JPH0563659B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a hydraulic control device for an automatic transmission, particularly to downshift control.

Prior art A brake and a one-way clutch are installed in series, and the D
Automatic transmissions that achieve low gears in the (drive) range by engaging this brake and one-way clutch can omit complex hydraulic control when downshifting from high gears to low gears; In order to use the lower gear as a gear, a separate brake is required in parallel to the series connection, which increases the axial dimension of the automatic transmission. Therefore, by using the separate brake for both the low speed gear in the D range and the engine braking, an automatic transmission with a reduced axial dimension by omitting the series connection between the brake and the one-way clutch has been provided. However, in this case, in order to prevent the shift shock and engine racing during downshifting, the underlap period is set, that is, the brake for the low gear is still released even after the frictional engagement device for the high gear is released. It is necessary to control the period of time that it remains in the state.

Also, the amount of increase in engine speed required during downshifting increases as the vehicle speed increases.
The appropriate length of the underlap period becomes longer as the vehicle speed is higher.

Regarding downshift control, Japanese Patent Publication No. 58-25175 discloses a spool valve type control valve that reduces the servo oil pressure of a friction engagement device for a high speed gear when the servo oil pressure of a friction engagement device for a low gear rises to a predetermined level. , and another control valve in the form of a spool valve that increases the servo oil pressure of the frictional engagement device for low speed when the servo oil pressure of the frictional engagement device for high speed is further reduced to another predetermined level. In this case, what is controlled is the overlap period, that is, the period in which the low-speed friction engagement device and the high-speed friction engagement device are in the engaged state at the same time, and the spool valve type control valve is controlled by the hydraulic control device. In addition, there is a problem that control accuracy is poor due to variations in the transmission time of control pressure to the control valve.

In Japanese Patent Application Laid-open No. 58-30555, for example, when an upshift from the first gear to the second gear occurs due to switching from the L range to the D range, the engagement of the frictional engagement device for the second gear is changed to the first gear. In order to moderate the shift impact by appropriately delaying the release of the first gear friction engagement device,
This indicates that the supply of hydraulic medium to the second speed friction engagement device is blocked for a predetermined period of time. The optimal predetermined time varies from vehicle to vehicle due to variations in engines, automatic transmissions, and hydraulic controls.
With this control device, it is difficult to alleviate the shift impact of all automobiles.

Japanese Patent Laid-Open No. 58-37357 discloses that in downshift control of a parallel shaft gear type automatic transmission, the intake throttle opening is increased during the period when the electromagnetic clutch between the engine and the automatic transmission is released, and the engine rotation is controlled. However, this technology is difficult to apply to automatic transmissions using hydraulic friction engagement devices, and requires an actuator to control the throttle opening, making the device complex. becomes.

Purpose of the Invention An object of the present invention is to accurately control the underlap period during downshift control in relation to vehicle speed without being affected by variations in control pressure transmission time or variations in the engine, etc., and to have a simple configuration. An object of the present invention is to provide a hydraulic control device for an automatic transmission.

Means for Achieving the Object In order to achieve this object, the hydraulic control device of the present invention includes a first frictional engagement device that is held in an engaged state in a first gear, and a first friction engagement device that is held in an engaged state in a first gear. a second frictional engagement device that is held in an engaged state at a second gear that is one speed higher; A hydraulic control device for an automatic transmission, comprising: a shift valve for downshifting from a second gear to a first gear by connecting the device to a drain; and a vehicle speed detection means for detecting vehicle speed. , an oil temperature detection means for detecting oil temperature, a throttle opening detection means for detecting a throttle opening, a vehicle speed detected by the vehicle speed detection means, an oil temperature detected by the oil temperature detection means, and a throttle opening detection means. a reference rotation speed setting means that sets a reference rotation speed to a value that increases as each value of the throttle opening degree detected in the above increases; and an electromagnetic valve that controls the supply of hydraulic pressure to the first frictional engagement device; a rotational speed detection means for detecting the rotational speed of the engine; and a rotational speed detected by the rotational speed detection means when the shift valve executes a downshift from the second gear to the first gear. and a solenoid valve control means for controlling the solenoid valve so as to limit the supply of hydraulic pressure to the first frictional engagement device until the rotational speed reaches the reference rotational speed set by the reference rotational speed setting means. It is characterized by

Operation When the shift valve is switched from the position corresponding to the second gear to the position corresponding to the first gear, the second frictional engagement device is connected to the drain and its oil pressure begins to decrease, until finally The second frictional engagement device is in the released state.

On the other hand, in the first friction engagement device, even after the shift valve is switched, the supply of hydraulic medium is restricted by the electromagnetic valve until the engine rotation speed reaches the reference rotation speed, and the second friction engagement device After the coupling device is released, it remains in the released state, resulting in an underlap period.
When the engine rotation speed reaches the reference rotation speed, the restriction on the supply of hydraulic medium to the first frictional engagement device by the solenoid valve is lifted, and the first frictional engagement device is supplied with hydraulic medium and immediately engages. A state is reached, and the first gear stage is generated.

Effects of the Invention In the present invention, the actual engine rotation speed is detected.
When the actual engine speed increases to an appropriate value,
Since the end of the underlap period is controlled, an appropriate underlap period can be set without being affected by variations in the engine and automatic transmission.

The higher the vehicle speed, the greater the amount of increase in engine rotational speed required during the underlap period during a downshift, and the higher the oil temperature and the greater the throttle opening, the faster the hydraulic pressure supply speed becomes. Therefore, in the present invention, the vehicle speed and other conditions that affect the oil supply and discharge speed are reflected in the reference engine speed when the solenoid valve is switched. It is possible to obtain an appropriate engine speed by adjusting according to the state of the engine.

In the present invention, the underlap period during downshifting is controlled by controlling the solenoid valve with an electric signal, so the configuration can be simplified compared to a hydraulic control device that uses a spool valve type control valve, and the control High control accuracy can be obtained by eliminating the influence on the underlap period from variations in pressure transmission time.

In a preferred embodiment, the electromagnetic valve is a valve that opens and closes an oil passage connecting a hydraulic medium oil passage from the shift valve to the first friction engagement device to a drain, and the values related to the vehicle speed are a coefficient K and a vehicle speed V. It is expressed as the product K·V of , and K is set as a function of the intake throttle opening. When the output torque of the engine changes, the appropriate length of the underlap period also changes, so by setting K·V to a value related to the vehicle speed, the length of the underlap period can be adjusted according to the intake throttle opening. In other words, as the intake throttle opening θ increases, the time from the start of supply of hydraulic medium to the first frictional engagement device until the first frictional engagement device actually starts engaging, that is, the response delay, becomes shorter. Therefore, this is compensated for by setting K as a function of the intake throttle opening θ.

Preferably, the factor K is set as a function of the temperature of the hydraulic medium. When the oil temperature is low, the viscosity of the hydraulic medium is high and the flow speed of the hydraulic medium in the oil path is reduced. Therefore, the lower the oil temperature is, the lower the value of K is set to the first frictional engagement device. To quickly release restrictions on the supply of hydraulic medium, thereby compensating for adverse effects on oil temperature.

Example The present invention will be described with reference to the embodiments shown in the drawings.

In FIG. 1, an oil pump 10 sucks oil in an oil pan 12, pressurizes it, and discharges it.
Other hydraulic control circuits 14 include elements such as a primary regulator valve, which generates line pressure P in oil passage 16 . The 2-3 shift valve 20 has a port 2 connected to a line pressure oil passage 16 as a supply pressure oil passage.
2, 24, drains 26, 28, and other ports 30, 32.
ports and drains 22, 24, 2 in relation to
6, 28, 30, and 32. Third
The speed clutch 34 is held engaged in third gear and is connected to the port 30 via an oil line 36. The accumulator 38 is connected to the oil passage 36, and an orifice 40 and a check valve 42 are provided in parallel with each other in the middle of the oil passage 36. The check valve 42 opens to allow oil in the third gear clutch 34 to flow toward the port 30. 2nd speed brake 4
4 is held in an engaged state in the second speed and is connected to the port 32 via an oil passage 46. The accumulator 48 is connected to the oil passage 46 and
An orifice 50 and a check valve 52 are provided in parallel with each other in the middle. The check valve 52 is the second
It opens when the oil of the speed brake 44 flows toward the port 32. The discharge oil passage 54 branches from the oil passage 46 between the port 32 and the orifice 50,
Connect the oil line 46 to the drain. The vehicle speed sensor 62 detects the vehicle speed V, the throttle opening sensor 64 detects the intake throttle opening θ, and the shift position sensor 66 detects the shift position such as D (drive) or R (reverse) selected by the driver. The pattern select switch 68 detects the driving pattern such as economy (economical driving) and power (output driving) selected by the driver, and the engine rotational speed sensor 70 detects the engine rotational speed and oil temperature. The sensor 72 detects the temperature T of the oil in the oil pan 12. The CPU 76 controls a solenoid valve 78 as an electromagnetic valve based on input signals from sensors or switches 62, 64, 66, 68, and 70 using electrical signals. Solenoid valve 78 is solenoid 8
0, and the discharge oil passage 5 in relation to the solenoid 80.
It has a valve body 82 that opens and closes 4.

The control performed by the CPU 76 will be explained with reference to FIG. In Fig. 2, Pc is the servo oil pressure of the third gear clutch 34, and Pb is the second gear clutch 34 servo oil pressure.
This is the servo oil pressure of the speed brake 44.

At time t1, the 2-3 shift valve 20 was previously held at the high speed position, the port 30 was connected to the port 22, and the port 32 was connected to the drain 28.
connected to. As a result, the third speed clutch 34 is supplied with line pressure P from the line pressure oil passage 16 and is held in an engaged state, and the oil in the second speed brake 44 is drained from the drain 28 and the second speed clutch 34 is maintained in an engaged state. Since the automatic transmission brake 44 is held in a released state, the automatic transmission is in the third gear state.

At time t1, the 2-3 shift valve 20 is switched from a high speed position to a low speed position. This switching is performed by controlling the control pressure acting on the spool of the 2-3 shift valve 20 using a solenoid valve (not shown). This switching connects port 30 to drain 26 and port 32 to port 24, so
The servo oil pressure Pc starts to decrease from time t1. Even after the 2-3 shift valve 20 is switched, the solenoid 78 opens the discharge oil passage 54 until the engine rotational speed Ne reaches K·V, so that the line pressure P in the line pressure oil passage 16 is delivered to the port 32. Despite this, the servo oil pressure Pb is maintained at zero, and the second speed brake 44 is prevented from engaging. However, K is a coefficient and V is a vehicle speed.

When Ne reaches K·V at time t2, the solenoid valve 78 closes the drain oil passage 54. As a result, the servo oil pressure Pb starts to rise from time t2,
At time t3, when time T has elapsed from time t2, the second speed brake 44 is in a semi-engaged state.

After the servo oil pressure Pc has decreased appropriately, time t3
Since this is an underlap period in which the third speed clutch 34 and the second speed brake 44 are both released, the engine rotational speed can quickly rise to an appropriate value.

FIG. 3 shows the relationship between the coefficient K and the intake throttle opening θ. As the throttle opening θ increases, the response delay time T shown in FIG. 2 becomes shorter, so the coefficient K is increased as the throttle opening θ increases. In addition, as the oil temperature To decreases, the viscosity of the oil increases, and the flow speed of the oil in the oil passage decreases, causing the time T shown in Fig. 2 to increase.As the oil temperature To decreases, the coefficient K decreases.

FIG. 4 is a flowchart of a speed change control routine according to the control explained in FIG. When the ignition switch is turned on (step 90), 3→2
The downshift flag F is reset as initialization (step 92). In the main routine (step 94), vehicle speed V and intake throttle opening θ
Calculate the indicated gear based on. If there is an instruction to downshift from 3 to 2, that is, if the previously calculated instructed gear position is 3rd gear and the currently calculated instructed gear position is 2nd gear (the judgment in step 98 is
YES), flag F is set (step
100), otherwise (the decision in step 98 is
(NO), the drive control of the gear position control solenoid valve is immediately performed (step 120). When F=1 (determination in step 96 is F=1), vehicle speed V, engine rotation speed Ne, throttle opening θ, and oil temperature To
(steps 102, 104, 106, 108), calculate the coefficient K based on θ, To (step 110),
Compare Ne with K and V (step 112). Ne＜
If Ne≧K.V, turn on the underlap control solenoid valve 78, that is, open the discharge oil passage 54 (step 114); if Ne≧K.V, turn off the underlap control solenoid valve 78, That is, after closing the drain oil passage 54 (step 116), F is reset (step 118).

FIG. 5 is a functional block diagram of the present invention. The coefficient calculating means 130 calculates the throttle opening θ and the oil temperature.
The coefficient K is calculated based on To, the multiplier 132 calculates the product K·V of the coefficient K and the vehicle speed V, and the comparing means 134 compares K·V with the engine rotational speed Ne.
The driving means 136 operates the underlap control solenoid valve 7 during a period when Ne has not yet reached K.V.
8 to open the discharge oil passage 54, and turn on the Ne
After reaching K.V, the underlap control solenoid valve 78 is turned off and the discharge oil passage 54 is closed.
Oil at line pressure P is guided to the second speed brake 44.

In the embodiment, the solenoid valve 78 is provided in the discharge oil passage 54, but it may be of a type that limits the supply of oil to the second speed brake 44 by opening and closing the oil passage 46. In the embodiment, a downshift from third speed to second speed has been described, but it goes without saying that the present invention can also be applied to control related to other downshifts.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of an embodiment of the present invention, Figure 2 is a diagram explaining the control performed by the CPU in Figure 1, and Figure 3 is a graph showing the relationship between intake throttle opening and coefficient. 4 is a flowchart of a speed change control routine according to the control shown in FIG. 2, and FIG. 5 is a functional block diagram of the present invention. 16... Line pressure oil path, 20... 2-3 shift valve, 26... Drain, 34... 3rd gear clutch, 44... 2nd gear brake, 62... Vehicle speed sensor, 70... Engine Rotational speed sensor, 76...
CPU, 78... Solenoid valve, 134... Comparison means, 136... Drive means.

Claims (1)

[Claims] 1. A first frictional engagement device that is held in an engaged state in a first gear, and an engaged state in a second gear that is one gear higher than the first gear. A second frictional engagement device held in A hydraulic control device for an automatic transmission having a shift valve that executes a downshift to a first gear, comprising: a vehicle speed detection means for detecting vehicle speed; an oil temperature detection means for detecting oil temperature; and a throttle opening degree. the vehicle speed detected by the vehicle speed detection means, the oil temperature detected by the oil temperature detection means, and the throttle opening detected by the throttle opening detection means. a reference rotational speed setting means for setting a reference rotational speed of the engine; a solenoid valve for controlling the supply of hydraulic pressure to the first frictional engagement device; a rotational speed detection means for detecting the rotational speed of the engine; and the shift valve. The rotational speed detected by the rotational speed detection means reaches the reference rotational speed set by the reference rotational speed setting means when downshifting from the second gear to the first gear. and a solenoid valve control means for controlling the solenoid valve so as to limit the supply of hydraulic pressure to the first frictional engagement device.