JPH04131560A - Line pressure control device for automatic transmission - Google Patents

Abstract

PURPOSE:To improve the performance of line pressure control at the time of speed change by providing the control characteristic of a line pressure control means with a transfer function of a reverse characteristic to the transfer function of a hydraulic system from a line pressure actuator to each speed change element. CONSTITUTION:The line pressure to be supplied to a hydraulic circuit for controlling each speed change element on the basis of speed change conditions is set by a line pressure setting means at the time of speed change. A line pressure control means outputs an output signal corresponding to the set line pressure to a line pressure actuator so as to drive the line pressure actuator. In this case, the transfer function of the line pressure control means is to have the reverse characteristic of the transfer function of a hydraulic supply system from the line pressure actuator to each speed change element in a transmission so that the output from the line pressure control means in relation to the set line pressure is made the output value with response delay in the hydraulic supply system taken into account, thus supplying appropriate line pressure to each speed change element without response delay.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a line pressure control device for controlling line pressure during gear shifting of an automatic transmission for an automobile.

<Conventional technology> In automatic transmissions for automobiles, line pressure is obtained by regulating the discharge pressure of the oil pump, and this is supplied to the hydraulic circuit to control the operating hydraulic pressure of the torque converter and various speed changes in gear type transmissions. This line pressure is controlled to the appropriate oil pressure according to the engine output, which is the operating oil pressure of the element.

Namely, a torque converter in an automatic transmission.

The line pressure, which is the source of the working oil pressure for various transmission elements, needs to be adjusted to the appropriate oil pressure depending on the engine output. If the oil pressure is higher than the appropriate oil pressure during gear shifting, the torque transmission efficiency will increase.
Engine vibrations and gear change shocks are transmitted to the output shaft, increasing noise and vibration. Furthermore, if the oil pressure is lower than the appropriate oil pressure during gear shifting, slipping occurs, reducing transmission efficiency, causing a feeling of delayed gear shifting, deteriorating the durability of the automatic transmission, and further deteriorating fuel efficiency.

Therefore, conventionally, there is a map that predetermines the optimal line pressure according to the throttle valve opening, etc., and the line pressure is searched and set from the map according to the shifting conditions at that time, and the line pressure is set based on this map. Line pressure was controlled by driving a pressure actuator (see Japanese Unexamined Patent Publication No. 62-9054, etc.).

<Problem to be solved by the invention> However, due to the inherent response delay depending on the response characteristics of the line pressure actuator, the viscosity of the oil, the length of the hydraulic circuit, etc.
It exists in the line pressure supply hydraulic circuit system. Therefore, there is a delay between when the output corresponding to the set line pressure is generated to the line pressure actuator and when the set line pressure is transmitted to the various speed change elements in the transmission, as shown in Figure 9. arise. For this reason, real-time feedback control of line pressure was difficult. Also, even if you try to change the line pressure during a shift, the followability is poor, so it is difficult to delicately control the line pressure in response to fluctuations in input shaft torque during a shift, so it is necessary to finely control the line pressure during a shift. That was difficult.

The present invention was made in view of the above circumstances, and takes into account the response delay of the hydraulic supply system including the line pressure actuator.
The purpose is to improve line pressure control performance during gear shifting by correcting the output to the line pressure actuator.

<Means for Solving the Problems> For this reason, the present invention, as shown in FIG. A line pressure control device for an automatic transmission, comprising: line pressure control means for generating an output signal corresponding to a set line pressure to drive a line pressure actuator to control the line pressure supplied to the hydraulic circuit; , the control characteristics of the line pressure control means,
The hydraulic pressure supply system from the line pressure actuator to each transmission element has a transfer function with inverse characteristics.

<Operation> In this configuration, during gear shifting, the line pressure setting means sets the line pressure supplied to the hydraulic circuit that controls each gear shifting element based on the gear shifting conditions.

The line pressure control means drives the line pressure actuator by outputting an output signal corresponding to the set line pressure to the line pressure actuator. Here, since the transfer function of the line pressure control means or the transfer function of the hydraulic pressure supply system from the line pressure actuator to each transmission element in the transmission is inverse, the line pressure is controlled with respect to the set line pressure. The output from the means takes into account the response delay in the hydraulic pressure supply system, and it becomes possible to supply appropriate line pressure to each transmission element without response delay.

<Example> Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 2 showing the configuration of this embodiment, an automatic transmission 2 is provided on the output side of the engine 1. The automatic transmission 2 includes a torque converter 3 interposed on the output side of the engine 1, a gear type transmission 4 connected via the torque converter 3, and a combination of various speed change elements in the gear type transmission 4. and a hydraulic actuator 5 for performing a release operation. Although the hydraulic pressure applied to the hydraulic actuator 5 is ON/OFF controlled via various electromagnetic valves, only shift electromagnetic valves 6A and 6B for automatic gear shifting are shown here.

Here, the torque converter 3 and the hydraulic actuator 5
An oil pump 7 driven by the input shaft of the gear transmission 4 is used to obtain line pressure, which is the working oil pressure for the orifice 8. Electromagnetic valve9. A pressure modifier valve IO and a pressure regulator valve 11 are provided.

The electromagnetic valve 9 is duty controlled as described later, and obtains pilot pressure based on the discharge pressure of the oil pump 7 guided through the orifice 8. The pressure modifier valve IO amplifies the pilot pressure. The pressure regulator valve 11 regulates the discharge pressure from the oil pump 7 to a line pressure proportional to the pilot pressure from the pressure modifier valve 10, and sends it to a hydraulic circuit such as the torque converter 3 and the hydraulic actuator 5. here,
The hydraulic supply system from the oil pump 8, including the electromagnetic valve 9, to the torque converter 3 and various speed change elements inside the automatic transmission 4 has a response based on the mechanical response delay of each valve, oil viscosity, hydraulic circuit length, etc. There is a delay.

The control unit 12 has a built-in microcomputer, and controls the line pressure by duty-controlling the electromagnetic valve 9 based on signals from various sensors.

As the various sensors mentioned above, a potentiometer type throttle sensor 14 is provided which detects the opening degree TV○ of the throttle valve 13 of the intake system of the engine 1.

Further, a crank angle sensor 15 is provided on the crankshaft of the engine 1 or a shaft that rotates in synchronization with the crankshaft. The signal from the crank angle sensor 15 is, for example, a pulse signal for each reference crank angle, and the engine rotational speed N is calculated from the period thereof.

In addition, a rotation signal is obtained from the output shaft of the automatic transmission 2 to determine the vehicle speed v.
A vehicle speed sensor 16 for detecting SP is also provided.

Next, line pressure control by the control unit 12 will be explained according to the flowchart in FIG.

In step 1 (indicated by Sl in the figure; the same applies hereinafter), it is determined whether or not the gear is being shifted. At this point, if the gear is not changing,
Proceeding to step 2, the optimum line pressure PL is determined in advance according to the throttle valve opening TVO by referring to a normal map, and the line pressure PL is searched and set based on the actual throttle valve opening TVO. Then, the process proceeds to step 11, where a duty corresponding to this line pressure PL is output, and the electromagnetic valve 9
Obtain the optimum line pressure by driving. If the gear is being changed, steps 3 to 10 are executed and the process proceeds to step 11 in order to control the line pressure during the gear change.

In step 3, the type of gear change is determined. Here, based on the signals from the throttle sensor 14 and the vehicle speed sensor 15, the speed change mode (1st speed → 2nd speed, 2nd speed,
3rd speed, etc.), and further, based on the searched shift form and the throttle valve opening degree TVO detected by the throttle sensor 14, a preset shift type shown in FIG. 4 is determined. Search for the type of shifting from the map. The type of shift is indicated by an integer number including 0.

Next, in step 4, the phase during gear change is determined.

In this embodiment, the phases during gear shifting are divided into 1 to 3 phases depending on the change in engine rotational speed N, as shown in FIG.
Engine rotation speed N detected by crank angle sensor 15
The phase transition from 1 phase to 2 phase and 2 phase to 3 phase is determined by the change in . That is, upon generation of a shift command, first a determination is made as to phase 1, then it is determined that the phase has shifted from phase 1 to phase 2 when the engine rotation speed N decreases, and then it is determined that the phase 1 has shifted to phase 2 when the engine rotation speed N has increased. At this point, it is determined that the phase has shifted from phase 2 to phase 3.

Then, the process proceeds to steps 5 to 7, respectively, based on the phase determination result during the shift, and the type of shift determined in step 3 and step 4 are determined from the map shown in FIG. Based on the phase determination result, the target line pressure PL at that time is searched. For example, the type of gear change or 0
If the shift mode is 1st speed → 2nd speed, and the throttle valve opening TVO is 1/16, then the target line pressure PLT in the 1st phase is Pl, and in the 2nd phase, the target line pressure is P1. Pressure P
LT becomes P2, and the target line pressure PLT during 3-phase is P
, becomes.

Once the target line pressure PLT is set in this way, steps 8 to 10 are executed to calculate the corrected line pressure PL for the target line pressure PLT.

Here, a method of calculating the corrected line pressure PL when the target line pressure PLT is given will be explained.

In consideration of the response delay of the hydraulic pressure supply system, the transfer function G+(s) in the control unit 12 is set to have an inverse characteristic to the transfer function 02(S) of the hydraulic pressure supply system. That is, the relationship is Gl(S)=02-'(s). When the response characteristic of the hydraulic pressure supply system is a second-order lag system, it is as follows. However, S is the Laplace operator, a, b.

K is a constant.

There is a relationship of G + (s) = 02-' (S), G + (s) = (S2 + 2abS + b2), where the input signal of the control unit 12 is
, the output signal is Y (s), and by Laplace inverse transformation, it becomes, where x(t) corresponds to the target line pressure PLT, y(t) corresponds to the corrected line pressure PL, and the target line The output line pressure when pressure is applied, that is, the corrected line pressure can be calculated from the above equation.

For reference, FIGS. 7 and 8 show graphs of examples of response correction using general inverse characteristics. These examples show the case of a target value or a ramp function, and FIG. 7 shows the case of a first-order lag system, and FIG. 8 shows the case of a second-order lag system.

Therefore, in step 8, the target line pressure PLT is calculated from the current target line pressure PLT and the previous target line pressure PLT0.
Find the first differential DPL, (=PLT-PL,.).

In step 9, the first derivative DPLT of the current target line pressure PLT obtained in step 8 and the previous first derivative DPLT are calculated.
o and the second derivative DDPL of the target line pressure PLT?
Find (=DPL, -DPL,.).

In step 10, the corrected line pressure PL is determined by the following equation.

In step 11, a duty corresponding to the corrected line pressure PL obtained in step 10 is output.

In this way, by providing the control unit 12 with a characteristic opposite to the delay characteristic of the hydraulic pressure supply system, the line pressure during gear shifting can be controlled without response delay.

<Effects of the Invention> As explained above, according to the present invention, the output value corresponding to the target line pressure to be applied to the line pressure actuator of the hydraulic supply system is corrected using an inverse characteristic with respect to the transfer function of the hydraulic supply system. With this configuration, line pressure response delays caused by the delay characteristics of the hydraulic pressure supply system can be suppressed, so line suppression can be finely and accurately performed during gear shifts, and line pressure control performance can be improved.

[Brief explanation of drawings]

Fig. 1 is a block diagram explaining the present invention in detail, Fig. 2 is a system diagram showing an embodiment of the present invention, Fig. 3 is a flowchart of a line pressure control routine, and Fig. 4 is an example of a shift type map. Figure 5 is a diagram showing an example of the target line pressure map for each phase during gear shifting, Figure 6 is a diagram showing classification of each phase during gear shifting, and Figure 7 is a diagram of a general first-order lag system. FIG. 8 is a correction characteristic diagram for a general second-order lag system, and FIG. 9 is an explanatory diagram of conventional problems. 1... Engine 2... Automatic transmission 3... Torque converter 8... Oil pump 9... Solenoid valve 10... Pressure modifier valve 11
...Pressure regulator valve 12...Control unit 14...Throttle sensor patent applicant Japan Electronics Co., Ltd.

Claims (1)

[Claims] A line pressure setting means for setting line pressure supplied to a hydraulic circuit that controls each transmission element based on transmission conditions, and a line pressure setting means for generating an output signal corresponding to the set line pressure to drive a line pressure actuator to In a line pressure control device for an automatic transmission, which includes a line pressure control means for controlling line pressure supplied to a circuit, the control characteristics of the line pressure control means include hydraulic pressure supply from the line pressure actuator to each transmission element. A line pressure control device for an automatic transmission, characterized in that it has a transfer function with inverse characteristics to the transfer function of the system.