JPH0139507B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a device for controlling creep torque of an automatic transmission so as to maintain a stopped state of a vehicle on an uphill road by using the creep torque of an automatic transmission. (Prior art) Automatic transmissions are equipped with a torque converter in their power transmission system, so they are capable of changing the driving range, that is, forward automatic transmission driving.
(D) range, 2nd gear engine brake running ( ) range or 1st gear engine braking running ( ) range, and in these ranges, power can be transmitted by a friction element (usually a rear clutch) that continues to operate regardless of the gear position. Even if the vehicle is stopped, the vehicle can be stopped as long as the engine is kept idling. However, the torque converter cannot reduce the transmitted torque to zero, and if the brake is left inactive, a so-called creep phenomenon occurs in which the vehicle moves forward at a slow speed in the above-mentioned driving range. In order to eliminate this creep phenomenon, a creep prevention device has been proposed that puts the frictional elements into a non-operating state, but on the other hand, the creep torque that causes this phenomenon is useful for keeping the vehicle stopped on an uphill road. In fact, a technique as shown in Japanese Patent Application Laid-open No. 103958/1983 has been proposed. This technology prevents creep by keeping the friction element inactive when the vehicle is stopped in the driving range, except when going uphill.
On an uphill road, the friction elements are completely coupled (creep prevention is stopped) to utilize creep torque to prevent the vehicle from rapidly retreating. (Problem to be solved by the invention) However, with this technology, the vehicle cannot be stopped on a steep slope where the vehicle would move backwards due to the creep torque when the creep prevention is released, and the driver cannot There is a cumbersome operation in which the engine speed must be increased by pressing the accelerator pedal to increase the creep torque until it balances with the reverse torque. (Means for Solving the Problems) In order to eliminate such inconveniences, the present invention proposes a device that automatically increases the engine speed and controls the creep torque. , in a vehicle driven by power from an engine 1 via an automatic transmission 2 as shown in FIG.
A road slope sensor 3 detects a road slope; an engine speed setting means 4 sets a target rotation speed of the engine 1 that generates a creep torque that balances the backward torque according to the road slope; It is provided with an engine rotation speed detection means 5 for detecting the engine rotation speed, and an idle rotation speed control means 6 for controlling the engine 1 so that the actual rotation speed becomes the target rotation speed. (Function) The idle speed control means 6 idle-controls the engine 1 so that the engine speed detected by the means 5 becomes the target speed set by the means 4. Therefore, the creep torque of the automatic transmission 2 is balanced with the reverse torque depending on the road surface slope, and the vehicle can be automatically maintained in a stopped state without accelerator operation on a steeply ascending road. (Example) Hereinafter, an example of the present invention will be described in detail based on the drawings. FIG. 2 shows an embodiment of the present invention, in which 10 is a torque converter, 11 is a clutch as a friction element that continues to operate hydraulically in the travel (D,...) range of the automatic transmission, and 12 is an engine. .
The torque converter 10 includes a pump impeller (input element) 10a driven by the crankshaft 12a of the engine 12, a turbine runner (output element) 10b fluid-driven by the pump impeller 10a, and a reaction force to the driving fluid to increase the torque of the turbine runner. The stator (reaction force element) 10c is drivingly coupled to a turbine runner 10b and a torque converter output shaft (input shaft of the clutch 11) 13.
Clutch 11 is actuated by hydraulic pressure P _C
3 is connected to the clutch output shaft 14 to enable the automatic transmission to transmit power in the first gear position, and the automatic transmission selects another gear position by a combination of this clutch operation and the operation of other friction elements. can do. The clutch operating oil pressure P _C is generated in the circuit 16 using the line pressure P _L supplied to the circuit 15 only in the travel (D, ...) range of the automatic transmission as the source pressure,
Circuits 15 and 16 to control this working oil pressure P _C
A pressure regulating valve 17 is inserted between them. The pressure regulating valve 17 includes a spool 17a, whose upper end surface in the figure is connected to a chamber 17b.
In addition, the lower end faces face the chambers 17c, and the spool 17a is elastically supported in the left half position in the figure by a spring 17d. Then, the chamber 17b is connected to the circuit 15 by the branch path 18, and the chamber 17c is connected to the circuit 16 by the branch path 19.
A drain port 20 is opened and installed in the middle of the branch path 18. A solenoid 21 is provided opposite to the drain port 20, and this solenoid normally opens the drain port 20 when the plunger 21a is in the retracted position on the left half in the figure, and when energized, the plunger 21a opens.
is the protruding position on the right half of the figure, and the drain port 20
shall be closed. The solenoid 21 is driven at a constant frequency (for example, 50 Hz), and the average opening degree of the drain port 20 is controlled by changing the ratio (duty) D of the driving time width to one cycle.
When duty D=0%, the control pressure in chamber 17b is 0.
As the duty D increases, the control pressure also increases, and reaches a maximum value corresponding to the line pressure P _L when the duty D is 100%. When the control pressure is 0, the spool 17a is spring 1.
7d, the spool 17a is placed in the left half position in the figure, connecting the circuit 15 to the drain port 22 and cutting it off from the circuit 16, and as the control pressure increases, the spool 17a descends in the figure, gradually increasing the communication of the circuit 15 with the circuit 16. At the same time, communication with the drain port 22 is gradually reduced,
At the maximum value of the control pressure, the spool 7a is in the right half position in the figure, cutting off the circuit 15 from the drain port 22 and allowing it to communicate only with the circuit 16. Thus, since the control pressure changes depending on the duty D, the change characteristic of the working oil pressure P _C with respect to this duty is as shown in FIG. The engine 12 takes in air in the directions of arrows a and b through the intake pipe 24 according to the opening degree of the throttle valve 23, and ignites and burns this air, fuel from a fuel injection valve (not shown), and a mixture. The engine 1 is operated by adding the following system to the intake pipe 24.
Controls the idle speed of 2. That is, the intake pipe 2
4 is provided with an auxiliary air passage 25 that bypasses the throttle valve 23 so that air is sucked in as shown by arrow C when the throttle valve 23 is fully closed. Insert. This control valve 26 has a diaphragm chamber 26a.
As the control negative pressure inside increases, the degree of opening is reduced to reduce the amount of auxiliary air, and the idle speed of the engine 12 can be lowered. The control negative pressure is generated by a negative pressure control valve 27, and this control valve 27 has a diaphragm constant pressure valve section 28 that keeps the engine intake negative pressure in the intake pipe 24 constant and stores it in the chamber 27a, and a diaphragm constant pressure valve part 28 that keeps the engine suction negative pressure in the intake pipe 24 constant and stores it in the chamber 27a, and converts this stored negative pressure into atmospheric pressure. Introductory pipe 29
It consists of a solenoid valve 30 that dilutes the water by atmospheric pressure. It is assumed that the solenoid valve 30 normally remains closed so as not to perform any of the above dilution, and when energized opens to perform the above dilution. The solenoid valve 30 is driven at a constant frequency,
Ratio of driving time width to one cycle (duty)
The degree of dilution is controlled by changing DA. Therefore, when the duty DA is 0%, the controlled negative pressure in the chamber 26a is as indicated by the solid line α in FIG.
It has the same maximum value as the stored negative pressure in 7a, and as the duty DA increases, the control negative pressure decreases as shown by the solid line. Then, at the highest value of the control negative pressure, the auxiliary air amount control valve 26 is fully closed to reduce the amount of auxiliary air passing through the passage 25 to 0, and as the control negative pressure decreases, the control valve 26
The opening degree is increased to gradually increase the amount of auxiliary air as indicated by the dashed line β in FIG. Therefore, duty DA
The idle speed of the engine 12 increases due to an increase in DA, and the idle speed of the engine 12 increases due to a decrease in duty DA.
The idle speed of the engine will decrease. The duty control of the solenoid 21 and the duty control of the solenoid valve 30 are performed by the controller 3.
1, and this controller includes a central processing unit (CPU) 32, a random access memory (RAM) 33, and a read-only memory (ROM).
34, an input interface circuit 35, and an output interface circuit 36. This controller 31 receives a signal from a turbine rotation sensor 37 that detects the rotation speed of the turbine runner 10b (torque converter output rotation speed) N _T , a signal L from a range switch 38 that is turned ON in the forward running range, and a signal L from the range switch 38 that is turned ON in the forward running range. A signal from the throttle opening sensor 39 that detects the throttle opening degree (opening degree of the throttle valve 23) TH of the engine 12, a signal from the engine rotation sensor 40 that detects the rotational speed N _E of the engine 12, and an automatic transmission. A signal from a vehicle speed sensor 41 that detects the output rotation speed (vehicle speed) V, a signal from a road slope sensor 42 that detects the road slope θ,
A signal from a water temperature sensor 43 that detects the cooling water temperature T of the engine 12 is input, and based on this input information, the control program shown in FIG. 3 is executed to perform duty control of the solenoid 21 and duty control of the solenoid valve 30. shall be. The control program in Figure 3 is executed for a certain period of time (for example, 10
In this periodic interrupt routine, which is executed by interrupting the main routine for speed change control of the automatic transmission every (msec), the selected range of the automatic transmission performs the creep torque control according to the present invention from the range signal L in step 50. Determine whether or not the vehicle is in the desired driving (D,...) range, and park outside of these ranges (P).
range, reverse travel (R) range, or neutral (N) range, the throttle opening TH is set in step 51.
From this, it is determined whether the engine is idling with the throttle valve 23 fully closed. If the engine is not idling, the main routine is returned to in step 52. If the engine is idling, the engine speed N _E is read in step 53, and then the control proceeds to step 54 to calculate the idling speed as follows. control. That is, in step 54, the engine cooling water temperature T is read, and in the next step 55, the target idle rotation speed N _R set for each water temperature T is looked up as a table, and the control proceeds to step 56. In step 56, the same determination as in step 50 is made, but since it has been determined in step 50 that a range other than the travel range is being selected, the control proceeds to step 57, where the engine speed N _E has reached the target idle. Determine whether or not the rotation speed is greater than or equal to the rotation speed N _R. If N _E ≧ N _R , in step 58, the integral correction amount obtained by multiplying the rotational speed error (N _E − N _R ) by the integral constant K _i is used as the previous duty DA (OLD).
Calculate the integral correction duty DA (NEW) by subtracting it from
It is determined by the calculation DA(NEW)-k _p (N _E -N _R ) (where k _p is a proportionality constant), and this is updated in step 60. Thus, the duty DA is decreased by an amount equal to the error N _E −N _R multiplied by the proportionality constant k _p and the integral constant k _i , and by outputting this duty DA to the solenoid valve 30 in step 61, the sixth As is clear from the characteristic β in the figure, the engine speed N _E can be lowered to approach the target idle speed N _R by reducing the amount of auxiliary air. Conversely, if N _E < N _R , step 62 and 63
Calculations are performed in the opposite direction to those in steps 58 and 59 to increase the duty, and the duty value DA is updated in step 60 and outputted to the solenoid 30 in step 61. As a result, as is clear from the characteristic β in FIG. 6, the amount of auxiliary air is increased, and the engine speed N _E can be raised to approach the target idle speed _NR . As a result of the above, the target idle rotation speed obtained by table searching the engine rotation speed N _E during idling operation outside the driving range in step 55.
This means that it can be maintained at N _R. If it is determined in step 50 that the vehicle is in the driving range (D,...) that requires the creep torque control according to the present invention, the control proceeds to step 64, where the vehicle speed V is either traveling at a minute set value V _C or more or less than V _L. If the vehicle is stopped, the duty D is set to 100% in step 65, the duty is updated in step 66, and the duty D is set to 100% in step 61.
% is output to the solenoid 21. This duty
100% means that the pressure regulating valve 17 changes the operating oil pressure P _C to the line pressure P _L via the solenoid 21, as is clear from Fig. 5.
The clutch 11 is then fully engaged and allows the vehicle to drive normally. step
If it is determined in step 64 that the vehicle is stopped, it is determined in step 67 whether or not the engine is idling with the throttle opening TH fully closed, that is, whether or not the vehicle does not desire to start due to the stopped state, and it is determined that the vehicle desires to start. If so, set duty D to 100% in steps 68 and 69.
In step 70, the duty is updated while increasing by α% until it becomes .Then, in step 61, the updated duty is output to the solenoid 21. By increasing the duty D, the hydraulic pressure P _C is gradually increased as shown in FIG. 5, and the clutch 11 can be engaged to start the vehicle. Since the duty D is increased by .alpha.%, the clutch 11 is engaged slowly and the start is performed without a start shock. If it is determined in step 67 that the vehicle is in a stopped state in which starting is not desired, the control proceeds to step 71, where the road surface slope θ is determined to be such that the vehicle will move backward unless creep torque control is performed using the idle speed increase control of the present invention. It is determined whether or not the road surface gradient setting value θ _E is greater than or equal to the road surface gradient setting value θ E. If θ<θ _E , the engine rotation speed (torque converter input rotation speed) N _E is read in step 72, and the torque is calculated from the engine rotation speed N _E and road surface slope θ based on the table data shown in the following table in the next step 73. The target slip amount (target flip torque) Rij of the converter 10 is looked up as a table.

[Table] Note that this target slip amount R _ij is determined so that the target creep torque determined by this slip amount is in balance with the backward torque of the vehicle depending on the road surface slope θ. Therefore, the target slip amount
Of course, if R _ij differs depending on whether the engine speed N _E (idling speed) is being warmed up or not, it is of course necessary to set R ij by making corrections accordingly. In the next step 74, the input/output rotation difference N _E - N _T of the torque converter 10, that is, the actual slip amount ΔN of the torque converter ΔN = N _E - N _T (actual creep torque), is calculated, and in step 75, this actual creep torque is calculated. It is determined whether ΔN is greater than or equal to the target creep torque _Rij . When ΔN≧R _ij , that is, when the actual creep torque is higher than the target creep torque and the vehicle moves forward at a slow speed, the integral correction amount obtained by multiplying the error (ΔN−R _ij ) by the integral constant k _i is calculated in step 76. The integral correction duty D (NEW) is calculated by subtracting it from the previous duty D (OLD), and in step 77, the current duty D is calculated as D (NEW) - k _p (ΔN - R _ij ) (where k _p is proportional). This is updated in step 78, and the solenoid 2 is updated in step 61.
Output to 1. In this way, the duty D is reduced by the amount obtained by multiplying the error (ΔN-R _ij ) by the integral constant K _i and the proportionality constant K _p , and as is clear from _FIG . (fastening force)
can be reduced so that the actual creep torque approaches the target creep torque. vice versa,
If ΔN<R _ij , that is, if the actual creep torque is less than the target creep torque and the vehicle moves backwards, in steps 79 and 80, calculations are performed in the direction of increasing the duty, which is the opposite of those in steps 76 and 77, and the calculated value is D is updated in step 78 and output to the solenoid 21 in step 61. Thus, as is clear from FIG. 5, the hydraulic pressure P _C (clamping force of the clutch 11) is increased, and the actual creep torque can be increased to approach the target creep torque. As described above, the actual creep torque is maintained at the target creep torque, and the creep phenomenon can be prevented regardless of the road surface slope θ, and the vehicle can be prevented from retreating on an uphill road. During this time, step 56 selects step 81, but since θ≧ _θE , step 81 selects step 57, so the normal idle rotation control is continued, and the idling rotation speed of the engine 12 changes at each water temperature T. The target rotation speed is maintained. By the way, under such idle rotation control, even if the engagement force of the clutch 11 is controlled alone, that is, even when the clutch 11 is fully engaged and the creep torque is maximized, on a steep slope where the vehicle is moving backwards, Step 71 determines that θ≧ _θE , and the control proceeds to step 82, where the duty D is set to 100% and
This is updated in step 78 and outputted to the solenoid 21 in step 61, whereby the clutch 11 is fully engaged and the creep torque is brought to its maximum value. Thereafter, the creep torque control according to the present invention is performed as follows to maintain the vehicle stopped on the steeply ascending slope. That is, in this case, step 56 selects step 81, and step 81 sequentially selects step 83. In step 83, the road surface gradient θ is read, and in the next step 84, the engine speed is set to a target value (with the clutch 11 in a fully engaged state) such that a creep torque that balances the reverse torque corresponding to the road surface gradient θ is obtained. Correct the idle speed N _R. For this correction, the correction amount ΔN _R set for each road surface gradient θ (where θ≧θ _E ) is added to the target idle rotation speed N _R retrieved from the table in step 55. Then the control steps
After 57, idle rotation control is executed, but in this case, since the target idle rotation speed is the above correction value, the engine rotation speed is maintained at this correction value. Therefore, when the clutch 11 is fully engaged, the creep torque increases by the amount _ΔNR of the increase in the idle speed, and this balances out with the reverse torque corresponding to the road surface gradient of the steeply ascending road, and in this case as well, It can be prevented. FIG. 4 shows another example of the control program. In this example, the determination as to whether or not the road is steeply climbing requires the creep torque control (idle rotation control) according to the present invention, in steps 71 and 81 in FIG. Another step 85,
86. This is because the step
A step 87 is inserted between 67 and 72 to read the road surface gradient θ, and this is used in step 73. Then, step 85 is inserted between steps 73 and 74, and the maximum slip amount R _F (maximum creep torque ) and the target slip amount R _ij (target creep torque). Here, if R _ij > R _F , the vehicle is climbing a steep slope where the vehicle will retreat even with the maximum creep torque, so the idle rotation control according to the present invention is necessary and the control is advanced to step 82, and if R _ij ≦ R _F
If so, the road slope is such that it is possible to prevent the vehicle from moving backwards by simply executing steps 74 to 80, so the control is
Make it possible to proceed to 74. Also, in response to the above-mentioned change, step 86 was inserted between steps 56 and 83 in place of step 81 in FIG.
On a steeply ascending slope where R _ij > R _F , the control can be advanced to step 83 to perform the idle rotation control according to the present invention, and for a road surface slope lower than that, the control can be advanced to step 57 to perform the normal idle rotation control. can. (Effects of the Invention) Thus, as described above, the creep torque control device of the present invention is configured to control the idle rotation of the engine so that the engine rotation speed becomes the target rotation speed that generates the creep torque that balances the backward torque according to the road slope. This makes it possible to balance the automatic transmission's creep torque with the reverse torque according to the road surface slope, and it is possible to automatically hold the vehicle in a stopped state on steep slopes without accelerating the vehicle, reducing operational hassles. It becomes possible to eliminate the discomfort.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of the creep torque control device of the present invention, FIG. 2 is a system diagram showing an embodiment of the device of the present invention, and FIGS. 3 and 4 respectively show the control program executed by the controller in the same device. Flowcharts showing two examples, FIG. 5 is a characteristic diagram of changes in clutch operating oil pressure with respect to duty, and FIG. 6 is a characteristic diagram of changes in control negative pressure and auxiliary air amount with respect to duty. 1, 12...Engine, 2...Automatic transmission,
3, 42...Road surface gradient sensor, 4...Engine rotation speed setting means, 5...Engine rotation speed detection means,
6... Idle rotation speed control means, 10... Torque converter, 11... Clutch, 13... Torque converter output shaft, 14... Clutch output shaft, 1
5... Line pressure circuit, 16... Clutch operating hydraulic circuit, 17... Pressure regulating valve, 20, 22... Drain port, 21... Solenoid, 23... Throttle valve, 24... Intake pipe, 25... Auxiliary air passage, 26... Auxiliary air amount control valve, 27... Negative pressure control valve, 28... Constant pressure valve section, 30... Solenoid valve, 31... Controller, 37... Turbine rotation sensor, 38... Range Switch, 39...
Throttle opening sensor, 40...engine rotation sensor, 41...vehicle speed sensor, 42...road surface gradient sensor, 43...water temperature sensor.

Claims (1)

[Scope of Claims] 1. In a vehicle that is driven by power from an engine via an automatic transmission, there is provided a road slope sensor that detects a road slope, and an engine that generates creep torque that balances reverse torque according to the road slope. An engine rotation speed setting means for setting a target rotation speed, an engine rotation speed detection means for detecting the actual rotation speed of the engine, and an idle rotation speed control means for controlling the engine so that the actual rotation speed becomes the target rotation speed. A creep torque control device for an automatic transmission, which is characterized by: