JPS624644A - Control device of continuously variable speed change gear - Google Patents

Abstract

PURPOSE:To satisfy response and maneuverability at the same time, and more over, improve the maneuverability in transient to the engine brake, by setting an object speed change rate, and controlling the speed change rate directly making it as a control object. CONSTITUTION:Signals from sensors 41, 42, and 44 are read, the real speed change ratio (i), the object speed change ratio (is), and then, di/dt are determined in computers and detectors in a control unit 40, finally the duty ratio D being found therefrom. Depending on the amount of the resultant value and the amount of the conversion, a speed change control valve is activated through a solenoid valve 28, the input and output of the control oil and the rate of the flow conversion from the secondary cylinder to the primary cylinder are controlled, and the gear shift and the speed change rate are converted. Moreover, in an engine braking condition, the speed change rate is corrected smaller by the signal from an engine brake detector 53, the speed change rate of shift up is got slower, and the maneuvering property is improved avoiding an acceleration or an anxious feeling.

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 a control device for controlling a speed change of a gear ratio by controlling υJ, and relates to correction when transitioning to an engine braking state.

[Blue eyes of invention]

Regarding the speed change control of this type of continuously variable transmission, there is a basic hydraulic control system disclosed in, for example, Japanese Patent Laid-Open No. 55-65755. In this system, the gear ratio control valve operates in a balanced manner depending on the amount of accelerator depression and engine speed, and determines the gear ratio so that the engine speed is always constant. ing. Therefore, the shifting speed is mechanically determined by each gear ratio, primary pressure, etc., and the shifting speed cannot be directly controlled. For this reason, it has been pointed out that in a transient state of the driving range, the speed change ratio causes hunting, overshoot, etc., which deteriorates drivability. For this reason, in recent years, when controlling the speed of a continuously variable transmission, there has been a tendency to perform electronic control in consideration of the change speed of the gear ratio using J5.

[Prior art l] Conventionally, the continuously variable transmission described above is controlled by considering the speed change speed, for example, in Japanese Patent Application Laid-Open No. 59-159.
There is a prior art of Publication No. 456. This has a gear ratio changing directional switching valve device and a gear ratio changing speed control valve device for speed change control, and when the changing direction switching valve device is switched to either oil supply or oil drain, the changing speed control valve device uses an electromagnetic The valve operates the spool valve at a specified duty ratio to control the speed of change of the gear ratio. Regarding setting the gear change speed, for example, there is Japanese Patent Application Laid-Open No. 59-217048, which describes a feedback system that controls the gear change based on the deviation of the actual speed ratio e from the target speed ratio e'. It is configured to increase or decrease by Δe. [Problems to be solved by the invention] By the way, I';l''! According to the former prior art, 2) T! Since similar valve devices are used, the structure is inevitably complicated. Furthermore, according to the prior art, since the method is to increase or decrease a predetermined amount of change Δe, if the amount of change Δe is set to a large value, the response is good but overshoot etc. will occur, and conversely, the amount of change Δe may be reduced. If it is set, the responsiveness will deteriorate and it will be difficult to set the change amount Δe. In addition, the uniform judgment base W changes 3! in all operating conditions.
``Determining the ``velocity peak'' causes irrationality, especially in transient states. This transient state includes a transition from the j111 speed state to a coasting or engine braking state. At this time, by releasing the accelerator pedal, the vehicle shifts up to the higher speed side, but the magnitude of the shift speed in this case does not have a large effect on drivability. In other words, when the shifting speed is high and the speed is high, it accelerates, and when the shifting speed is low, I feel uneasy as if I suddenly lost the power. Decreasing the speed will slow down the shift in steady state, leading to worsening of fuel efficiency. The present invention has been made in view of these points, and it satisfies both responsiveness and drivability by determining a target shift speed and directly controlling the shift speed using that as a control target. Furthermore, it is an object of the present invention to provide a control device for a continuously variable transmission that improves drivability in a transient state when shifting to engine braking.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a speed change speed old/11
0 as a function of the flow rate Q, where the flow rate Q is the primary pressure Pp
, line pressure PL, gear speed r1 It is a function of the duty ratio when the control valve is operated in two positions, oil supply and oil drain, and each pressure PD and PL is a function of the gear ratio i, etc., so the gear shift speed is d i /d t is a function of the duty ratio and the gear ratio i. Further, the gear change speed di/dt is determined based on the deviation between the target gear ratio is and the actual gear ratio i in steady state. For this reason, a variable speed control valve is provided that operates in two positions, oil supply and oil drain, depending on whether the duty signal is on or off. Then, the gear shift speed 1fdi/dt is determined based on the coefficient set by the uneven stop of the target gear ratio is and the actual gear ratio i in steady state, and the rate of change of the engine load, and further, when shifting to the engine load-1 state. is the transmission speed (fJ d i , / t
The system is constructed so that the shift speed control valve is operated by supplementing so as to reduce L and determining the duty ratio based on this and the gear ratio 1.

[For production] Upper πiN%! Based on this information, a target speed change speed is determined, and the speed change speed is controlled using this as a control target. When shifting to the engine l-rake state, by setting the gear shift speed gradually, the gear can be shifted to a higher speed gear side, thereby making it possible to eliminate acceleration and anxiety. 【Example】

Embodiments of the present invention will be described below based on the drawings. In FIG. 1, an outline of a transmission system including a continuously variable transmission to which the present invention is applied will be explained. An engine 1 is connected to a clutch 2. The main shaft 5 of the continuously variable transmission 4 via the ship reverse switching device 3
Connect to. The continuously variable transmission 4 has a subshaft 6 arranged parallel to the main shaft 5, a primary pulley 7 on the main shaft 5, and a subshaft 6 on the main shaft 5.
The secondary pulley 8 is connected to aQG, and each pulley 7
．． 8 is equipped with hydraulic cylinders 9 and 10 on the movable side, and a drive belt 11 is wound around the windings 4-JG. Here, the primary cylinder 9 is set to have a larger pressure-receiving area, and the primary pressure causes the drive belt 11 to wrap around the pulley 7.8 so that the ratio of the diameter thereof is changed and the speed is continuously variable. Further, the subshaft 6 is connected to an output shaft 13 via a set of glue reduction gears 12, and the output shaft 13 is connected to the final 1!1 shaft 14. Drive wheel 16 via differential gear 15
It has been published on AW4. Next, the hydraulic control diameter of the continuously variable transmission 4 will be explained. It has an oil pump 20 driven by the engine 1, and the line pressure oil passage 21 on the discharge side of the oil pump 20 is connected to the secondary cylinder 10. Line pressure control well 22. The transmission speed control valve 23 communicates with the transmission speed control valve 23 , and the transmission speed control valve 23 communicates with the primary cylinder 9 via a line pressure oil passage 24 . The line pressure oil passage 21 further communicates with the regulator valve 25, and the oil passage 2 with constant regulator pressure from the regulator valve 25.
6 is the solenoid valve 27, 28 and the gear speed Ill
Each solenoid valve 27, 28 communicating with one side of #a valve 23
is turned on to exhaust pressure and turned off to output the regulator pressure PR in response to a duty signal from the control unit 40, and generates such a pulse-like control pressure. The pulse-like control pressure from the solenoid valve 27 is
It is averaged in the accumulator 30 and acts on the line pressure control 22. On the other hand, the pulse I-shaped control I pressure from the solenoid valve 2E% acts on the other shift speed control valve 23 as it is. , In addition, the reference numeral 29 in the figure is a doshin oil passage, and 31
is A Ile Pan, and 32 is A Risuis. The line pressure control valve 22 controls the line pressure PL based on the gear ratio i and the engine torque (2) using the averaged control pressure from the lenoid valve 27 (2). The gear change speed control valve 23 has a refueling position connecting the line pressure oil passage 21.24 and a line pressure oil passage 24 depending on the relationship between the regulator pressure and the pulse-like control pressure from the 1-lunoid valve 28.
Operates at the oil drain position to drain the oil. Then, depending on the duty ratio, the operating state of the 2 positions is changed to supply oil to the primary cylinder 9 or the flow of oil to the primary cylinder 9. ltQ is controlled to change the gear ratio i4r and also change the speed of change old/dt. That is, the required oil MV of the primary cylinder 9 is
It is determined mechanically and structurally in relation to V=r (
i ), and since the flow rate Q is the oil amount ■ differentiated with respect to time, Q = dv/dt = (df (i) /di)・(old/dt), and the flow IQ and the shifting speed dt/dt corresponds to the gear ratio 1 as a parameter. Therefore, the following formula is obtained. di/dt= f(Q, i) Also, primary cylinder internal pressure Pp, line pressure PL, deep field coefficient C1 power acceleration q, oil ratio! 1! Crushed γ. Valve refueling boat opening area Si, oil draining boat opening area So
In other words, the oil supply flow rate Qi and the oil discharge flow rate QO are Qo = c
-So [(2oPp > /Vli=a-8o (
Pp ) number Qi = a-5i (PL - Pp )'[a=c(
2g/γ) fleas]. Therefore, if the de:t -74 ratio (on/off ratio) is D and 4, then the average flow mQ of J cycles (refueling is assumed to be positive) is: Q=a (D-8i (PL-Pp) i-(1-D
)xSo (Pp) ~) If a, St, and So are constants, the following equation is obtained. Q= f(D, PL, Pp) Here, line PL is determined by gear ratio i and engine torque T! 11111, and the primary cylinder internal pressure P
Since p is determined by the gear ratio i and the line pressure PL, assuming that ■ is constant, barrel=f(D,i), and the following equation holds true. di/dt= f (D, , i > Therefore, when the formula is expanded, D= f (di/dt, i ), and from the above, it can be seen that the shift speed di/dt corresponds to the duty ratio. The duty ratio is
It is determined by the relationship between the speed change speed di/dt and the speed change ratio 1. On the other hand, the gear shift speed di/dt is the target gear ratio i in steady state.
Since it is based on the deviation between s and the actual gear ratio i,
The following formula holds true. rJi/+Jt=k(is-i) From this, for each gear ratio i, the gear shift speed d
Once i/dt is determined, the duty ratio can be determined based on it, and the shift speed control valve 23 is adjusted based on this duty ratio.
By shifting the operation, it becomes possible to perform gear ratio change speed control over the entire gear shift range between low gear and high gear. l5-1 in the above equation corresponds to the change in engine torque ΔT6, and the coefficient can be considered to represent the driver's intention to accelerate. Therefore, by making the coefficient k variable according to changes in engine load, it is possible to determine the shift speed di/dt during acceleration as well as during steady state. Furthermore, transient states and various operating states other than steady state and acceleration can be dealt with by correcting the fixed speed change speed based on the steady state. Therefore, the electrical control system shown in FIG. 2 is constructed based on the above-mentioned principle, and will be explained below. First, regarding the shift speed I control system U2, the primary pulley 7, secondary pulley 8. Each rotation speed sensor 41, 42, 43 and throttle opening sensor 44 of the engine 1 are activated. Then, in the control unit, rotation signals Nl), NS from both boolean rotation speed sensors 41, 42
is input to the actual gear ratio calculation unit 45, and 1 = Np/Ns
Find the actual gear ratio i. Further, the signal NS from the secondary pulley rotation speed sensor 42 and the signal θ from the throttle opening sensor 44 are input to the target gear ratio search section 46 . Here, a table shown in FIG. 3(B) is set based on the shift pattern shown in FIG. 3(2), and IS is searched from the values of NS and θ in this table. The signal θ of the throttle opening sensor 44 is detected by the acceleration detection section 51
is input to calculate the throttle opening change θ from dθ/dt, and based on this, a coefficient setting section 47 sets a coefficient k as a function of θ. Then, the actual gear ratio i of the actual gear ratio calculation unit 45
, the steady state target gear ratio is of the target gear ratio search unit 46 and the coefficient of the coefficient setting unit 47 are input to the gear shift speed calculation unit 48, and the gear shift speed di/dt is determined by di/dt=k (is-t). Calculated and its positive. The negative sign determines upshift or downshift. Next, as a correction during engine braking, a signal from an idle switch 52 that detects release of the accelerator is input to an engine brake detection section 53, which outputs an engine brake signal when the accelerator is released during driving. Further, there is a shift speed correction section 54 on the output side of the shift speed calculation section 48,
When the engine brake signal is input, the shift speed di
/dt is reduced by several percent, and the shift speed signal from the shift speed correction section 54 is further input to the duty ratio search section 44. As already mentioned here), duty ratio [) = f(
Based on the relationship di/dt, i), a table of duty ratios based on di/dt, i is set as shown in FIG. 3G), and the duty ratio is retrieved from this table. In this table, the value of the duty ratio is set to be smaller as the gear ratio 1 becomes smaller and there are 8 rows of high speed gears, and the shift speed di/dt becomes smaller. The duty ratio signal from the duty ratio search section 49 is input to the solenoid 28 via the drive section 50. Next, I will explain about the line pressure control system.Throttle opening sensor! The signal 8θ of J-44, the signal NeJ5 of the engine speed sensor 43, and the signal Ri of the actual gear ratio calculation unit 45 are input to the line pressure setting unit 55, and the target line pressure PL is set by the element of the actual gear ratio i under the engine torque. Establish. Then, the duty ratio setting section 56 calculates the duty ratio corresponding to the target line pressure PL, and this duty signal is used as the drive signal.
It is designed to be inputted to the solenoid valve 27 via JJM57. Next, the operation of the υ control device for the continuously variable transmission configured as described above will be explained. First, power from the engine 1 corresponding to the pedal depression is input to the primary pulley 7 of the continuously variable transmission 4 via the clamp 2 and the switching device 3, and the drive belt t-11,L-
The dynamic engine whose speed has been changed by the candari wheel 8 outputs an output, which is transmitted to the drive wheels 16 to drive the vehicle. Then, during the above-mentioned traveling, the target line pressure is set to be larger as the engine torque T is larger in the Iba gear where the value of the actual gear ratio i is larger at i-, j'+, and a duty signal corresponding to this is input to the solenoid valve 27. 11i1J 1
Generate one loaf and use the averaged pressure to control line pressure well 2.
By operating 2, the line pressure PL of the line pressure oil passage 21
As the gear ratio 1 becomes smaller and the engine torque T also becomes smaller, the line pressure PL is controlled to decrease by the same action. Pressing the pulley corresponding to 2 exerts a force. The line pressure PL is always supplied to the secondary cylinder 10, and the speed change speed is controlled by supplying and draining oil to the primary cylinder 9 using the speed change control valve 23. This will be explained below. First, the signals NpN from each sensor 41, 42 and 44
5. θ is read, the actual gear ratio i is determined by the gear change speed calculation unit 45 of the control unit 4o, the target gear ratio is is determined by the target gear ratio search group 4G, and the gear change speed is calculated by the gear change speed calculation unit 48 using these and the coefficient k. Find di/dt. Therefore, in an upshift where IS<1, di/dt becomes a negative value. Therefore, in the f-neity ratio search unit 49, di/dt and i
The duty ratio is searched based on. The duty signal is input to the solenoid valve 28 to generate a pulse-like control pressure, which causes the speed change speed control valve 28 to generate a pulse-like control pressure.
Repeat step 3 at two positions: oil supply and oil drain. Here, when the duty ratio becomes smaller, the shift speed control valve 23 operates for a longer time in the refueling position due to the off time, and the primary cylinder 9 is refueled, thus shifting up. On the other hand, when the duty ratio increases, the operating time at the oil draining position becomes longer due to the ON time, and the primary cylinder 9 drains oil.1. - This causes a downshift. And the speed change speed of the speed change ratio in this case,
Since di/dt corresponds to changes in the duty ratio, if the deviation between the target speed ratio is and the actual speed ratio i is small, the change in the duty ratio is small and the flow rate change in the primary cylinder 9 is small, so the speed change speed will change. is delayed. On the other hand, as the deviation between the target speed ratio is and the actual speed ratio i increases, the change in the flow rate of the primary cylinder 9 increases due to a change in the duty ratio, and the speed change speed becomes faster. In this way, the gear ratio is shifted up or down while changing the gear ratio change speed, and the gears are shifted steplessly over the entire range of the low and high speed gears. On the other hand, during acceleration in the steady operation, the acceleration detection section 51 detects the acceleration state based on the change θ of the accelerator opening, and sets the coefficient k in accordance with this. So, in case of sudden acceleration,
The shift speed di/dt becomes a large value, and the shift is downshifted at a fast shift speed to promote acceleration. On the other hand, during engine braking when the accelerator is released while driving, the target gear ratio IS is set to the high speed gear side as the accelerator opening degree Q decreases, and 1s-i becomes a negative value and is shifted up. By the way, since the engine brake signal from the engine brake detection section 53 is now used to correct di/dt to a smaller value in the shift speed correction section 54, the shift speed has become slower as shown by the broken line in FIG. Gradually shift by 7. Although one embodiment of the present invention has been described above, detection of engine brake may be performed using suction pipe negative pressure, and correction can also be made variable depending on the state of engine brake. It goes without saying that the effects of the embodiments can also be processed by software using a microcomputer. [Effects of R Light] As described above, according to the present invention, since the hydraulic control system has a configuration in which the speed change speed is controlled by a single speed change control valve, the structure is simple and the control is easy. It is. Since this is a method in which the gear shift speed is made to correspond to the duty ratio of the solenoid valve, and the duty ratio is determined based on the deviation between the target gear ratio and the actual gear ratio, and the gear shift speed is directly controlled, the control operation,
Good in terms of responsiveness etc. Since the gear change speed for upshifting to the high gear side is slowed down only during engine braking, there is no acceleration or anxiety during engine braking, improving drivability. Further, in the steady state, the predetermined speed change speed does not cause deterioration in fuel consumption, etc.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a hydraulic control system in an embodiment of the control device of the present invention, FIG. 2 is a block diagram showing the electrical control system, and FIG. 3 is a diagram showing a characteristic diagram and a table. 4... Continuously variable transmission, 7... Primary pulley, 8...
...Secondary pulley, 9...Primary cylinder,
DESCRIPTION OF SYMBOLS 10... Secondary cylinder, 11... Drive belt, 21.24... Line pressure oil path, 23... Shift speed control valve, 28... Solenoid valve, 40... Control unit, 45... ...Actual gear ratio calculation section, 46...: Target gear ratio search section, 4γ... Coefficient setting section, 48... Gear change speed calculation section, 49... Duty ratio search section, 52... Idle switch , 53... engine brake detection section,
54... Gear shift trace correction section.

Claims (1)

[Claims] A variable speed control valve is provided in the middle of the line pressure oil path to the primary cylinder, which operates in two positions, lubricating and draining, depending on on/off of a duty signal, and the variable speed control valve is set to the target in steady state. It is determined based on the deviation between the gear ratio and the actual gear ratio, and is corrected to reduce the gear shift speed when shifting to a higher gear during engine braking, and the duty ratio of the gear shift speed control valve is adjusted in accordance with the gear shift speed. Continuously variable transmission control device that sets the