JP2537066B2 - Shift control device for continuously variable transmission - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a shift control device in a belt type continuously variable transmission for a vehicle, which controls a shift speed based on a gear ratio and a rotation speed, and more particularly, to a correction control for performing a downshift according to a load state of an engine. .

[Prior art]

In this type of continuously variable transmission, when operating, for example, an air conditioner while the vehicle is traveling, it is calculated based on the rotational speeds of the primary pulley and the secondary pulley and the throttle opening degree according to the increase in load caused by the operation of the air conditioner. There is proposed a control in which the target gear ratio is changed and downshifted to compensate for the above-mentioned load increase. Regarding the shift control of the continuously variable transmission, as disclosed in, for example, Japanese Patent Application Laid-Open No. 59-200856, adjusting means for adjusting the continuously variable transmission ratio and driving the throttle valve are provided. A driving means is further provided, and further, an adjusting means capable of independently controlling both of the adjusting and driving means according to an accelerator operation amount is provided, and an external load is applied by the adjusting means in a region where the engine speed is equal to or lower than a set value. Then, there is a device in which the engine speed is increased.

[Problems to be Solved by the Invention]

By the way, in the shift control device disclosed in the above publication, the control gear that operates in response to an external load is used to drive the adjusting means for adjusting the continuously variable transmission ratio and the throttle valve. It has a complicated structure that requires a driving means and an adjusting means capable of controlling both the above-mentioned means independently, and is adapted to the running conditions of the vehicle simply by increasing the engine speed in response to an increase in external load. There is a problem that correction cannot be performed. The present invention has been made in order to solve such a problem, and by a simple control means configuration, when an external load is applied to a running vehicle, a stepless torque correction suitable for a running condition can be performed. An object of the present invention is to provide a shift control device for a transmission.

[Means for solving problems]

In order to achieve the above object, the present invention provides a gear shift control system in which a manipulated variable is determined and controlled by elements of a target value and an actual value based on a gear ratio, a target based on a target primary pulley rotation speed and a secondary pulley rotation speed. A means for correcting the target primary pulley rotation speed is provided in the process of calculating the gear ratio, and the target primary pulley rotation speed is limited by this correction means only when the engine torque is higher than the load / load torque. It is configured to make a correction corresponding to an increase in load caused by the above.

[Action]

Based on the above configuration, even if the load increases due to the operation of the air conditioner or the like while the vehicle is running, if the engine torque is small due to the load torque, correction is performed to downshift the gear ratio corresponding to the load increase. Therefore, unnecessary engine braking phenomenon does not occur.

【Example】

Embodiments of the present invention will be described below with reference to the drawings. Referring to FIG. 1, an overall structure of a drive system in which an electromagnetic clutch is combined with a belt type continuously variable transmission will be described. The engine 1 is connected to a continuously variable transmission 4 via an electromagnetic clutch 2 such as an electromagnetic powder type and a forward / reverse switching device 3 so that the continuously variable transmissions 4 to 1
The reduction gear 5, the output shaft 6, the differential gear 7 and the axle 8 of the set are transmitted to the drive wheels 9. The electromagnetic powder clutch 2 has a drive member 2a on the engine crankshaft 10 and a driven member 2b on the input shaft 11 having a clutch coil 2c. And clutch coil 2c
Electromagnetic powder is coupled and accumulated in a gap between the members 2a and 2b in a chain shape by a clutch current flowing therethrough, and clutch engagement / disengagement and clutch torque are variably controlled by the resulting coupling force. The forward / reverse switching device 3 is configured to be in a synchronous mesh type between the input shaft 11 and the transmission main shaft 12 by a gear, a hub, and a sleeve, and has at least a forward position where the input shaft 11 is directly connected to the main shaft 12 and an input shaft. And a retracted position where the rotation of 11 is reversed and transmitted to the main shaft 12. The continuously variable transmission 4 includes a main shaft 12 and an auxiliary shaft arranged in parallel with the main shaft 12.
The main shaft 12 is provided with a primary pulley 14 having a hydraulic cylinder 14a and a variable pulley spacing, and the auxiliary shaft 13 is similarly provided with a secondary pulley 15 having a hydraulic cylinder 15a. A drive belt 16 is wound around both pulleys 14 and 15, and both cylinders 14a and 15a are configured in a hydraulic control circuit 17. Then, a line pressure corresponding to the transmitted torque is supplied to both cylinders 14a and 15a to apply a pulley pressing force, and the primary pressure changes the ratio of the winding diameter of the drive belt 16 to the pulleys 14 and 15 to continuously change the speed. Is configured to control. Next, an electronic control system for the electromagnetic powder clutch 2 and the continuously variable transmission 4 will be described. Engine speed sensor 19 of engine 1, primary pulley speed sensor 2 of continuously variable transmission 4
1, a secondary pulley rotation speed sensor 22, and sensors 23, 24 for detecting the operating conditions of air conditioners and chokes. Also,
The shift lever 25 of the operation system is mechanically coupled to the forward / reverse switching device 3 and has a shift position sensor 26 for detecting each range of reverse (R), drive (D), and sporty drive (Ds). Further, the accelerator petal 27 has an accelerator switch 28 for detecting the accelerator depression state,
A throttle opening sensor 29 is provided on the throttle valve side. Various signals of the switches and sensors are input to the electronic control unit 20 and processed by software using a microcomputer or the like. Then, the clutch control signal output from the electronic control unit 20 is input to the electromagnetic clutch 2, and the shift control signal and the line pressure control signal are input to the hydraulic control circuit 17 of the continuously variable transmission 4 to perform each control operation. There is. Referring to FIG. 2, the electromagnetic clutch control system and the continuously variable transmission control system of the control unit 20 will be described. First, the electromagnetic clutch control system has a reverse excitation mode determination section 32 to which signals of the engine speed Ne and the shift position sensor 26 other than R, D, and Ds parking (P) and neutral (N) ranges are input. , For example, if Ne <300 rpm,
Alternatively, in the case of the P and N ranges, the reverse excitation mode is determined, and the output determination unit 33 causes a minute current in the opposite direction to the normal direction to flow. Then, the electromagnetic clutch 2 is completely released except the residual magnetism.
Further, it has an energization mode determination unit 34 to which the determination output signal of the reverse excitation mode determination unit 32, the depression signal of the accelerator switch 28, and the rotation signal (vehicle speed V) of the secondary pulley rotation speed sensor 22 are input, and traveling such as starting. The state is determined, and this determination signal is input to the start mode current setting unit 35, the drag mode current setting unit 36, and the direct connection mode current setting unit 37. The start mode current setting unit 35 sets the start characteristics separately in relation to the engine speed Ne and the like in the case of a normal start or a start using an air conditioner or a choke. Then, the starting characteristic is corrected by each running range of the throttle opening θ and the vehicle speed V, R, D, Ds, and the clutch current is set. The drag mode current setting unit 36 determines a minute drag current when the accelerator is released at a low vehicle speed in each range of R, D, Ds,
A drag torque is generated in the electromagnetic clutch 2 so that the belt and the drive system are squeezed together to smoothly start the vehicle. Further, in this mode, the current is set to zero until just before the vehicle is stopped after the clutch in the D range is released to ensure coasting. The direct-coupling mode current setting unit 37 determines the direct-coupling current according to the relationship between the vehicle speed V and the throttle opening θ in each range of R, D, and Ds, completely engages the electromagnetic clutch 2, and saves power in the engaged state. . The output signals of these current setting units 35, 36, and 37 are input to the output determination unit 33, and the clutch current is determined according to the instruction. Next, regarding the shift speed control system of the continuously variable shift control, the primary pulley speed Np and the secondary pulley speed Ns of the primary pulley speed sensor 21 and the secondary pulley speed sensor 22 are input to the actual speed ratio calculating unit 40. , The actual speed ratio i is calculated from the actual speed ratio i = Np / Ns. This actual gear ratio i and the throttle opening θ of the throttle opening sensor 29
Is input to the target primary pulley rotation speed search unit 41, and R, D,
The target primary pulley rotation speed NPD is searched using the i-θ map based on the shift pattern for each range of Ds.
The searched target primary pulley rotation speed NPD, the engine torque T obtained by the engine torque search unit of the line pressure control system, the ON / OFF signal of the air conditioner switch 23, and the actual gear ratio i are the target primary pulley rotation speed. It is input to the correction unit 49, where it is determined whether or not the output is greater than or equal to the load / load (the load ROAD-LOAD corresponding to the flat road running resistance of the vehicle) based on the engine torque T and the vehicle speed.
If it is equal to or higher than the load, the driving force due to the operation of the air conditioner is supplemented, and if it is equal to or lower than the load / load, the corrected primary pulley rotation speed NDC that does not perform this correction is output, and the secondary pulley rotation speed Ns is output to the target gear ratio calculation unit 42. Input and the target speed ratio is is calculated by is = NPDC / Ns. The target speed ratio is is calculated by the target speed ratio change speed calculation unit 43.
And the target speed ratio change speed dis / dt is calculated from the amount of change in the target speed ratio is for a fixed time. Then, these actual speed ratio i, target speed ratio is, target speed ratio change speed dis / dt,
The coefficients K ₁ and K ₂ of the coefficient setting unit 44 are input to the shift speed calculation unit 45, and the shift speed di / dt is calculated as follows. di / dt = K ₁ (is-i) + K ₂ · dis / dt In the above equation, is-i is a control amount of the target and actual gear ratio deviation, and dis / dt is a delay correction element of the control system. The above-mentioned shift speed di / dt and the actual gear ratio i are such that the duty ratio D is D
= Di / dt, i), the duty ratio D in upshift and downshift is di / dt-i.
It is searched using the map of. The value of the duty ratio D of this operation amount is output to the shift speed control solenoid valve 48 of the hydraulic control circuit 17 via the drive unit 47. Next, a line pressure control system for continuously variable shift control will be described. Engine speed sensor 19, throttle opening sensor 29
The engine torque retrieving unit 50 is used to input the engine speed Ne and the throttle opening θ, and the engine torque T is obtained from the torque characteristic map of θ-Ne. This engine torque T
And the signal of the actual gear ratio i of the actual gear ratio calculation unit 40 is input to the target line pressure setting unit 51, and the target line pressure PLd is determined by the product of the required line pressure corresponding to the engine torque and the actual gear ratio i. On the other hand, since the maximum line pressure value fluctuates as the pump discharge pressure changes depending on the engine speed, the maximum line pressure retrieving unit 52 to which the engine speed Ne and the actual gear ratio i are input to detect this fluctuation state. And the maximum line pressure PLmax is obtained from the Ne-i map. The target line pressure PLd and the maximum line PLmax are input to the reduced pressure value calculation unit 53, and the line pressure PLR is set at the ratio of the target line pressure PLd to the maximum line pressure PLmax.
Which is input to the duty ratio search unit 54 to determine the duty ratio D according to the line pressure PLR.
The duty signal is output to the line pressure control solenoid valve 56 via the drive unit 55. Next, the operation of the shift control device for the continuously variable transmission configured as described above will be described. First, the power corresponding to the depression of the accelerator from the engine 1 is input to the primary pulley 14 of the continuously variable transmission 4 via the electromagnetic clutch 2 and the forward / reverse switching device 3, and the drive belt 16,
The power that has been changed by the secondary pulley 15 is output, and the power is transmitted to the drive wheels 9 to drive the vehicle. While the vehicle is traveling, the target line pressure is set larger as the engine torque T is larger in the low speed stage where the value of the actual gear ratio i is large, and a duty signal corresponding to this is input to the solenoid valve 56 to regulate the control pressure. The line pressure PL is increased by controlling the line pressure with the averaged pressure. The actual speed ratio i
Becomes smaller and the engine torque T also becomes smaller, so that the line pressure PL is controlled so as to decrease. Thus, the pulley pressing force corresponding to the transmission torque of the drive belt 16 is always applied. . The line pressure PL is constantly supplied to the secondary cylinder 15a, and the shift speed is controlled by supplying and discharging oil to the primary cylinder 14a by a shift speed control valve (not shown) controlled by the control pressure of the solenoid valve 48. Will be described below. First, the signals Np, Ns, and θ from the primary pulley rotation speed sensor 21, the secondary pulley rotation speed sensor 22, and the throttle opening sensor 29 are read, and the actual gear ratio calculation unit 40 of the control unit 20 obtains the actual gear ratio i. . Further, in the target primary pulley rotation speed search section 41, R from the shift position sensor 26,
Based on the shift pattern for each range of D and Ds, the actual gear ratio
The target primary pulley rotation speed NPD is once retrieved from the map based on i and the throttle opening θ, and is input to the target primary pulley rotation speed correction unit 49. Here, the load-equivalent torque TRL as illustrated in FIG. 3 is obtained from the vehicle speed and the engine torque T from the engine torque retrieval unit 50, and the target primary pulley rotation speed is executed by the execution procedure shown in the flowchart of FIG. Correct NPD. That is, in step S1 and step S2 of FIG. 4, the engine torque T and the load / load equivalent torque TRL are searched, and it is determined in step S3 whether or not the air conditioner is operating. If not, step S6 And the target primary pulley rotation speed NPD is not corrected. If the air conditioner is operating in step S3, the process proceeds to step S4, engine torque T ≧ load / load equivalent torque TRL is determined, and if engine torque T <load / load equivalent torque TRL, proceed to step S6. The target primary pulley rotation speed NPD is not corrected after the transition, and T ≧
If it is TRL, the process proceeds to step S5, and the corrected primary pulley rotation speed NPDC for correcting to the primary pulley rotation speed down-shifted so as to correct the torque equivalent to the load increase due to the air conditioner operation is output. The corrected primary pulley rotation speed NPDC and the secondary pulley rotation speed Ns obtained by the above procedure are input to the target gear ratio calculation unit 42, and the target gear ratio is corresponding to the corrected primary pulley rotation speed NPDC is calculated. Therefore, in the region where the primary pulley rotation speed is constant, the target gear ratio is has the same fixed value as that calculated by the Ns-θ method, but in the region where the primary pulley rotation speed is variable, the target gear ratio is is Ns. −
Compared with the one calculated by the θ method, when the engine torque T ≧ load / load equivalent torque TRL when the air conditioner is operating, etc., it is set by offsetting to the low speed side, but when the air conditioner is not operating or the engine torque T < At the time of load-torque equivalent torque TRL, the target gear ratio is is obtained in which the offset value is suppressed. Using the actual speed ratio i, the target speed ratio is, the dis / dt of the target speed ratio change speed calculation unit 43, and the coefficients K ₁ and K ₂ of the coefficient setting unit 44, the speed change ratio calculation unit 45 calculates the speed change speed di / dt. Ask for. Then, the duty ratio search unit 46 searches for the duty ratio D based on the shift speed di / dt and the actual shift ratio i. The duty signal is input to the solenoid valve 48 to generate a pulsed control pressure, which causes the shift speed control valve to repeatedly operate at two positions, oil supply and oil discharge. If the duty ratio becomes smaller, the shift speed control valve will operate longer at the lubrication position due to the off time, and the primary cylinder
It came to refuel 14a and thus upshifted. On the other hand, when the duty ratio becomes large, conversely, the operating time at the oil drain position becomes longer due to the on time, and the primary cylinder 14a is drained of oil, which causes a downshift.
Since the shift speed di / dt in this case corresponds to the change of the duty ratio, when the deviation between the target gear ratio is and the actual gear ratio i is small, the change of the duty ratio is small and the flow rate change of the primary cylinder 14a is small. The shift speed becomes slower because there is less. On the other hand, as the deviation between the target gear ratio is and the actual gear ratio i increases, the change in the duty ratio increases the change in the flow rate of the primary cylinder 14a, resulting in a faster gear change speed. In this way, in the entire shift range between the low speed stage and the high speed stage, the shift speed is changed while upshifting or downshifting to continuously shift. The operation of the present invention has been described above. In the process of calculating the target gear ratio is based on the target primary pulley rotation speed NPD and the secondary pulley rotation speed Ns, the target primary pulley rotation speed NPD is set to the target primary pulley rotation speed. In the correction unit 49, only when the engine torque T is in a traveling state larger than the load-torque equivalent torque TRL,
Since the target primary pulley rotation speed NPD corresponding to the increase in engine load due to the air conditioner is corrected and downshifted, it is unnecessary for the air conditioner when the engine torque T is low compared to the load-torque equivalent torque TRL. Avoid a reduction in driving force and engine braking. In the above embodiment, an example of load increase due to operation of the air conditioner has been described, but the same effect as that of the above embodiment can be obtained when applied to load increase other than operation of the air conditioner.

【The invention's effect】

As described above, according to the present invention, in the shift control using the target value, it is possible to prevent the deterioration of drivability caused by the operation of the air conditioner when the engine torque is lower than the load torque. .

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of an embodiment of a shift control device according to the present invention, FIG. 2 is a block diagram showing a configuration of a control system, and FIG. 3 is a search for a load / load equivalent torque TRL and an engine torque search unit. FIG. 4 is a diagram illustrating the relationship with the engine torque T, and FIG. 4 is a flowchart for explaining the execution procedure in the target primary pulley rotation speed search unit and the target primary pulley rotation speed correction unit. 22 …… Secondary pulley rotation speed sensor, 41 …… Target primary pulley rotation speed search unit, 42 …… Target gear ratio calculation unit,
49 …… Target primary pulley speed correction unit.

Claims (1)

(57) [Claims] 1. A process of calculating a target gear ratio based on a target primary pulley rotation speed and a secondary pulley rotation speed in a gear shift control system in which an operation amount is determined and controlled by elements of a target value and an actual value based on the gear ratio. Is provided with means for correcting the target primary pulley rotation speed, and the correction means limits the target primary pulley rotation speed only when the engine torque is larger than the load torque to increase the load caused by air conditioner operation or the like. A shift control device for a continuously variable transmission, characterized by performing corresponding correction.