JPH0657509B2 - Controller for continuously variable transmission - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a belt type continuously variable transmission for a vehicle, and more particularly, to prevention of rearward displacement when starting on a slope. Regarding the shift control of this type of continuously variable transmission, for example, there is a basic hydraulic control system disclosed in Japanese Patent Laid-Open No. 55-65755. This is to set the gear ratio so that the gear ratio control valve is balanced by the factors of the accelerator depression amount and the engine speed, and the engine speed is always uniquely determined. I have to. Therefore, the shift speed is mechanically determined by each gear ratio, line pressure, control valve, etc., and the shift speed cannot be directly controlled. Therefore, it has been pointed out that the gear ratio causes hunting, overshoot, and the like to deteriorate drivability in the transient state of the driving range. For this reason, in recent years, there has been a tendency to electronically control the transmission of a continuously variable transmission in consideration of the transmission speed. Further, along with the electronic control of the shift control by the shift speed, the line pressure tends to be electronically controlled. Here, in a vehicle equipped with a continuously variable transmission, it is important to improve the performance of gear shift control to improve fuel efficiency and drivability as described above. It is desirable to consider the operability and operability.

[Prior art]

Therefore, conventionally, as a hill holder mechanism of a vehicle, for example, there is a prior art disclosed in Japanese Utility Model Laid-Open No. 60-43461. Here, it is shown that the operating lever of the hydraulic pressure holding valve provided in the cross pipe of the brake system of the vehicle is operated by the suction pipe negative pressure of the engine to brake when the vehicle is stopped on a slope or the like.

[Problems to be Solved by the Invention]

By the way, in the above-mentioned conventional one, since it is a method of temporarily holding the braking force automatically, it is necessary to release the braking force without malfunctioning due to empty skid etc. at the start,
The timing of this release is also difficult. Therefore, it is preferable to use drag by an engine such as a vehicle with an automatic transmission. Here, an automatic clutch such as an electromagnetic clutch can cause dragging by applying a drag torque when the accelerator is released to stop the vehicle. Further, in the continuously variable transmission, the bandone type belt mainly produces a frictional force due to a canceling slip between the ring and the element, which reduces the transmission torque. The frictional force is proportional to the ring tension, that is, the magnitude of the line pressure acting on the pulley. Therefore, at the time of ordinary traveling, it is preferable to reduce the line pressure to the minimum necessary level capable of transmitting the engine output, because this leads to an improvement in transmission efficiency. On the other hand, when the line pressure is increased to increase the frictional force, the smooth rotation of the belt is hindered by the frictional force, and the stopping function is exerted. Therefore, if the stopping function of the vehicle due to the line pressure and the dragging due to the drag torque of the automatic clutch are combined, the hill holder function on a slope can be exhibited. The present invention has been made in view of such a point, and in the one with an automatic clutch, the clutch torque is used, and the belt friction force due to the line pressure is reversely used to effectively operate the hill holder. It is an object of the present invention to provide a control device for such a continuously variable transmission.

[Means for solving problems]

In order to achieve the above object, a control device for a continuously variable transmission according to the present invention includes a primary pulley and a secondary pulley each having a variable pulley interval on a main shaft on an engine side and a sub shaft on a wheel side arranged in parallel with the main shaft. And a drive belt wound between both pulleys, the primary pulley and the secondary pulley are provided with hydraulic cylinders, and the effective diameter of the pulleys is changed by the line pressure supplied to the hydraulic cylinders so that the pulleys between the main and auxiliary shafts can be changed. The continuously variable transmission, which comprises a continuously variable transmission for continuously controlling the ratio of the ratio and an automatic clutch provided between the engine and the continuously variable transmission, is detected by a detection signal of detection means for detecting various running conditions. And a control device for a continuously variable transmission including control means for controlling the automatic clutch, the detection device for detecting a traveling condition for stopping the vehicle at a secondary pulley rotation speed. Means for providing a predetermined drag torque to the automatic clutch based on the signal from the shift position sensor, the secondary pulley rotation speed, and the signal from the accelerator switch. A hillholder determining means for determining the setting of the hillholder action from the application of the drag torque is provided, and a line pressure control means for setting the line pressure of the continuously variable transmission higher than that in the normal operating state by the output of the hillholder determining section is provided. It is characterized by that.

[Action]

Based on the above configuration, when the vehicle is stopped on a slope, the hill holder function is generated by the synergistic effect of dragging by the drag torque of the automatic clutch and the stop function by the belt of the continuously variable transmission. The hill holder function will be automatically released as soon as the vehicle is connected and the line pressure becomes normal. Thus, according to the present invention, it is possible to use the characteristics of the automatic clutch and the continuously variable transmission, and to operate the hill holder without adding a special device.

【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 and a forward / reverse switching device 3, and is connected to the continuously variable transmission 4 via a set of reduction gears 5, an output shaft 6, a differential gear 7 and an axle 8. Is configured to be transmitted to the drive shaft 9. The electromagnetic clutch 2 has a drive member 2a on the engine crankshaft 10 and a driven member 2b having a clutch coil 2c on the input shaft 11. Then, by the clutch current flowing through the clutch coil 2c, electromagnetic powder is coupled and accumulated in a chain between the members 2a and 2b in a chain shape, and the coupling force thereby variably controls the clutch engagement / disengagement and the clutch torque. 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 a sub shaft 13 arranged in parallel therewith.
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 transmission torque is supplied to both cylinders 14a and 15a to apply a pulley pressing force, and the ratio of the winding diameter of the drive belt 16 to the pulleys 14 and 15 is changed by the primary pressure to continuously change the speed. Is configured to control. Next, an electronic control system for the electromagnetic clutch 2 and the continuously variable transmission 4 will be described. Engine speed sensor 1 of engine 1
9. It has rotation speed sensors 21, 22 for the primary pulley and secondary pulley of the continuously variable transmission 4, and sensors 23, 24 for detecting the operating conditions of air conditioners and chokes. Further, the shift lever 25 of the operation system is mechanically coupled to the forward / reverse switching device 3, and a shift position sensor for detecting each range of reverse (R), drive (D), and sporty drive (Ds).
Has 26. Further, the accelerator pedal 27 has an accelerator switch 28 for detecting the accelerator pedal depression state, and a throttle opening sensor 29 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. The electromagnetic 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. ing. In FIG. 2, the electromagnetic clutch and the line pressure control system of the control unit 20 will be mainly described. First, the primary pulley rotation speed N of the sensors 21, 22, 29
Each signal of p, the secondary pulley rotation speed Ns, and the throttle opening θ is input to the shift control unit 30, and the shift speed di / dt
The control signal according to is output. Next, the line pressure control system will be described. In the line pressure control unit 31, the signal θ of the throttle opening sensor 29 and the signal Ne of the engine speed sensor 19 are input to the engine torque calculation unit 40, and a table of θ-Ne is obtained. The engine torque T is calculated from On the other hand, the required line pressure setting unit 41 calculates the required line pressure P _Lu per unit torque based on the actual gear ratio i from the shift control unit 30, and this and the engine torque T of the engine torque calculation unit 40 are the target line. It is input to the pressure calculation unit 42 and the target line pressure P _L is calculated by P _L = P _Lu · T. The output P _L of the target line pressure calculation unit 42 is input to the duty ratio setting unit 43 to determine the duty ratio D corresponding to the target line pressure P _L , so that the line pressure control signal of the duty ratio D is output. It has become. In the electromagnetic clutch control system, the electromagnetic clutch control unit 38
Engine speed Ne and R of the shift position sensor 26,
It has a reverse excitation mode determination unit 32 to which a signal of the traveling range of D and Ds is input. For example, in the case of Ne <300 rpm, or in the parking (P) or neutral (N) range, the reverse excitation mode is determined and output. The determination unit 33 passes a minute current in the opposite direction to the normal one. Then, the electromagnetic clutch 2 is completely released except the residual magnetism. Also, this reverse excitation mode determination unit
A determination output signal of 32, a depression signal of the accelerator switch 28, and a vehicle speed V signal of the secondary pulley rotation speed sensor 22 are included in an energization mode determination unit 34, which determines a running state such as starting. Input to each current setting section 35, 36, 37 in mode, drag mode and direct connection mode. The start mode current setting unit 35 is used for normal start or air conditioning,
Engine speed N when starting with a choke
The starting characteristics are set separately in relation to e, etc. Then, the starting characteristics are corrected according to the travel ranges of the throttle opening θ and the vehicle speeds V, R, D, Ds, and the clutch current is set. The drag mode current setting unit 36 determines a slight drag current when the accelerator is released at a low vehicle speed in each of the R, D, and Ds ranges, and generates a drag torque in the electromagnetic clutch 2 to reduce backlash of the belt and drive system. , Take off smoothly. 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 of the R, D, and Ds ranges, completely engages the electromagnetic clutch 2, and saves power in the engaged state. . The output signals of these current setting sections 35, 36 and 37 are input to the output determination section 33 and the clutch current is determined according to the instruction, and the map of each mode is as shown in FIG. In the above control system, the hill holder means will be described. The hill holder means has a vehicle stop detection unit 45 for inputting the secondary pulley rotation speed Ns according to the vehicle speed, and the secondary pulley rotation speed Ns =
The stop is detected by O. The drag torque of the electromagnetic clutch 2 is detected from the output of the output determination unit 33 or the drag mode current setting unit 36, and the drag torque signal and the vehicle stop signal are input to the hill holder determination unit 46, and the duty of the line pressure control system is determined. A correction unit 47 added to the output side of the ratio setting unit 43 corrects the line pressure higher than that in normal operation. Next, the operation of the control device thus configured will be described. First, the electromagnetic clutch 2 determines which mode it is in based on various input signals, and automatically disengages by applying a clutch current according to each mode. When the engine output is transmitted to the continuously variable transmission 4 by the electromagnetic clutch 2, the continuously variable transmission 4 also controls the line pressure and the gear shift by various input signals, so that the continuously variable power is output and the vehicle travels. To do. Here, when the vehicle speed becomes equal to or lower than the set vehicle speed when the accelerator is released in the traveling range, the drag mode is selected in the electromagnetic clutch 2, and the drag torque Td is generated as shown in FIG. This drag torque Td is set as large as possible within the range in which the vehicle does not creep. When the vehicle stops, it is detected by the vehicle stop detection unit 45, and the hill holder determination unit
A correction signal is output from 46, and the correction unit 47 sets the line pressure higher than the line pressure control range in the normal operating state as indicated by the diagonal lines in FIG. Therefore, even when the vehicle is stopped on a slope, dragging due to the drag torque Td of the electromagnetic clutch 2 and the belt stopping function due to the high line pressure act together to act as a hill holder. When the accelerator is stepped on as shown in FIG. 4 when the vehicle starts on a slope, the electromagnetic clutch 2 selects the start mode, the clutch torque rises from the drag torque Td, and power is transmitted. The line pressure is set according to the output and the vehicle starts. And with this launch,
The hill holder action is automatically released. Although one embodiment of the present invention has been described above, it may be applied only to an uphill having a predetermined angle or more in the signal of the tilt sensor. Fine control such as synchronizing the decrease of the line pressure with respect to the rise of the clutch torque at the time of starting may be further added. It can also be applied to automatic clutches other than electromagnetic clutches.

【The invention's effect】

As described above, according to the present invention, the characteristics of the automatic clutch and the continuously variable transmission are used to act as the hill holder, so that no special device is required. Further, the action of the hill holder can be easily released, and the release timing can be easily set when the vehicle starts on a slope.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a control device of the present invention, FIG. 2 is a block diagram of a control unit, FIG. 3 is a diagram showing maps of respective modes, and FIG. 4 is a state of hill holder action. It is a characteristic view to show. 2 ... Electromagnetic clutch, 4 ... Continuously variable transmission, 20 ... Electronic control unit, 31 ... Line pressure control unit, 38 ... Electromagnetic clutch control unit, 45 ... Stop detection unit, 46 ... Hill holder determination unit .

Claims (1)

[Claims] 1. A primary pulley and a secondary pulley having variable pulley intervals, and a drive belt wound between the pulleys are respectively provided on a main shaft on an engine side and a sub shaft on a wheel side arranged parallel to the main shaft. A primary pulley and a secondary pulley each having a hydraulic cylinder, and a continuously variable transmission that continuously changes the pulley ratio between the main and auxiliary shafts by changing the effective diameter of the pulley by the line pressure supplied to the hydraulic cylinder; The automatic clutch provided between the engine and the continuously variable transmission, by the detection signal of the detection means for detecting various running conditions,
In a control device for a continuously variable transmission including a control means for controlling the continuously variable transmission and the automatic clutch, a detection means for detecting a traveling condition for stopping the vehicle at a secondary pulley rotation speed is provided, and a signal from a shift position sensor is provided. By the secondary pulley rotation speed and the signal of the accelerator switch,
The automatic clutch control means for applying a predetermined drag torque to the automatic clutch is provided, and the hill holder determination means for determining the setting of the hill holder action from the running condition of the vehicle stop and the application of the drag torque in the automatic clutch is provided, and the hill holder determination part is provided. The control device for a continuously variable transmission, further comprising: line pressure control means for setting the line pressure of the continuously variable transmission higher than that in a normal operating state.