prevent the deterioration of the behavior due to the downshift.

Schematic configuration diagram of engine control device Functional block diagram showing the configuration of the auto cruise control unit Conceptual diagram of accelerator opening upper limit threshold table Conceptual diagram showing the characteristics of the speed difference table (A) is an explanatory view showing the speed difference between the target vehicle speed and the actual vehicle speed due to insufficient torque during uphill travel, and (b) is an explanatory view showing the speed difference between the target vehicle speed and the actual vehicle speed due to insufficient acceleration during uphill travel. Characteristic diagram showing the relationship between engine accelerator opening and engine torque

Explanation of symbols

1 ... Engine,
3 ... automatic transmission,
21 ... Electronic control unit,
22 ... Auto cruise control part,
23. Engine control unit,
24 ... transmission control unit,
26 ... cruise control switch,
27: Vehicle speed detection means,
28. Engine speed detecting means,
29 ... accelerator opening detection means,
31 ... cruise control target vehicle speed calculation unit,
32 ... Driver required torque calculation unit,
33 ... Crucone required horsepower calculation unit,
34 ... cruise control required torque calculation unit,
35 ... Requested torque selection calculation unit,
36: Target throttle opening calculation unit,
37 ... pseudo accelerator opening calculation unit,
38 ... cruise control required accelerator opening calculation unit,
39 ... cruise control request downshift calculation unit,
G ... acceleration,
Gs: acceleration determination threshold value,
HPs ... Crucon required horsepower,
Ne ... engine speed,
S ... Actual vehicle speed,
So ... cruise control target vehicle speed,
ΔS ... speed difference,
Tacs: Driver required torque,
Tcs: cruise control required torque,
Ts: Required torque θαs: Target throttle opening,
θa: accelerator opening,
θas: cruise control required accelerator opening,
θha: pseudo accelerator opening,
θs: accelerator opening upper limit threshold,

Claims (4)

Engine control means for controlling the engine based on at least the accelerator opening;
A required torque for converging the actual vehicle speed to a cruise control target vehicle speed that is a target vehicle speed in the cruise control device is obtained, a target throttle opening corresponding to the required torque is set and output to the engine control means, and based on the required torque Cruise control means for setting a cruise control required accelerator opening which is an accelerator opening required by the cruise control device and outputting the accelerator to the engine control means ;
A cruise control device for a vehicle, comprising: a shift control means for performing a shift control of a downshift or an upshift of the transmission based on the cruise control required accelerator opening and the vehicle speed ;
The cruise control means is set to a value that regulates the shift control from the low gear ratio from the medium vehicle speed to the high vehicle speed driving to the high gear ratio side where the gear ratio changes greatly compared to the gear ratio of the low gear ratio. The pseudo accelerator opening calculated based on the required torque is compared with the upper limit threshold, and when the pseudo accelerator opening is higher than the upper limit threshold, The upper limit threshold is set to the cruise control required accelerator opening, and when the pseudo accelerator opening is lower than the upper limit threshold, the pseudo accelerator opening is set to the cruise control required accelerator opening. Vehicle cruise control device. The upper threshold is, the cruise control apparatus for a vehicle according to claim 1 Symbol mounting, characterized in that it is variably set based on the actual vehicle speed. The cruise control means compares an acceleration determination threshold value with an actual acceleration, and outputs a downshift instruction signal to the shift control means when the actual acceleration is equal to or less than the acceleration determination threshold value. The cruise control device for a vehicle according to claim 1 or 2 . 4. The cruise control apparatus for a vehicle according to claim 3, wherein the acceleration determination threshold value is set based on a speed difference between the cruise control target vehicle speed and the actual vehicle speed.

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