JP2767872B2 - Shift pressure control device for automatic transmission - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift hydraulic pressure control device for an automatic transmission, and more particularly, to a shift hydraulic pressure control device supplied to a newly engaged friction element during a downshift.

2. Description of the Related Art Generally, an automatic transmission mounted on a vehicle includes a plurality of planetary gear sets as a transmission gear, and connects a plurality of friction elements such as a clutch and a brake by connecting the components of the planetary gear set. Alternatively, by releasing and switching, various speeds can be obtained.

By the way, a line pressure controlled by a hydraulic pressure control circuit is used as a working hydraulic pressure for fastening the friction element, and the line pressure is changed according to an engine load (throttle opening), and the engine load is large. Occasionally, the line pressure is increased to prevent the friction element from slipping.

Therefore, when the automatic transmission is shifted, the line pressure is adjusted according to the engine load, and is removed from the frictional elements that were engaged before the gear shift, and is attempted to be engaged after the gear shift. The friction element is supplied to the friction element to switch the friction element.

For this reason, a high line pressure is supplied to the friction element that is to be newly engaged at the time of the step-down shift, and if such a high line pressure is supplied at once, a large engagement shock is applied to the friction element. This causes a shift shock.

Therefore, in a conventional automatic transmission, for example,
As disclosed in Japanese Patent No. 83539, by providing an orifice in the hydraulic pressure supply circuit of the low clutch as a friction element and increasing the throttle amount, the hydraulic pressure supply during shifting is performed slowly, and the engagement shock is reduced. It is supposed to be.

However, when the supply or elimination of the hydraulic pressure is always performed via the orifice, the engagement time of the friction element is prolonged more than necessary, and the downshift by depressing the accelerator pedal, that is, the driving wheel Since the cutoff state of the rotation input from the side becomes longer, the rise of the engine speed is slowed down, which causes a shift lag.

Therefore, in the above-mentioned conventional automatic transmission, a timing valve is provided to bypass the orifice and communicate with the hydraulic pressure supply circuit, that is, a timing valve for reducing the throttle amount is provided. The friction element is fastened.

SUMMARY OF THE INVENTION However, in such a conventional variable speed hydraulic pressure control device, the operation time point of the timing valve is determined by the vehicle speed, and the timing of reducing the throttle amount at a high vehicle speed is advanced, and at a low vehicle speed, the timing is reduced. Was supposed to.

For this reason, in the shift diagram in FIG. 11, during a downshift in the A direction, that is, during a normal downshift that does not involve the depressing of the accelerator pedal, an appropriate shift with little shift shock at low vehicle speed is possible. It becomes
At the same low vehicle speed, at the time of downshifting in the direction B in the drawing, that is, at the time of stepping downshifting, the engagement timing of the frictional elements is delayed, and a rapid increase in engine rotation cannot be expected, so that a large shift lag is felt. There were challenges.

Accordingly, the present invention has been made in view of the above-described conventional problems, and has an automatic transmission that can reduce a shift lag during a normal downshift, promote an increase in engine speed during a downshift, and reduce a shift lag. It is an object of the present invention to provide a variable hydraulic pressure control device.

Means for Solving the Problems In order to achieve such an object, the present invention comprises a plurality of hydraulically operated friction elements a and b, as shown in FIG. In the automatic transmission, which switches the transmission gears and appropriately changes and outputs the input rotation from the power source c, the automatic transmission is provided in the hydraulic pressure supply circuit d of the friction element a which is engaged at the time of the downshift, and supplies the hydraulic pressure. Throttle means e for switching between a small throttle amount for performing the normal operation and a large throttle amount for performing the supply of the fluid pressure slowly, a downshift detecting means f for detecting a downshift, and an accelerator for detecting an accelerator opening degree Opening degree detecting means g, accelerator changing rate detecting means h for detecting a changing rate of the accelerator opening degree, vehicle speed detecting means i for detecting a vehicle speed, and a changing rate of the accelerator opening degree at the time of a downshift corresponds to the accelerator opening degree and the vehicle speed. Set according to And a diaphragm amount switching means j for shortening the timing of switching the diaphragm amount of the variable diaphragm means e to a small value when the value is equal to or more than a predetermined value.

In addition, the limit value of the accelerator change rate for switching the variable throttle means e is input to the throttle amount switching means j by mapping in advance the accelerator opening and the vehicle speed as dimensional axis elements, and the limit value is determined along the map. It is desirable to control the aperture amount switching means j.

With the above-described configuration, in the shift hydraulic pressure control device for the automatic transmission according to the present invention, the accelerator opening is detected by the accelerator change rate detecting means h because the accelerator pedal is rapidly depressed during the downshift. The rate of change increases, but the rate of change is compared with a predetermined value set in accordance with the accelerator opening and the vehicle speed by the throttle amount switching means j. Set earlier.

Therefore, when the accelerator change rate is equal to or more than a predetermined value, the hydraulic pressure supplied to the friction element a increases quickly, and the friction element a is fastened, and the rotation of the power source c is performed by the rotation input on the drive wheel side. Speed quickly reaches the rotational speed corresponding to the gear ratio after the downshift, and the shift period is shortened, and thus the shift lag is reduced.

If the rate of change is smaller than a predetermined value, the switching time point of the variable throttle means e is set later than the timing, so that control focusing on reduction of shift shock can be performed.

Further, by performing the switching of the variable aperture means e in accordance with the map inputted to the aperture amount switching means j, quick control becomes possible and the circuit configuration of the aperture amount switching means j is simplified. Be transformed into

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

That is, FIG. 2 is a schematic view of a transmission hydraulic pressure control device for an automatic transmission according to an embodiment of the present invention. Reference numeral 10 denotes a control unit, which is controlled by a control signal output from the control unit 10. / T hydraulic pressure control is performed.

The automatic transmission A / T has, for example, a power train shown in FIG. 3 and is coupled to an engine E as a power source via a torque converter T / C having a lock-up clutch LU / C. The rotation is output to a drive wheel side (not shown) via the torque converter T / C and the automatic transmission A / T.

Incidentally, the change gear train of the automatic transmission A / T, the front sun gear S _1, the front pinion gear P _1, the front internal gear R _1, a front planetary gear set G ₁ consisting of the front planet carrier PC _1, rear sun gear S ₂ , constructed by Riabiniongia P _2, the rear internal gear R _2, and a rear planetary gear set G ₂ consisting of the rear planet carrier PC _2, these two sets of planetary gear G _1, G ₂ are tandem arranged Have been.

As shown in the figure, the power train including the transmission gear train includes reverse clutch R / C, high clutch H / C, low clutch L / C, low & reverse brake L & R / B, hand brake B / B, etc. A friction element is incorporated, and in addition to these friction elements, a one-way clutch OWC is incorporated.

By the way, in the power train having such a configuration, as shown in Table 1 below, various frictional elements are engaged and released by a line pressure supplied from a hydraulic control circuit described later, so that various speeds can be obtained. It is supposed to be.

In the table, a circle indicates a fastened state, and a blank indicates a released state.

The bunt brake B / B is actuated by a band servo 17 described later having a fastening chamber and a release chamber, and the bunt brake B / B is fastened by supplying hydraulic pressure to the fastening chamber. When the hydraulic pressure is supplied to the release chamber, the bunt brake B / B is released.

FIG. 4 shows a hydraulic control circuit for controlling the hydraulic pressure supplied to each of the friction elements, and the friction elements are fastened or released by the control hydraulic pressure supplied from the hydraulic control circuit.

In the above hydraulic pressure control circuit, oil pump O / P, pressure regulator valve 1, manual valve 2, throttle valve 3, detent & face safe valve 4, kick down modulator valve 5, pressure modifier valve
6, Cut back valve 7, Backup valve 8, Pilot valve 9, 1-2 shift valve 10, 2-3 Shift valve 11,
3-4 shift valve 12, 1-2 solenoid valve 13, 2-3
Solenoid valve 14, 3-4 solenoid valve 15, accumulator valve 16, band servo 17, servo release timing valve 18, low clutch accumulator 19, high clutch control valve 20, high clutch solenoid valve 21, large clutch timing valve 22, low clutch Solenoid valve 23,4-3 Timing valve 24,3-2
Timing valve 25, governor valve 26, torque converter regulator valve 27, lock-up valve 28, lock-up solenoid valve 29, I range reducing valve
The valves 30 are connected to the friction elements and the torque converter T / C via the illustrated circuit.

In the above hydraulic control circuit, the 1-2 solenoid valve 13, the 2-3 solenoid valve 14, the 3-4 solenoid valve
By turning ON and OFF of 15, the 1-2 shift valve 10, 2-3 shift valve 11, and 3-4 shift valve 12 are switched in the vertical direction in the figure as shown in Table 2, so that as shown in Table 1 above. The supply and elimination of hydraulic pressure are performed on the friction elements that are engaged and released at each shift speed.

The detailed configuration and function of each component of the hydraulic control circuit are the same as those described in Japanese Patent Application Laid-Open No. 62-83539, and a detailed description thereof will be omitted.

The ON and OFF signals output to the 1-2 solenoid valve 13, 2-3 solenoid valve 14 and 3-4 solenoid valve 15 are determined by, for example, the vehicle speed and the accelerator opening as shown in FIG. Is controlled according to the shift schedule.

By the way, in the power train of the present embodiment, at the time of the downshift from the fourth speed to the third speed in the high speed state, the band brake B / B is released and the low clutch Although the L / C is engaged, the one-way orifice 52 is provided in the hydraulic pressure supply circuit 50 of the low clutch L / C as shown in the schematic diagram of FIG. And the start of engagement of the low clutch L / C is performed gently.
A low clutch timing valve 22 is provided in a bypass passage 54 that bypasses the one-way orifice 52 in the one-way orifice 52.
The 50 can be communicated without passing through the one-way orifice 52.

That is, the low clutch timing valve 22 is ON, O
By supplying the pilot pressure supplied from the circuit 56 through the FF-driven low clutch solenoid valve 23 to the low clutch timing valve 22, the low clutch timing valve 22 is switched upward in the figure and the bypass passage 54 is In this state, the throttle function of the one-way orifice 52 is not exhibited, and it can be considered that the communication state, that is, the extremely small aperture amount is set.

On the other hand, when the pilot pressure is drained by the low clutch solenoid valve 23, the low clutch timing valve 22 is switched downward in the drawing to shut off the bypass passage 54, and the function of the one-way orifice 52 is exerted to restrict the throttle. The amount is set to be large.

In this embodiment, the low clutch solenoid valve is used.
23 is a low clutch timing valve that drains pilot pressure with an OFF signal and pilot pressure with an ON signal.
Actuated to supply

As described above, the one-way orifice 52, the low clutch timing valve 22, and the low clutch solenoid valve 23, which can change the throttle amount of the hydraulic pressure supply circuit 50, can be used.
Thereby, the variable aperture means 58 is configured.

Here, in the present embodiment, a throttle sensor 10 as an accelerator opening detecting means is provided in the control unit 10.
2 and a throttle opening signal and a vehicle speed signal detected by a vehicle speed sensor 104 serving as a vehicle speed detecting means, and determining a vehicle speed according to a shift schedule as shown in FIG. Shift determination means
106 and the 1-2 solenoid valves 13 and 2- shown in Table 2 based on the shift determination signal from the shift determination means 106.
3 solenoid valve 14 and 3-4 solenoid valve 15
Is provided with a shift control means 108 for outputting an ON / OFF signal.

Also, the control unit 10 receives a throttle opening signal from the throttle sensor 102 and calculates a change rate of the accelerator opening corresponding to the throttle opening. A change rate calculating means 110 is provided, and an opening change rate of the throttle opening change rate calculating means 110 is provided. A throttle amount judging means 112 for inputting a signal, a throttle (TH) signal from the throttle sensor 102 and a downshift signal detected by the shift judging means 106 and judging the amount of throttle of the variable throttle means 58 is provided. Have been.

Then, the magnitude of the diaphragm amount determined by the diaphragm amount determining unit 112 is output to the variable diaphragm control unit 114, and the variable clutch control unit 114 outputs the low clutch solenoid valve 2
A drive signal is output to the stop 3. The aperture amount determination means 112 and the variable aperture control means 114 constitute an aperture amount switching means 116.

Incidentally, the variable aperture means 58 is controlled by the aperture amount determination means 112.
In determining the aperture amount, a map as shown in FIG. 7 is used.
Has been entered.

That is, the map shows the vehicle speed in the horizontal direction and the throttle opening TH in the vertical direction, shows the limit value of the change rate at the corresponding point of these two points, and is detected by the throttle opening change rate calculating means 110. When the value exceeds the limit value, the timing at which the aperture amount of the variable aperture control unit 114 is set to be small is advanced.

FIG. 8 shows a flow of control performed by the control unit 10. The flow will be described below in order. Before the control based on this flow is executed, the aperture amount of the variable aperture means 58 is set to be large. State, that is,
An OFF signal is output to the low clutch solenoid valve 23, and the low clutch timing valve 22
Is set to shut off.

That is, in the flow chart reads the throttle opening TH ₁ in step I, T in step II, the Step I
After reading the H _1, counts the predetermined sample time Delta] t, read this Delta] t after the throttle opening degree TH ₂ again at step III.

In step IV, the vehicle speed V is read, and the optimum shift position is read from the shift schedule (shift point map) shown in FIG. 5 based on the throttle opening TH ₂ and the vehicle speed.
In the next step VI, it is determined whether or not downshifting is performed, and if "NO", the process returns to step I again.
Throttle opening TH ₁ and TH ₂ read in step I and step III proceeds to step VII in the case of "YES", the throttle opening change rate Is required.

The formula at this time is: Given by

In the next step VIII, based on the map shown in FIG. 7, a predetermined value at which the rate of change of the throttle opening is limited is read from the throttle opening TH and the vehicle speed V. Is determined to be large, and in the case of "YES", the process proceeds to step X, and an ON signal is output to the low clutch solenoid valve 23 for a predetermined time (until the low clutch L / C is completely engaged). On the other hand, while the throttle amount of the variable throttle means 58 is set small, in the case of “NO”, the process proceeds to Step XI, and outputs an OFF signal to the low clutch solenoid valve 23,
The aperture amount of the variable aperture means 58 is continuously set to a large value.

With the above configuration, in the transmission hydraulic pressure control device of the present embodiment, when the downshift from the fourth speed to the third speed is performed, after the band brake B / B is released, a new low clutch L / C
Is engaged, but the hydraulic pressure supply circuit 50 of the low clutch L / C
The variable throttle means 58 provided at the time point when the throttle amount is switched from large to small is determined by the throttle opening degree change rate calculating means 11.
Change rate of throttle opening calculated by 0 It is determined based on the

For this reason, when the driver tries to accelerate, the shifting hydraulic pressure supplied to the low clutch L / C is changed from the solid line with the large throttle amount to the broken line with the small throttle amount as shown in FIG. As described above, the hydraulic pressure characteristics are changed and the hydraulic pressure rise speed is increased, so that the engagement timing of the low clutch L / C can be advanced.

On the other hand, during the downshift, the engine rotation is lower than the rotation on the drive wheel side, so when the low clutch L / C is engaged in this state, the engine Power is input to the engine and the engine speed is increased.

Therefore, when the engagement timing of the low clutch L / C is advanced at the time of the above-described depression downshift, the rotation of the engine is accelerated by the input rotation on the drive wheel side, and
10 (a) As shown by the solid line in FIG. 10 (a), the rise of the engine speed is large (the broken line in the diagram is the conventional characteristic), and the time required to reach the target engine speed during downshifting is shortened. Can be greatly shortened, and remarkable improvement in acceleration performance can be achieved.

By the way, when the downshift is not caused by the depression described above but is a normal downshift, the rate of change of the throttle opening becomes equal to or less than a predetermined value.
Because the timing of setting the aperture value of 58 to small is delayed,
Although also small increase rate of the engine speed as shown in Figure 10 (b), the output torque T _o can be obtained as a few properties of rapid change component, it is possible to achieve a significant reduction of the shift shock.

In this embodiment, the downshift from the fourth speed to the third speed is described as an example. However, in the hydraulic pressure supply circuit disclosed in the present embodiment, the downshift from the third speed to the second speed is performed. In this case, the release pressure is removed from the band servo 17 when the band brake B / B is engaged, but the present invention can be applied when the release pressure is removed.

Further, in the present embodiment, when the throttle amount determining means 112 determines whether or not the rate of change of the throttle opening is equal to or more than a predetermined value, a preset map shown in FIG. 7 is used. By making judgments much easier,
Control can be performed more quickly and the electric circuit can be simplified.

Effect of the Invention As described above, in the transmission fluid pressure control device for an automatic transmission according to the present invention, the rate of change of the accelerator opening is detected, and the rate of change is determined according to the accelerator opening and the vehicle speed during a downshift. When the value exceeds the set predetermined value, the timing for switching the throttle amount of the variable throttle means provided in the hydraulic pressure supply circuit of the friction element to a small value is set earlier. Optimum control of the variable throttle means can be performed in consideration of the accelerator opening and the vehicle speed in addition to the rate of change of the throttle.

If the timing of reducing the throttle amount of the variable throttle means during the step-down downshift is advanced, the rotation of the power source is accelerated by the rotation input on the drive wheel side, and the rotation of the drive source is increased. Can rapidly reach the rotation speed corresponding to the gear ratio after the downshift, and can significantly reduce the shift lag during acceleration.

On the other hand, when the rate of change is smaller than a predetermined value set in accordance with the accelerator opening and the vehicle speed, the switching time point of the variable throttle means is set later, so that the control focusing on the reduction of shift shock is performed. Becomes possible.

Therefore, according to the present invention, at the time of downshifting, the timing for reducing the variable throttle amount in the entire accelerator opening range and the entire vehicle speed range is optimally controlled, and the shift lag and the shift are adjusted in accordance with the accelerator opening and vehicle speed at that time. Shock reduction can be optimally balanced.

According to the second aspect, the switching time of the variable throttle means is performed according to a map in which the accelerator opening and the vehicle speed input to the throttle amount switching means are used as dimensional axis elements.
This provides various excellent effects such as quick control and simplification of the circuit configuration of the aperture amount switching means.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the concept of the present invention, FIG. 2 is a schematic diagram showing one embodiment of the present invention, and FIG. 3 is a schematic diagram showing a power train of an automatic transmission to which the present invention is applied. Figure,
FIG. 4 is a schematic configuration diagram showing a hydraulic pressure control circuit of an automatic transmission to which the present invention is applied, FIG. 5 is an explanatory diagram showing one embodiment of a shift schedule used in the present invention, and FIG. FIG. 7 is a control map used in one embodiment of the present invention, FIG. 8 is a flowchart showing one processing example for executing control performed in the present invention, and FIG.
FIGS. 10 (a) and 10 (b) are characteristic diagrams of the engine and output torque when the control mode of the present invention is changed, and FIGS. FIG. 4 is an explanatory diagram showing a downshift state by a shift diagram. 22 ... Low clutch timing valve, 23 ... Low clutch solenoid valve, 50 ... Hydraulic pressure supply circuit, 52 ... One-way orifice, 54 ... Bypass passage, 58 ... Variable throttle means, 100 ... Control unit, 102: throttle sensor, 104: vehicle speed sensor, 106: shift determining means (downshift detecting means), 108: shift control means, 110
... Throttle opening degree change rate calculating means (accelerator change rate detecting means), 112 ... throttle amount determining means, 114 ... variable throttle control means, 116 ... throttle amount switching means, L / C ... low clutch (friction) Elements), A / T: automatic transmission, E: engine (power source).

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16H 61/00

Claims (2)

(57) [Claims] An automatic transmission, comprising a plurality of hydraulically operated friction elements, switching a transmission gear by engaging or releasing these friction elements, and appropriately shifting and outputting an input rotation from a power source. A variable throttle means provided in a hydraulic pressure supply circuit of a friction element that is fastened at the time of a downshift, and switching between a small throttle amount for normally supplying hydraulic pressure and a large throttle amount for slowly supplying hydraulic pressure; A downshift detecting means for detecting a downshift, an accelerator opening detecting means for detecting an accelerator opening, an accelerator change rate detecting means for detecting a change rate of the accelerator opening, a vehicle speed detecting means for detecting a vehicle speed, When the rate of change of the accelerator opening during a downshift is equal to or greater than a predetermined value set in accordance with the accelerator opening and the vehicle speed, the timing of switching the throttle amount of the variable throttle means to a small value is advanced. A weight switching means Ri, that the provided shift hydraulic pressure control device for an automatic transmission according to claim. 2. The throttle amount switching means inputs a limit value of an accelerator change rate for switching the variable throttle means by mapping in advance the accelerator opening and the vehicle speed as a dimensional axis element, and inputs the limit value along the map. 2. The apparatus according to claim 1, wherein said control means controls a throttle amount switching means.