JPH01197135A - Control device for continuously variable transmission - Google Patents

Abstract

PURPOSE:To aim at enhancing the startability of a vehicle by setting the control line pressure for a continuously variable transmission to a minimum value while releasing a clutch when a start of an engine is detected in such a condition that the rotational speed of the engine and the time are below set value. CONSTITUTION:An engine 1 is coupled to a continuously variable transmission 4 through the intermediary of a clutch 2 and a forward and backward change- over device 3. Further, the continuously variable transmission 4 is coupled to drive wheels 9 through transmission means 5 through 7 and an axle 8. Further, an electronic control unit 20 receives detection signals from various switches and sensors 19, 21-29 for detecting the operating condition of the engine. Meanwhile, the electronic control unit 20 delivers various control signals to the clutch 2 and a hydraulic control circuit 17 for the continuously variable transmission 4. In this arrangement, when a start of the engine is determined in such a condition that the engine rotational speed and the time are below set values, the line pressure of the hydraulic control circuit 17 is set to a minimum value while the clutch 2 is released.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a control device for a belt-type continuously variable transmission for a vehicle, and more particularly to line pressure and clutch control during engine starting.

[Conventional technology]

Generally, in a continuously variable transmission, line pressure is generated in the hydraulic control system,
This line pressure is used to supply and drain oil to the cylinders of each primary and secondary boob to achieve continuously variable speed. Here, in order to keep the line pressure at the minimum necessary level, it is variably controlled by input torque, gear ratio, etc. By the way, when the engine is started, the gear ratio of the continuously variable gear ratio is at its maximum, and in response to this gear ratio, various constants of the electric control system are reset, resulting in a high line pressure. Therefore, the load on the oil pump is large when starting the engine, and the load on the starter increases accordingly, requiring a large-capacity stator, battery, and alternator, which is undesirable in terms of fuel efficiency, cost, weight, etc. Therefore, it is desirable to temporarily reduce the starter load when starting the engine. Also, when combined with an automatic clutch such as an electromagnetic clutch, move the select lever to reverse (R) immediately after starting the engine.
Alternatively, when shifting to drive (D), the clutch is automatically engaged by accelerator operation or the like to transmit power. At this time, if the line pressure of the continuously variable transmission is not at a predetermined oil pressure, there is a risk of belt slipping or the like. Therefore,
When starting by engaging the clutch, it is necessary to take into consideration the state of the line pressure in the continuously variable transmission. Conventionally, there is a prior art technique for line pressure control of a continuously variable transmission, for example, as disclosed in Japanese Patent Application Laid-Open No. 60-49158. Here, it is shown that the line pressure is controlled based on the relationship between input torque and gear ratio.

Problem to be Solved by the Invention J By the way, the above-mentioned prior art is about line pressure control after sufficient line pressure has been generated. Therefore, it does not deal with an increase in starter load when starting the engine. In view of these points, the present invention has been developed to reduce the starter load when starting the engine, and to further control the starting of the automatic clutch by switching to the starting range immediately after starting so as not to cause belt slip. An object of the present invention is to provide a control device for a step-change transmission. [Means for Solving the Problems] In order to achieve the above object, the present invention provides a control system for a continuously variable transmission equipped with a clutch that is automatically started. If the engine start determination unit determines that the engine speed and time are below the set values and the engine start is determined to be started, the line pressure control system controls the line pressure to the lowest level and simultaneously disengages the clutch. Configured to remain free.

[For production]

Based on the above configuration, when starting the engine, the line pressure is temporarily set to the lowest value by the engine start determination section, and at the same time, the clutch remains released even when the accelerator is operated to prevent the engine from starting, and then the line pressure is controlled. The vehicle will be able to launch once it returns to normal. In this manner, in the present invention, the starter load is lightened by controlling the line pressure to the minimum level when starting the engine, and it is possible to prevent belt slip and the like due to insufficient start preparation.

【Example】

Embodiments of the present invention will be described below based on the drawings. Referring to FIG. 1, the entire configuration of a drive system that combines an electromagnetic clutch and a belt-type continuously variable transmission will be described. The engine 1 is connected to a continuously variable transmission fi4 via an electromagnetic clutch 22, such as a 44 magnetic particle type, and a forward/reverse switching device 3. Output shaft 6. The transmission is configured to be transmitted to drive wheels 9 via a differential gear 7 and an axle 8. 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 with a clutch coil 2C. Then, due to the clutch current flowing through the clutch coil 2C, both members 2a,
Electromagnetic powder is bonded and accumulated in the gap between 2b in a cast shape, and the resulting bonding force variably controls clutch engagement/disengagement and clutch torque. The forward/reverse switching device 3 is configured in a synchronous meshing manner between an input shaft 11 and a transmission main shaft 12 by gears, a hub, or a sleeve, and has at least a forward position where the input shaft 11 is directly connected to the main shaft 12, and a forward position where the input shaft 11 is directly connected to the main shaft 12. 11 is reversed and transmitted to the main shaft 12. The continuously variable transmission n4 has a main shaft 12 and a subshaft 13 disposed parallel to the main shaft 12, and the main shaft 12 is provided with a hydraulic cylinder 14a.
Similarly, a secondary pulley 15 with a hydraulic cylinder 15a'll is provided. Further, a drive belt 16 is wound around both pulleys 14 and 15, and both cylinders 14a,
15a is configured as a hydraulic control circuit 17. 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 causes the drive belt 16 to wrap around the pulley 14.15 steplessly by changing the diameter ratio. It is configured to perform speed change control. Next, the electronic control system of the electromagnetic powder clutch 2 and the continuously variable transmission 4 will be explained. Engine speed sensor 19 for engine 1. Stepless change 31! Primary pulley rotation speed sensor 21 of machine 4. Secondary pulley rotation speed sensor 22. It has sensors 23 and 24 that detect the operating status of the air conditioner and choke. The operating shift lever 25 is mechanically connected to the forward/reverse switching device 3, and has a shift position sensor 26 that detects each range of reverse (R), drive (D), and sporty drive (DS). have Further, the accelerator pedal 27 has an accelerator switch 28 for detecting the accelerator depression state, and a throttle opening sensor 29 for opening the throttle valve. The various signals from 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 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 continuously variable speed control system of the control unit 20 will be explained. First, the electromagnetic clutch control system includes a reverse excitation mode determination section 32 to which the engine speed Ne and signals of parking (P) and neutral (N) ranges other than R, D, and DS of the shift position sensor 26 are input. , for example Ne <3
In the case of 00rpn or in the P or N range, it is determined that the reverse excitation mode is selected, and the output determination unit 33 causes a small current in the opposite direction to the normal flow to flow, and then the residual magnetism of the magnetic clutch 2 is removed and the magnetic clutch 2 is completely released. . In addition, the determination output signal of the reverse excitation mode determination section 32, the depression signal of the accelerator switch 28, and the rotation (
The energization mode determination section 34 receives a signal (hereinafter referred to as 3 mV), and determines the running state such as starting, and this determination signal is input to the starting mode current setting section 35. Drag mode current setting section 36. The current is input to the direct connection mode current setting section 37. The starting mode current setting unit 35 separately sets starting characteristics in relation to the engine rotation speed Ne, etc. in the case of normal starting or starting using an air conditioner or a choke. Then, throttle opening θ, vehicle speed ■. The clutch current is set by correcting the starting characteristics according to each driving range of R, D, and Ds. The drag mode current setting unit 36 determines a slight drag current when the accelerator is released at low vehicle speed in each of the R, D, and DS ranges, and generates drag torque in the electromagnetic clutch 2 to reduce play in the belt and drive system. In Manako mode, which allows smooth start, the current is set to zero until just before the vehicle stops after the clutch is released in the D range, ensuring coasting performance. The direct-coupling mode current setting unit 37 determines the direct-coupling current based on the relationship between the vehicle speed V and the throttle opening θ in each range of R, D, and Ds, fully 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 determining unit 33, and the clutch current is determined according to the instructions thereof. Next, to describe the speed change control system of continuously variable speed control, the primary rotation speed Nρ and the secondary rotation speed NS of the primary pulley rotation speed sensor 21° and the secondary pulley rotation speed sensor 22 are input to the actual speed ratio calculation unit 40, Actual speed ratio i is calculated from actual speed ratio i=Np/Ns. This actual gear ratio i and the throttle opening θ of the throttle opening sensor 29 are input to the target primary rotation speed search unit 41, and R
, D, and DS based on the shift pattern for each range.
The target primary rotation speed NPD is searched using the map. The target primary rotation speed NPD and the secondary rotation speed NS are input to the target gear ratio calculation unit 42, and the target gear ratio is
= N PD / N s. This target gear ratio is is then input to the target gear ratio change rate calculating section 43, and a target gear ratio change rate dis/dt is calculated based on the amount of change in the target gear ratio is over a certain period of time. These actual gear ratio i, target gear ratio iS, and target gear ratio change speed d i
s/dt and the coefficients 1 and 2 of the coefficient setting section 44 are input to the shift speed calculation section 45, and the change "s3! degree di/dt
is calculated as follows. di/dt = 1 (is-i) + 2 ・
dis/dt In the above equation, 1s-i is the control amount between the target and actual gear ratio, and dis/dt is the delay correction element of the control system. The shift speed di/dt and the actual shift ratio i are input to the duty ratio search section 46. Here, since the duty ratio of the manipulated variable is set according to the relationship D = f (di/dt, i), the duty ratio is set using a map with di/dt-i for upshifts and downshifts. Searched. The value of the duty ratio of this operation amount is outputted to the shift speed control solenoid valve 48 of the hydraulic control circuit 17 via the drive unit 47. Next, the line pressure control system for continuously variable transmission control will be described. Engine speed sensor 19. Throttle opening sensor 2
The engine torque retrieval unit 50 receives the engine rotational speed Ne of 9 and the throttle opening θ, and calculates the engine torque T from the torque characteristic map of θ-Ne. The engine torque T and the signal of the actual gear ratio i from the actual gear ratio calculation unit 40 are as follows:
The target line pressure PL is input to the target line pressure setting unit 51 and is determined by the product of the required line pressure according to the engine torque and the actual gear ratio i.
Define d. On the other hand, as the bong discharge pressure changes depending on the engine speed, the maximum line pressure value also changes, so in order to detect this fluctuation state, the maximum line pressure search section inputs the engine speed No. and the actual gear ratio i. 52,
The maximum line pressure P Llax is determined from the map of Ne-1. Target line pressure PLd and maximum line pressure P LlaX
is input to the pressure reduction value calculation unit 53, and the maximum line pressure P Lia
Line pressure PLR is the ratio of target line pressure PLd to x.
This is input to the duty ratio search section 54 to determine the duty ratio corresponding to the line pressure PLR. The duty signal is configured to be outputted to the line pressure control solenoid valve 56 via the drive section 55. Therefore, in the above control system, the ignition switch 60 is used to control the line pressure and clutch when starting the engine.
signal and the engine speed N of the engine speed sensor 19
e is input to the starting rotation speed detection section 61. It has a timer 62 that is set by an on signal from an ignition switch 60, and these signals are input to an engine start determination section 63. The engine start determination section 63 determines whether to start the engine until the engine rotation speed Ne detected by the starting rotation speed detection section 61 becomes equal to or greater than the set value N, and the time t after starting determined by the timer 62 becomes equal to or greater than the set value to. The signal from the engine start determination section 63 is inputted to the drive section 55 via the line pressure minimum setting section 64 in the line pressure control system to maintain the duty ratio at 0%. Further, a clutch current supply determining section 65 is added to the output determining section 33 of the electromagnetic clutch control system, and when the engine starting determining section 63 determines that the engine has started, the clutch current is 3! ! Outputs the error. Next, the operation of the control device configured in this way is explained in the third section.
This will be explained using the flowchart shown in the figure. First, when turning on the ignition switch 60 to turn the starter when starting the engine, the starting rotation speed detection section 61
Then, the engine speed Ne and its set value No are Ne <N
Since the time t and the set value to of the timer 62 are t<to, the engine start determination unit 63 determines to start the engine. As a result, the duty ratio of the line pressure control system is forcibly set to 0% by the line pressure minimum setting section 64, so that the starter is driven with the line pressure at its minimum. On the other hand, as a result of the engine start determination at this time, a cutoff signal is output from the clutch current supply determining section 65 to the output determining section 33, so that the clutch 2 is forcibly kept in the released state regardless of the select range position of the select lever. Then, the engine speed Ne and its set value NO are Ne≧
When NC1+time t and its time value to become t≧to and the engine starts up, the engine start determination unit 63
The engine start determination is canceled, and therefore, the line pressure control system outputs a duty ratio signal according to the duty ratio search section 54 via the drive section 55, so that the line pressure is normally controlled. On the other hand, in the clutch control system, the clutch current supply determination unit 6
5, the output of the clutch current supply is input to the output determination section 33, and the clutch current can be supplied. Therefore, when the select range is switched to a position other than P or N and the accelerator is depressed, the electromagnetic clutch 2 is automatically engaged, and the power from the engine 1 is transferred to the primary pulley of the continuously variable transmission 4 via the forward/reverse switching device 3. 14, drive belt 1
6. The power shifted by the secondary pulley 15 is output, and this is the driving force 9jJ wheel 91'Jl! It runs by transmitting the signal to 1. During the above-mentioned driving, the target line pressure is set to be larger as the engine torque T is larger in the lower speed gear where the value of the actual gear ratio i is larger, and a duty signal corresponding to this is input to the solenoid valve 56 to generate the control pressure. By controlling the line pressure using the averaged pressure, the line pressure PL is increased. Then, as the shift to a high speed gear occurs, the gear ratio 1 becomes smaller and the engine torque T also becomes smaller, so that the line pressure P is controlled to decrease. Pushing the pulley exerts a force corresponding to the transmitted torque of . The line pressure pt is always supplied to the secondary cylinder 15a, and is supplied to the primary cylinder 14a by a speed change control valve (not shown) using the control pressure of the solenoid valve 48.
By supplying and draining oil to and from the engine, the shifting speed is controlled. Although one embodiment of the present invention has been described above, it is also applicable to automatic clutches other than electromagnetic clutches. [Effects of the Invention] As described above, according to the present invention, when starting the engine in a vehicle equipped with a continuously variable transmission, the line pressure is temporarily controlled to the lowest level to reduce the oil pump load. The load on the engine becomes lighter, the starter, battery, etc. become smaller, and starting performance improves. Since the clutch is kept in a released state when the engine is started, belt slip can be prevented when torque is transmitted in a state where line pressure is insufficient even when the engine suddenly starts (D or R) immediately after starting.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing an embodiment of a control device for a continuously variable transmission according to the present invention, FIG. 2 is a block diagram of a control system, and FIG. 3 is a flowchart of the operation. 2... Electromagnetic clutch, 4... Continuously variable transmission, 20...
・Electronic control unit, 63...engine start determination section,
64...Line pressure minimum setting section, 65...Clutch current supply judgment section Patent applicant: Fuji Heavy Industries Co., Ltd. Agent Patent attorney: F# Nobuaki Susumu Patent attorney: Susumu Murai

Claims (1)

[Scope of Claims] A control system for a continuously variable transmission equipped with a clutch subjected to automatic start control, comprising an engine start determination section that makes a determination based on the engine rotation speed and time at the time of engine start, the engine start determination section The continuously variable transmission is characterized in that when it is determined to start the engine when the engine speed and time are below a set value, the line pressure control system controls the line pressure to the minimum and simultaneously keeps the clutch in a released state. Control device.