JP2950311B2 - Hydraulic control device for automatic transmission for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engagement-side hydraulic friction engagement device that is frictionally engaged during downshifts among a plurality of hydraulic friction engagement devices that switch the speed of an automatic transmission for a vehicle. The present invention relates to a hydraulic control apparatus for an automatic transmission for a vehicle in which a flow rate of supplied hydraulic oil is changed by switching control of an orifice.

[0002]

2. Description of the Related Art An automatic transmission for a vehicle, in which an engaging hydraulic friction engagement device is engaged for downshifting from a predetermined gear to a lower gear, is used during power-on traveling. In order to smoothly perform the downshift, the engagement start timing of the engagement-side hydraulic friction engagement device, the turbine rotation speed, that is, the input shaft rotation speed of the vehicle automatic transmission, and the vehicle automatic transmission It is desired that the timing when the ratio with the output shaft rotation speed becomes equal to the gear ratio after the speed change of the vehicle automatic transmission, that is, the rotation speed synchronization timing substantially coincides.
To match these timings, for example, see
An orifice switching device disclosed in Japanese Patent No. 296063 is provided in a hydraulic circuit, and a downshift from a predetermined gear to a lower gear is performed while the vehicle is powered on at a predetermined vehicle speed or higher. In this case, the flow rate of the hydraulic oil supplied to the engagement-side hydraulic friction engagement device is reduced by using a small orifice from the downshift command to immediately before the engagement of the engagement-side hydraulic friction engagement device. Then, by increasing the flow rate through a large orifice having a smaller flow resistance than that of the small orifice, the engagement start timing of the engagement side hydraulic friction engagement device is controlled so that the power can be controlled regardless of the engine load state. It is conceivable to make the on-down shift smooth.

In a power-off downshift or coast-down shift during coasting of a vehicle, the output torque of the engine is negative and the input shaft of the automatic transmission, that is, the Durbin rotation speed, cannot be increased by the engine output torque. It is necessary to gradually pull up by the rotational force from the drive wheels using the operation area of the accumulator connected to the engagement-side hydraulic friction engagement device.

[0004]

However, as described above, in the period from the downshift command to immediately before the engagement of the engagement-side frictional engagement device, the operating oil supplied to the engagement-side frictional engagement device is reduced. If the hydraulic oil whose flow rate has increased through the large orifice is supplied to the engagement side hydraulic friction engagement device after the supply is suppressed by the small orifice, the capacity of the accumulator is insufficient and the operating area of the accumulator is early. In some cases, the shift is completed due to the sudden increase in the engagement pressure of the engagement-side hydraulic friction engagement device, and the shift shock becomes remarkable.

When the line pressure regulated in relation to the throttle opening is used as the base pressure of the engagement pressure of the engagement-side hydraulic friction engagement device, the internal pressure of the engagement-side hydraulic friction engagement device is reduced. The shift response is not obtained because much time is required for filling the hydraulic oil. For this reason, in a coast downshift requiring an engine brake, for example, when the shift lever is operated to the engine brake range, a quick shift response may not be obtained in some cases.

On the other hand, the flow resistance of the large orifice, through which the hydraulic oil supplied to the engagement-side hydraulic friction engagement device passes, is increased, or the large orifice is connected to the engagement-side hydraulic friction engagement device. It is conceivable to further increase the capacity of the accumulator. However, when the flow resistance of the large orifice is increased, no matter how fast the switching to the large orifice is performed during power-on downshifting at low vehicle speed and low load, the input shaft rotation speed of the automatic transmission, that is, the turbine rotation speed is synchronized. At this point, the engagement start point of the engagement-side hydraulic friction engagement device cannot be made in time, so that the turbine rotation speed increases and the shift feeling decreases. In addition, when the capacity of the accumulator is increased, there is a problem that the size of the automatic transmission becomes large and the mountability is reduced, and the fuel consumption is reduced in accordance with the increase in the weight.

The present invention has been made in view of the above circumstances, and an object thereof is to change a large orifice and an accumulator related to supply of hydraulic oil to an engagement-side hydraulic friction engagement device. It is another object of the present invention to provide a hydraulic control device for an automatic transmission for a vehicle, in which a shift shock due to an insufficient capacity of an accumulator in a coast downshift is suppressed and a shift response of the coastdown shift is obtained.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the gist of the present invention is to provide a plurality of hydraulic friction engagement devices for switching a gear position of an automatic transmission for a vehicle. In the hydraulic friction engagement device, the flow rate of the hydraulic oil supplied to the engagement-side hydraulic friction engagement device that is frictionally engaged for the downshift of the vehicle automatic transmission is changed by switching the orifice during the downshift. A hydraulic control device for a vehicle automatic transmission of a type to be changed, comprising: (a) a coast-down shift determining means for determining whether a coast-down shift command is output during coasting of the vehicle; ) from its being determined and the command of downshifting during coasting of the vehicle is output by the coast downshift determining means
Until the orifice switching period determined as a period up to any point in time until the start of the downshift, the orifice of the oil passage that supplies the operating oil to the engagement side hydraulic friction engagement device passes through the orifice of the flow resistance. A hydraulic oil flow rate changing means for switching to a small large orifice, but for switching the orifice of the oil passage from the large orifice to a small orifice having a larger flow resistance when the orifice switching period elapses.

[0009]

In this manner, the period from the time when the command for coast downshift during coasting traveling is output by the hydraulic oil flow rate changing means to the time when the downshift starts is determined. Until the orifice switching period elapses, the orifice of the oil passage that supplies hydraulic oil to the engagement side hydraulic friction engagement device is switched to a large orifice having a small flow resistance. The orifice of the path is switched from a large orifice to a small orifice with a greater flow resistance. For this reason, after the coast downshift command, the supply of hydraulic oil to the engagement-side hydraulic friction engagement device is promoted to make the engagement timing earlier, and after the orifice switching period elapses, the hydraulic oil is supplied through the small orifice. The accumulator is supplied to the engagement-side hydraulic friction engagement device and the accumulator connected thereto, and the accumulator operation period of the accumulator is extended to reduce the increase in the engagement pressure. The rapid rise of the engagement pressure and the shift shock are suitably eliminated, and the shift responsiveness of the coast downshift is suitably improved, so that the engine brake can be obtained quickly. That is, without changing the large orifice or accumulator related to the supply of hydraulic oil to the engagement-side hydraulic friction engagement device, the shift shock due to the insufficient capacity of the accumulator in the coast downshift is suppressed, and the coast downshift is performed. Shift responsiveness is obtained.

[0010]

Preferably, when the coast-down shift determining means determines that a coast-down shift command is output during coasting of the vehicle, the hydraulic friction engagement device is activated. The line pressure, which is the line pressure, is increased to a predetermined value. , Are further provided. With this configuration, the line pressure is increased during the period from the coast down shift command to the start of the shift or before the shift, so that the return spring of the engagement-side hydraulic friction engagement device is elastically deformed. As a result, the return spring section until the friction of the friction material starts is further shortened, so that the shift response of the coast downshift is further enhanced, and the engine brake can be obtained quickly.

Preferably, the vehicle further includes coast downshift end determining means for determining whether or not the coast downshift is completed, and the hydraulic oil flow rate changing means terminates the downshift by the downshift end determining means. If it is determined that the operation has been performed, the orifice of the oil passage for supplying hydraulic oil to the engagement-side hydraulic friction engagement device is switched from the small orifice to the large orifice. This eliminates the need to switch from the large orifice to the small orifice at the time of the coast down shift command.
Even if foreign matter is clogged in the small orifice, there is an advantage that downshifting can be achieved by supplying hydraulic oil to the engagement side hydraulic friction engagement device through the large orifice instead.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a torque converter 12 connected to a vehicle engine 10, an automatic transmission 14, a differential gear device 16, and a hydraulic control device or a hydraulic control circuit 18 for controlling the speed of the automatic transmission 14. , Its hydraulic control circuit 1
The electronic control unit 20 for shifting the vehicle 8 and the like are shown. Power output from the engine 10 is transmitted to drive wheels (not shown) via the torque converter 12, the automatic transmission 14, the differential gear device 16, the left and right axles 22 and 24, and the like.

The torque converter 12 includes a pump impeller 28 connected to a crankshaft 26 of the engine 10.
And a turbine wheel 32 connected to the input shaft 30 of the automatic transmission 14 and to which power is transmitted from a pump wheel 28 via a fluid, and which is fixed to a fixed position housing 36 via a one-way clutch 34. And a lock-up clutch 40 that directly connects the pump impeller 28 and the turbine impeller 32 via a damper (not shown).

The automatic transmission 14 has four forward speeds and one reverse speed.
A high speed gear stage, wherein the input shaft 30, a set of Ravigneaux type planetary gear units 44, a ring gear 48 which rotates together with a ring gear 46 of the Ravigneaux type planetary gear units 44, An output shaft, that is, a counter shaft 50 for transmitting power to and from the dynamic gear device 16 is provided.

In the Ravigneaux type planetary gear set 44, one set of single pinion planetary gear sets 52 and one set of double pinion planetary gear sets 54 share a carrier 56 and the ring gear 46. The single pinion planetary gear device 52 includes a sun gear 58, a planetary gear 60 attached to the carrier 56, and the ring gear 46. The double pinion planetary gear 54 includes a sun gear 62 and a first pinion gear 64 and a second pinion gear 66 rotatably attached to the carrier 56.

The components of the single pinion planetary gear set 52 and the double pinion planetary gear set 54 are not only integrally connected to each other but also selectively connected to each other by three clutches C1, C2 and C3. Have been. In addition, the single pinion planetary gear set 5
2 and some of the components of the double pinion planetary gear set 54 are selectively connected to the housing 36 by three brakes B1, B2, and B3, and further, some of those components are in two one-way directions. Clutch F1, F2
The housing 36 is engaged with the housing 36 depending on its rotation direction. Note that parts other than the counter shaft 50 of the torque converter 12 and the automatic transmission 14 are:
Since it is configured symmetrically with respect to the axis of the input shaft 30 and the like, the lower side of the axis is omitted in FIG.

The clutch C is a hydraulic friction engagement device.
1, C2, C3 and brakes B1, B2, B3 are constituted by, for example, a multi-plate clutch or a band brake provided with one or two bands having opposite winding directions, and the like, and the electronic control unit for shifting is provided. The frictional engagement and the disengagement thereof are controlled by the hydraulic control circuit 18 which operates in accordance with the command from the control unit 20, respectively, so that the gear ratio γ (= the input shaft 30) as shown in the engagement table of FIG. Thus, four forward speed stages and one reverse speed stage having different rotation speeds / rotation speeds of the counter shaft 50 are obtained. In FIG. 2, "1ST",
“2ND”, “3RD”, and “4TH” represent the first gear, second gear, third gear, and fourth gear on the forward side, respectively. It decreases gradually from the first gear to the fourth gear. As can be seen from FIG. 2, the 4-3 downshift from the fourth gear to the third gear is performed by releasing the disengaged hydraulic friction engagement device (brake B1) and engaging the hydraulic pressure. This is a so-called clutch-to-clutch shift executed by engaging the frictional engagement device (clutch C1) during the shift period.

The hydraulic control circuit 18 includes four solenoid valves SV1 to SV4 used for controlling the gear position of the automatic transmission 14, etc., and a throttle opening sensor 76 described later.
A linear solenoid valve SLT that generates a control oil pressure P _S having a magnitude corresponding to the throttle opening TA detected by the
For example, a linear solenoid valve _SLN that generates a control oil pressure P _SLN used as an accumulator back pressure described later, a frictional engagement of the lock-up clutch 40, a release of the frictional engagement, and a hydraulic pressure for controlling the slip amount and the like. It is provided with a linear solenoid valve SLU and the like which are generated.

The shift electronic control unit 20 includes a CPU 7
0, a RAM 72, a ROM 74, and a so-called microcomputer including an input / output interface (not shown). The CPU 70 processes an input signal in accordance with a program stored in the ROM 74 in advance while using the storage function of the RAM 72, and The provided solenoid valves SV1 to SV4 and the linear solenoid valves SLT, SL
N, SLU, etc. are controlled.

The shift electronic control unit 20 includes a throttle opening sensor 76 for detecting an opening TA of a throttle valve provided in an intake pipe (not shown) of the engine 10.
An engine rotation sensor 78 for detecting the rotation speed of the engine 10, and an input shaft rotation sensor 8 for detecting the rotation speed of the input shaft 30, that is, the turbine rotation speed _NT (rpm).
0, rotation speed of the counter shaft 50 (output shaft rotation speed)
N _o That vehicle speed sensor 82 for detecting the vehicle speed V, the operating position i.e. L of the shift lever 84, S, D, N, R, P
From the operation position sensor 86 that detects any of the ranges,
A signal indicating the throttle opening TA, the engine speed _NE
Signal representative of the signal representative of the input shaft rotational speed N _IN, output shaft speed N _o i.e. signals representing the vehicle speed V, the signal representing the shift lever operation position P _ST are supplied.

FIGS. 3 and 4 show the hydraulic control circuit 18.
Are shown. FIG. 3 shows a pressure regulating valve 90 for regulating a line oil pressure P _L which is a source pressure of hydraulic oil supplied to the clutch C1 and the brake B1 and the like, the linear solenoid valve SLT, and a constant pressure of the line oil pressure P _L. P _SOL
The pressure reducing valve 92 supplies the constant pressure P _SOL to the linear solenoid valve SLT, a pump 94 which is a source of hydraulic pressure of hydraulic oil, and a strainer 124.

The pressure reducing valve 92 includes a spool valve 96 for opening and closing between an input port a and an output port b, and a spring 98 for urging the spool valve 96 in a valve opening direction. The line hydraulic pressure P supplied to a
_L is reduced to the constant pressure P _SOL and generated at its output port b. The input port c of the pressure reducing valve 92 is supplied with the hydraulic pressure of the output port b as a feedback hydraulic pressure. The constant pressure P _SOL is controlled by the spool valve 96.
If the pressure receiving area which communicates with the input port c A _{MO D,} the urging force of the spring 98 and W _MOD, a constant pressure is expressed by the following equation.

[0024]

[ _Equation 1] P _SOL = W _MOD / A _MOD (1)

The linear solenoid valve SLT includes a spool valve 100 for opening and closing between an input port a and an output port b thereof, and a spring 102 for urging the spool valve 100 in a valve opening direction. . The constant pressure P _SOL is supplied to the input port a, and the constant pressure P _SOL is supplied to the input port a.
_SOL is the control pressure P _S as a hydraulic pressure regulated in response to the exciting current of the linear solenoid S _SLT is generated at the output port b. The urging force for urging the spool valve 100 in the valve closing direction of the output port b in accordance with the exciting current of the linear solenoid S _SLT is F _I , the urging force of the spring 102 is W _SLT , Assuming that the area of the annular pressure receiving surface of the land 104 is A _SLT , the control oil pressure P _S is expressed by the following equation. The land 1
Since the space 108 between the land 04 and the land 106 and the output port b are communicated by the communication hole 110, the hydraulic pressure acting on the annular pressure receiving surface is equal to the control hydraulic pressure P.
_Has become _S.

[0026]

P _S = F _I / A _SLT −W _SLT / A _SLT (2)

The pressure regulating valve 90 has an input port b and an output port b.
A spool valve 112 that opens and closes between the
The pool valve 112 is attached via the engagement plate 114 in the valve closing direction.
And an input port thereof.
Hydraulic pressure of the working oil supplied from the pump 94 to the
Is controlled by the control hydraulic pressure P supplied to the input port a._STo
Corresponding to the line pressure P_LAdjust the pressure. Above pressure regulating valve
90 input port c is supplied with the hydraulic pressure of the input port b.
It is supplied as feedback hydraulic pressure. The above spring
The urging force of_REGOf the spool valve 112
Let the area of the annular pressure receiving surface of the land 118 be A_REG1, The above sp
To bias the valve element 112 in the valve closing direction of the output port d.
The area of the pressure receiving surface of the biasing member 122 is A_REG2Then,
In hydraulic pressure P _LIs represented by the following equation.

[0028]

P _L = (A _REG2 / A _REG1 ) · P _S + W _REG / A _REG1 (3)

Equation (3) indicates that the line oil pressure P _L is generated in proportion to the control oil pressure P _S. If the line pressure P _L (3) becomes larger than the hydraulic pressure calculated by the equation, the hydraulic oil in the strainer 124 from the output port d of the pressure regulating valve 90 is returned.

FIG. 4 shows a part of the hydraulic control circuit 18 for switching the automatic transmission 14 between the fourth speed and the third speed. FIG. 4 shows the solenoid valves SV1 and SV2 having a normally closed structure.
3-4 shift valve 150, shift timing valve 152, orifice switching valve 154, orifice 156, orifice 158 having an inner diameter smaller than that of orifice 156,
A clutch accumulator 160, a brake accumulator 162, an orifice 164 before the accumulator, and the like are shown.

The solenoid valve SV1 has an orifice 1
Port a to which the constant pressure P _SOL is supplied through port 68
And a drain port b, the port a of which is connected to the input port a of the 3-4 shift valve 150. The solenoid valve SV1 shuts off the flow of hydraulic oil between the two ports in the non-excited state of the OFF state, i.e. the solenoid S _SV1, the excited state of the ON state, namely the solenoid S _SV1 supplied to the port a By releasing hydraulic oil to the atmospheric pressure from the drain port b, the 3-4 shift valve 1 connected to the port a is released.
The hydraulic pressure of the 50 input ports a is switched between the constant pressure P _SOL and the atmospheric pressure.

The solenoid valve SV2 has an orifice 1
Port a to which the constant pressure P _SOL is supplied through
And a drain port b, the port a of which is connected to the input port a of the orifice switching valve 154. The solenoid valve SV2 blocks the flow of hydraulic fluid between the two ports in the non-excited state of the OFF state, i.e. the solenoid S _SV2, in the excited state of the ON state, namely the solenoid S _SV2 supplied to the port a By releasing the hydraulic oil to the atmospheric pressure from the drain port b, the oil pressure at the input port a of the orifice switching valve 154 connected to the port a is switched between the constant pressure P _SOL and the atmospheric pressure.

The 3-4 shift valve 150 includes input ports a, b, and c, input / output ports d and e, an output port f, a drain port g, and the input / output port d. A spool valve element 172 for selectively communicating with one of the drain ports g and selectively communicating the input / output port e with one of the input ports c and output ports f; A spring 174 for urging the valve 172 in a direction in which the input / output port d communicates with the drain port g and the input / output port e communicates with the input port c.
And The input port a is connected to the port a of the solenoid valve SV1 as described above, and the line pressure P _L is supplied to the input ports b and c through an oil passage 176. The input / output port d is connected to the brake B1 through an oil passage 177.

The area A _V1a of the end face of the land 178 communicating with the biasing force W _{V1 of the} spring 174 and the input port a of the spool valve 172 is A _V1a · P _SOL >
W _V1 . Therefore, when the solenoid valve SV1 is in the OFF state, the operating oil of the constant pressure P _SOL is supplied to the input port a.
The spool valve 172 communicates with the input port b and the input / output port d as shown on the left side of FIG. 4 against the urging force W _V1 of the spring 174, and communicates with the input / output port e and the output port f. When the solenoid valve SV1 is in the ON state, the hydraulic pressure of the input port a is set to the atmospheric pressure, and the spool valve 172 is moved by the urging force W _{V1 of the} spring 174. As shown on the right side of FIG.
And the input / output port e communicates with the input / output port d and the drain port g.

The shift timing valve 152 includes input ports a, b, and c, a drain port d, a spool valve element 180 for opening and closing between the input port b and the drain port d, and a spool valve element 180. And a spring 182 for urging the valve in the valve opening direction. The input ports a and c are connected to the oil passage 183 and the oil passage 1 respectively.
85, it is connected to the brake B1 and the output port f of the 3-4 shift valve 150. The control port PSLN generated by the linear solenoid valve _SLN is supplied to the input port b.

The above control oil pressure P_SLNIs the spool valve
180, a ring of a land 184 communicating with the input port a.
The area of the pressure receiving surface_V2aOf the spool valve element 180
Annular pressure reception of the land 186 communicating with the input port b
A is the area of the surface_V2b, The urging force of the spring 182 is W
_V2Then A_V2a・ P_L> A_V2b・ P_SLN+ W_V2Tona
It is so. Therefore, the solenoid valve S
When V1 is OFF, the line is connected to the input port a.
Hydraulic pressure P_LIs supplied, the spool valve element
180 is the urging force W of the spring 182_V2Figure against
4, the input port c and the drain
The import d moves in the direction in which it communicates. On the other hand,
When the solenoid valve SV1 is ON, the input port a
Since the oil pressure is the atmospheric pressure, the spool valve element 180 is
The urging force W of the spring 182 _V24 on the left side of FIG.
As shown in FIG.
D moves in a direction that does not allow communication.

The orifice switching valve 154 includes input ports a, b and c, an output port d communicating with the input port b, a spool valve 188 for opening and closing the input port c and the output port d, The spool valve 18
And a spring 190 for urging the valve 8 in the valve opening direction. The input port a is connected to the port a of the solenoid valve SV2 as described above, and the input port b is connected to the input / output port e of the 3-4 shift valve 150 via an oil passage 192. The orifice 156 is provided in the middle of the oil passage 192, and the orifice 158 is provided at a position closer to the orifice switching valve 154 than the orifice 156. The above input port c
Is connected to a portion of the oil passage 192 between the orifice 156 and the orifice 158. The port d is connected to the clutch C1 by an oil passage 194.

The constant pressure P _SOL is controlled by the spool valve 1
The area of the pressure receiving surface of the land 195 communicating with the input port a of A 88 is A _V3a , and the _urging force of the spring 190 is W
Assuming that _V3 , A _V3a · P _SOL > W _V3 . When the solenoid valve SV2 is turned off, the constant pressure P _SOL is supplied to the port a of the orifice switching valve 154, so that the port c of the orifice switching valve 154 as shown on the left side of FIG. Is Land 1
Blocked by 95. As a result, when hydraulic oil is supplied to the clutch C1 through the oil passages 192 and 194, the supplied hydraulic oil is supplied to the two orifices 1
56 and 158 will be passed in series. This state where the flow resistance is large is called a small orifice. On the other hand, when the solenoid valve SV2 is turned on, the oil pressure at the port a of the orifice switching valve 154 is set to the atmospheric pressure.
As shown on the right side of FIG. 4, the port c and the port d of the orifice switching valve 154 are connected. as a result,
The clutch C1 passes through the oil passage 192 and the oil passage 194.
When the hydraulic oil is supplied to the orifice 1, the supplied hydraulic oil has a larger inner diameter than the orifice 158.
56 will pass mainly. This state where the flow resistance is small is called a large orifice. Switching control between the small orifice state and the large orifice state is referred to as orifice switching control.

The portion of the oil passage 192 closer to the input / output port e of the 3-4 shift valve 150 than the orifice 156 and the oil passage 194 are connected by an oil passage 196. The oil passage 196 is provided with a one-way valve 198 that permits the flow of hydraulic oil from the oil passage 194 to the oil passage 192, but prohibits the flow in the opposite direction. The one-way valve 198 allows the oil passage 1
The supply of hydraulic oil to the clutch C1 through 96 is prohibited.

The clutch accumulator 160 is
A housing 200, a port a and an input port b provided in the housing 200,
The piston includes a stepped cylindrical piston 202 slidably accommodated in the cylinder 0 and a spring 204 for urging the piston 202 toward the port a. The piston 202 includes a large diameter portion 206 and a small diameter portion 208, and an end surface 210 of the large diameter portion 206 opposite to the small diameter portion 208 is communicated with the port a. Further, an annular end face 212 formed at the boundary between the large diameter portion 206 and the small diameter portion 208 is communicated with the input port b. The port a is connected to the oil path 194 by an oil path 214, and the line pressure P _L is supplied to the input port b as an accumulator back pressure.

When the solenoid valve SV1 is in the OFF state and the hydraulic pressure at the port a of the clutch accumulator 160 is atmospheric pressure, the piston 202 is actuated by the urging force of the spring 204 as shown on the right side of FIG. It moves toward the port a of the accumulator 160, and the amount of hydraulic oil stored inside the clutch accumulator 160 is minimized. On the other hand, if the solenoid valve SV1 is turned on and the line hydraulic pressure P _L is supplied to the port a and the input port b of the clutch accumulator 160, the piston 202 corresponds to the magnitude of the line pressure P _L. The inside of the housing 200 is moved by the determined moving distance. The difference (A _A1a -A _A1b ) between the area A _A1a of the end face 210 of the piston 202 and the area A _A1b of the annular end face 212 is determined by the area difference ΔA _A1 and the spring 2 at the moving distance x of the annular piston 202.
Assuming that the _urging force by 04 is W _A1 (x), the relationship represented by the following equation (4) is established.

The urging force W _A1 (x) of the spring 204
Is expressed by the following equation (5), where the urging force of the spring 204 when the moving distance x is zero is W _A1 (0) = W _A10 , and the spring constant of the spring 204 is k ₁ . Also,
(4) If subtractive and (5) the urging force W _A1 (x) from the equation, relation between the line pressure P _L and the moving distance x (6) is obtained.

P _L = W _A1 (x) / ΔA _A1 (4) W _A1 (x) = W _A10 + k ₁ · x (5) x = (ΔA _A1 / k ₁ ) · P _L − (W _A10 / k ₁ ) (6)

If the right side of the equation (6) does not become larger than zero, that is, if the line oil pressure P _L does not become larger than a predetermined threshold oil pressure P _LA1TH = W _A10 / ΔA _A1 , the accumulator 160 operates. Do not start containing oil. This threshold oil pressure P _{LA1T H} is slightly higher than the line oil pressure P _L at the time when the frictional engagement of the clutch C1 is started. Therefore, the clutch accumulator 160 starts storing the hydraulic oil immediately after the clutch C1 starts the frictional engagement. If the line pressure P _L is increased beyond the threshold pressure P _LA1TH,
The clutch accumulator 160 continues to contain hydraulic oil up to its maximum capacity. Therefore, the amount of hydraulic oil supplied to the clutch C1 is reduced as compared with the case where the accumulator 160 does not store hydraulic oil, and the clutch C1
Of the engagement pressure P _C1 is moderated, and the frictional engagement is performed smoothly. This is the pressure increase mitigation operation of the accumulator 160, and is called an accumulating operation region.

When the line pressure P _L is increased, for example, the accumulator 160 is operated while the engagement pressure P _{C1 of the} clutch _C1 is high, but the line pressure P _L is reduced. When the engagement pressure PC1 of the clutch _C1 is low, the accumulator 1
60 accumulation operations are performed.

The brake accumulator 162 includes:
The port a is similar to the clutch accumulator 160, and the port a is connected to the oil passage 17 by an oil passage 216.
7 and the line oil pressure P _L is supplied to the input port b. This brake accumulator 162
Operates in the same manner as the clutch accumulator 160 when the brake B1 is frictionally engaged.

The pre-accumulator orifice 164, which functions as a hydraulic oil outflow rate limiting device, is
Orifice 218 provided in the orifice 2
And a brake accumulator 162 provided in the bypass passage 220 from the oil passage 177 side.
A one-way valve 222 that allows hydraulic fluid to flow to the side, but inhibits the flow in the opposite direction. Therefore, the orifice 164 before the accumulator does not suppress the flow rate of the hydraulic oil accommodated in the accumulator for brake 162 from the oil passage 177 through the oil passage 216, but the orifice 164 passes from the brake accumulator 162 through the oil passage 216. The flow rate of the working oil toward the oil passage 177 is suppressed. As a result, when the hydraulic pressure P _{B1 of the} brake B1 is reduced to the atmospheric pressure, the outflow of hydraulic oil from the brake B1 through the oil passage 177 can be hastened, so that the frictional engagement of the brake B1 is further released. It can be done quickly.

The clutch C1 of the present embodiment is, for example, as shown in FIG.
A multi-plate type as shown in FIG. In FIG. 5, a clutch C1 of the present embodiment includes an annular cylinder portion 230 formed integrally with the input shaft 30, and an annular piston 232 housed in the cylinder portion 230 so as to be slidable in the axial direction. A return spring 236 for urging the annular piston 232 in a direction in which the volume of an annular hydraulic chamber 234 formed by the cylinder portion 230 and the annular piston 232 decreases, and a plurality of friction plates 238 rotating together with the input shaft 30. A plurality of friction members provided at the other end of the intermediate shaft 240 provided at one end thereof with the sun gear 62 of the double pinion planetary gear device 54 so as to alternately overlap the friction plate 238, and rotating together with the intermediate shaft 240. And a plate 242.

When the hydraulic pressure of the hydraulic oil in the hydraulic chamber 234 is atmospheric pressure, the annular piston 232 is moved to the initial position shown in FIG. The distance from the friction plate 238 is D. From this state, the oil passage 19 provided inside the input shaft 30
When the line oil pressure P _L is supplied into the oil pressure chamber 234 through the pressure plate 4, the annular piston 232 is opposed to the friction plate 2 against the urging force of the return spring 236.
38. When the moving distance reaches the distance D, the annular piston 232 is moved.
The friction plate 238 and the friction plate 238 start engaging, and the friction plate 238 and the friction plate 242 start frictionally engaging, so that the clutch C1 starts frictional engagement.

The period until the moving distance of the annular piston 232 reaches the distance D is a period during which the return spring 236 continues elastic contraction until the friction plate 238 and the friction plate 242 are in close contact with each other. This period is referred to as a return spring period. The frictional engagement of the clutch C1 is performed more strongly as the hydraulic pressure of the working oil supplied through the oil passage 194 is higher.
Further, when the increasing rate of the hydraulic pressure of the working oil supplied through the oil passage 194 is large, the frictional engagement is performed more rapidly than when the increasing rate is small. In this embodiment, the brake B1, the clutch C2, and the like have the same configuration as the clutch C1.

FIG. 6 is a functional block diagram for explaining main control functions of the electronic control unit 20 for shifting. The shift control means 300 determines a shift based on the actual vehicle speed V and the throttle opening TA from a shift diagram stored in advance, outputs a shift command for realizing the determined shift speed, and outputs a plurality of shift commands. The gear position of the automatic transmission 14 is switched by selectively operating the hydraulic friction engagement device. For example, when it is determined that a 4 → 3 downshift has been performed, a shift command for releasing the brake B1 and engaging the clutch C1 is output to the 3-4 shift valve 150. 4 → 3 when the coast down shift, since the engine output torque T _E is negative, the engine rotational speed N _E be the brake B1 is released is not increased, the engine rotational speed N _E by the engagement of the clutch C1 Is raised. That is, the coast 4 → 3 due to the start of the engagement of the clutch C1.
The downshift is substantially started.

The coast-down shift determining means 302 determines whether or not the shift control means 300 outputs a clutch-to-clutch downshift command, for example, a 4 → 3 coast downshift command during coasting. The coast downshift includes not only a downshift that is automatically generated when the vehicle speed V decreases during coasting, but also an OD / OFF button that is operated during coasting in order to increase the engine braking force. And downshifts related to manual operation, which are generated when the shift lever 84 is operated from the drive range (D range) to the engine brake range (L, S range).

The orifice switching period determining means 304 obtains a hydraulic oil temperature T _OIL when a coast down shift command of the clutch-to-clutch, for example, a 4 → 3 coast down shift command is output, and obtains the hydraulic oil temperature T _OIL from a relationship stored in advance. Based on the temperature T _OIL , the orifice switching period T1, that is, the period from the coast down shift command to any point in time from the start of the shift is determined. Coast downshift completion determination means 306, 4 → 3 whether the coast downshift has ended, for example, and the turbine speed N _T and the output shaft rotation speed N _o × gear ratio γ is based on whether a match judge.

The orifice switching period T1 from the time when the coast-down shift determining means 302 determines that the coast-down shift command has been output during coasting of the vehicle to the time immediately before the start of the actual shift is determined. Until the passage, the port c and the port d of the orifice switching valve 154 are communicated with each other, so that the orifice of the oil passage 192 for supplying the operating oil to the engagement side hydraulic friction engagement device, that is, the clutch C1, has a large orifice with a small flow resistance. , The start of engagement of the clutch C1 is accelerated. However, when the orifice switching period T1 has elapsed, the orifice of the oil passage 192 is communicated with the port b and the port d of the orifice switching valve 154, so that the orifice is shifted from the large orifice. Switch to a small orifice with high flow resistance. When the orifice state is switched to a small orifice, the accumulator 160
Since the flow rate of the working oil supplied to the accumulator 160 is limited, the accumulating operation period of the accumulator 160 is extended, and the end of the coast downshift can be set within the accumulating operation period.

Therefore, in order to ensure that the coast downshift is completed within the accumulating operation period, the orifice state becomes small when the accumulator 160 starts operating, that is, when the frictional engagement of the clutch C1 starts. Since it is preferable that the orifice is in the orifice state, the orifice switching period T1 determined by the orifice switching period determining means 304 is preferably from when the coast down shift command is output until the shift is started. (The start of the coast downshift indicates any time between immediately before and immediately after the engagement of the clutch C1.)
The time from the output of the coast downshift command to the start of engagement of the clutch C1, that is, the time until the stroke D of the annular piston 232 disappears is determined by the line pressure P _L and the viscosity ρ of the hydraulic oil. In this case, since the throttle opening TA is zero, it is determined by the viscosity ρ of the hydraulic oil. Since the viscosity of the hydraulic oil ρ depends on the hydraulic oil temperature T _OIL, hydraulic fluid temperature T _OIL is higher the hydraulic oil viscosity ρ is low, the viscosity of the hydraulic oil ρ increases the low hydraulic fluid temperature T _OIL, Orifice switching period determination means 3
04, the lower the hydraulic oil temperature T _OIL is, the longer the orifice switching period T1 becomes, and the higher the hydraulic oil temperature T _OIL becomes.
_The higher the _{OIL, the} shorter the orifice switching period T1. FIG. 7 shows a data map corresponding to the relationship stored in advance. Incidentally, in the line pressure changing means 312 to be described later, when the line pressure P _L from the time of coast downshift command is changed, the determination of orifice switching period T1, the modified line pressure P _L
May be used, and a fixed value determined experimentally in advance may be used.

The hydraulic oil flow rate changing means 308 includes:
When the coast downshift determination unit 306 determines that the coast downshift has been completed, the orifice of the oil passage 192 that supplies hydraulic oil to the clutch C1 is switched from the small orifice to the large orifice.
The hydraulic oil flow rate changing means 308 may be switched from the small orifice to the large orifice immediately after the end of the coast downshift, but preferably, the small orifice is changed after a lapse of a preset allowance period T3 from the end of the coast downshift. To large orifice.

The line pressure rise period determining means 310 sets a line pressure rise value set in advance to enhance the shift response of the coast down shift to a line pressure P _L within a normal shift period.
That is, the line pressure increasing period T2 in which the pressure is adjusted from the value adjusted in accordance with the throttle opening TA so that the hydraulic friction engagement device in the automatic transmission 14 does not slip is generated by the annular piston 232 of the clutch C1 and the line pressure increasing period T2. The friction plate 23
8 when the distance D to the friction plate 2
38 and 242 are determined to be at or before the time when they contact each other. The line pressure rising period T2 is for improving the responsiveness by reducing the stroke D of the annular piston 232 of the clutch C1 so as not to start the operation of the accumulator 160. preferably, from the coast downshift command is outputted as the friction plate 238 and 242 than the period until the close contact with each other, the line pressure P _L is lowered from its raised value P1 to the value P2 during a gear change period It is set to be shorter by the time.

[0058] line pressure changing means 312, the coast-down shift command the increase value only the line pressure P _L is the line pressure rising period T2 determined by the line pressure rising period determining means 310 after it is determined that the output P1 until increase but to return the line pressure P _L when the line pressure rising period T2 has elapsed value P2 during a gear change period. The increase value P1 is experimentally set in advance so that the stroke D of the annular piston 232 is quickly reduced in the 4 → 3 coast downshift to increase the shift response.
The value P2 during the shift period is one factor that determines the flow rate of the hydraulic oil supplied to the engagement-side hydraulic friction engagement device that is engaged during the coast down shift, and is based on the engine torque. This is the value to be adjusted.

FIG. 8 shows a main part of the control operation of the shift electronic control device 20, that is, the speed of the automatic transmission 14 changes from the fourth gear to the third gear during coasting without the accelerator pedal being operated. It is a flowchart showing a part of a main routine showing a process executed when a command for a coast downshift, ie, a power off downshift, in which a downshift is performed to a gear, is determined.

In FIG. 8, at a step (not shown) corresponding to the coast downshift determining means 302,
→ If the determination of the output of the 3 coast downshift command is denied, the next control, for example, a power-on downshift routine is executed. If the determination is affirmed, SA1 and subsequent steps are started. Time point t ₁ in FIG. 9 shows this state. At this point, the gear is still in the fourth gear, and as shown in FIG. 2, the brake B1 is in the state of frictional engagement, and the clutch C1 is in the state of frictional engagement release. Has become.

At SA1, the timers t _a and t _b are initialized by clearing the contents of the timers to “0”, and thereafter, the vehicle speed V, the throttle opening TA, and the contact state of the idle switch are reset. Input signals from each sensor, such as a signal to represent, are sequentially read.

Next, in SA2, it is determined whether or not the vehicle is coasting, that is, power-off traveling in which the accelerator pedal is not operated, based on, for example, the contact state of the idle switch. If the determination at SA2 is denied, the control routine is terminated and another control is started. If the determination is affirmed, the orifice switching period determining means 304 and the line pressure increasing period determining means 310 in SA3 to increase value P1 of the line pressure P _L, the line pressure P2 during the shift period, the line pressure rising period T2 of raising the coast downshift command, the line pressure P _L to the increase value P1, the coast-down shift command large The orifice switching period T1 for holding the orifice is determined and set by reading or calculation.

At subsequent SA4, the linear solenoid valve SL
The line pressure P _L by changing the control pressure P _S which is output from the T is raised to the rise value P1. Then, after the contents of the timer t _a is incremented at SA5, at SA6, the contents t _a timer which is caused to counting operation in coastdown gear shift command after the SA
It is determined whether the line pressure rise period T2 set in 3 has not been reached. Initially, the determination at SA3 is affirmative, so the above SA5 and subsequent steps are repeatedly executed. However, since the line pressure rising period T2 from the coast downshift command has passed determination in SA6 is negative, at SA7, the line pressure P _L is lowered from its raised value P1 to the line pressure P2 during the shift period. T ₂ in FIG. 9 shows this state. In this embodiment, the above SA
4 and SA7 correspond to the line pressure changing means 312.

[0064] Then, after the contents of the timer t _a is incremented at SA8, in SA9, it reaches the orifice switching period T1 contents t of the timer t _a which is caused to counting operation is set in SA3 in the coast downshift command after It is determined whether not. Initially, the determination at SA9 is affirmative, so the above SA8 and subsequent steps are repeatedly executed. However, when the orifice switching period T1 elapses from the coast down shift command, the SA9
Is denied, the hydraulic oil flow rate changing means 30
In SA10 corresponding to No. 8, the oil passage 192 for supplying the hydraulic oil to the clutch C1 engaged to realize the 4 → 3 downshift is switched from the large orifice to the small orifice. This state is indicated by t ₃ in FIG.

Subsequently, the end of the coast down shift is determined.
At SA11 corresponding to the means 306,
Whether or not the 4 → 3 downshift is completed is determined by, for example, (N_o
× γ _Three-N_T) Is larger than a predetermined criterion value Δn.
It is determined whether it is small. This criterion value Δn is
Turbine speed N_TAnd output shaft rotation speed N_oThird speed
Gear ratio γ_ThreeWhether the difference from the value multiplied by is close to zero
Or the actual turbine speed N_TAnd output shaft speed
Degree N_oAnd the ratio N_T/ N_oIs the gear ratio γ of the third speed_ThreeTo
Set to zero which is set in advance to determine whether or not
It is a close value.

[0066] Initially the SA11 to determine the SA11 is negated is repeatedly executed, and increased turbine speed N _T and substantially reaches the rotation speed N _o × γ, 4 → 3 downshift is substantially finished In this state, the determination at SA11 is affirmed. Therefore, in the subsequent SA12, the contents of the timer t _b which is caused to counting operation in the transmission ended after is incremented. T ₄ time in FIG. 9 shows this state.

Next, at SA13, the timer t
_It is determined whether or not the content of _b has not reached the preset determination reference value T3. Initially, the determination at SA13 is affirmative, so the above SA12 and subsequent steps are repeatedly executed. While SA12 and below are repeatedly executed, SA
If the determination in step 13 is negative, the hydraulic oil amount changing means 30
At SA14 corresponding to 8, the orifice of the oil passage 192 for supplying the hydraulic oil to the clutch C1 is returned from the small orifice to the large orifice. T _{5 in} FIG.
Indicates this state.

As described above, according to the present embodiment, the orifice switching from the time when the command for coast down shifting during coasting traveling is output by the hydraulic oil flow rate changing means 308 (SA10, SA14) until the start of shifting is performed. Until the period T1 elapses, the orifice of the oil passage 192 that supplies the working oil to the clutch C1, which is the engagement side hydraulic friction engagement device, is switched to the large orifice having a small flow resistance, but the orifice switching period T1 elapses. Then, the orifice of the oil passage 192 is switched from the large orifice to the small orifice having a larger flow resistance. Therefore, the supply of the hydraulic oil to the clutch C1 is promoted after the 4 → 3 coast downshift command, and the engagement timing is made earlier, and after the clutch C1 starts to be engaged, the hydraulic oil is supplied to the clutch C1 through the small orifice. And the accumulator 160 is supplied to the accumulator 160 connected thereto and the accumulating operation period of the accumulator 160 is extended to reduce the increase in the engagement pressure of the clutch C1. The shift shock is suitably eliminated, and the shift responsiveness of the coast downshift is suitably improved. That is, without changing the large orifice or the accumulator related to the supply of the hydraulic oil to the clutch C1, the shift shock due to the insufficient capacity of the accumulator is suppressed in the coast down shift, and the shift responsiveness of the coast down shift can be obtained. is there.

Also, according to the present embodiment, when the line pressure changing means 312 (SA4, SA7) determines that the coast downshift determination means 302 has output a command for coast downshift during coasting of the vehicle. , Clutch C1
The line pressure PL is increased to a predetermined value P1. When a line pressure increase period T2 that is shorter than the period from the coast down shift command to the start of the shift elapses, the line pressure P _L is increased. _{Lower L} , that is,
Since the line pressure P _L is raised to an elevated value P1 in the line pressure rising period T2, the return spring 236 of the clutch C1 is further shortened return spring period until the friction of the friction material is started elastically deformed Therefore, the shift response of the coast down shift is further enhanced.

Further, according to the present embodiment, when the coast-down shift end determining means 306 (SA11) determines that the coast-down shift has ended, the hydraulic oil flow rate changing means 308 (SA14) operates the clutch C1. Since the orifice of the oil passage 192 for supplying oil is switched from the small orifice to the large orifice and returned, it is not necessary to switch from the large orifice to the small orifice at the time of the 4 → 3 coast downshift command, and the small orifice is not required. Even if foreign matter is clogged, the downshift can be achieved by supplying hydraulic oil to the clutch C1 through the large orifice instead.

As described above, one embodiment of the present invention has been described with reference to the drawings. However, the present invention can be implemented in another mode different from the above embodiment.

For example, in the above-described embodiment, the coast-down shift control of the gear stage of the automatic transmission 14 is performed as follows.
Although the description has been made focusing on the amount of hydraulic oil supplied to the clutch C1, which is the engagement-side hydraulic friction engagement device during the downshift from the fourth speed to the third speed, and the line oil pressure P _L ,
A downshift other than the downshift from the fourth speed to the third speed, for example, a downshift from the third speed to the second speed,
The present invention may be applied to the case where the downshift from the first speed to the first speed is performed, or may be applied to the downshift from the fifth speed to the fourth speed when the automatic transmission 14 is the fifth forward speed. Good.

Further, in the above-described embodiment,
Instead of the throttle opening TA
θ_ACC, Fuel injection amount F, intake pipe negative pressure P_INEngine
An amount representing the load may be used, or the turbine speed N
_TInstead of the input shaft speed N _IN, Clutch C1 rotation speed N
_C1, Output shaft speed N_OUT× γ or the like may be used.

[0074] Further, in the embodiment described above, but the line pressure P _L line pressure increase period within T2 from the coast downshift command has been raised to an elevated value P1, the operation of the rising value P1 accumulator 160 This is for quickly bringing the clutch C1 into a state immediately before its engagement within a range not to be started so much, so that it can be set to various values depending on the configuration of the clutch C1 and the accumulator 160, and shift responsiveness does not matter so much. Depending on the type of vehicle, the line pressure changing means 312 may not necessarily be provided.

What has been described above is merely an embodiment of the present invention, and the present invention can be variously modified without departing from the gist thereof.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a vehicle including a hydraulic control device for an automatic transmission according to an embodiment of the present invention.

FIG. 2 is a table showing gears in an automatic transmission of the vehicle shown in FIG. 1 and operating states of a friction engagement device for establishing the gears.

FIG. 3 is a hydraulic circuit diagram showing a configuration of a part of the hydraulic control circuit of FIG. 1 that generates a line hydraulic pressure.

FIG. 4 is a part of the hydraulic control circuit of FIG.
FIG. 2 is a hydraulic circuit diagram showing a configuration of a part that supplies hydraulic oil to a brake 1 and a brake B1.

FIG. 5 is a cross-sectional view illustrating an example of a configuration of a clutch C1.

FIG. 6 is a functional block diagram for explaining a main part of a control function of the electronic control unit for shifting shown in FIG. 1;

FIG. 7 is a diagram illustrating a relationship stored in advance used in the orifice switching period determination means of FIG. 6;

FIG. 8 is a flowchart showing an essential part of the control operation of the shift electronic control device of FIG. 1 and showing an example of the contents of a main routine performed based on the functional block diagram of FIG. 6;

9 is a time chart showing a rotation speed, a torque, and a hydraulic pressure during a coast downshift period that change in association with the control operation of the shift electronic control device of FIG. 8;

[Explanation of symbols]

 14: Automatic transmission for vehicle 192: Oil path 302: Coast-down shift determining means 306: Coast-down shift end determining means 308: Hydraulic oil flow rate changing means 312: Line pressure changing means C1: Clutch (engagement side hydraulic friction Joint equipment)

Continuation of front page (72) Inventor Tatsuya Ozeki 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Co., Ltd. (56) References JP-A-2-118262 (JP, A) JP-A-2-203065 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48

Claims (3)

(57) [Claims] An automatic transmission for a vehicle includes a plurality of hydraulic frictional engagement devices for switching gears, and among the plurality of hydraulic frictional engagement devices, a downshift of the automatic transmission for a vehicle is provided. A hydraulic control device for an automatic transmission for a vehicle, wherein a flow rate of hydraulic oil supplied to an engagement-side hydraulic friction engagement device frictionally engaged with the vehicle is changed by switching an orifice during the downshift. Coast-down shift determining means for determining whether or not a command for coast-down shifting during coasting of the vehicle has been output; and determining that a command for downshifting during coasting of the vehicle has been output by the coast-down shifting determining means. the from
Until the orifice switching period determined as a period up to any point in time until the start of the downshift, the orifice of the oil passage that supplies the operating oil to the engagement side hydraulic friction engagement device passes through the orifice of the flow resistance. A hydraulic oil flow rate changing means for switching the orifice of the oil passage from the large orifice to a small orifice having a larger flow resistance when the orifice switching period elapses. Hydraulic control device for automatic transmission. 2. A coast-down shift end determining means for determining whether or not the coast-down shift has been completed,
The hydraulic oil flow changing means, when the coast down shift end determining means determines that the coast down shift has been completed, an orifice of an oil passage for supplying hydraulic oil to the engagement side hydraulic friction engagement device. The hydraulic control device for an automatic transmission for a vehicle according to claim 1, wherein the pressure is changed from the small orifice to the large orifice. 3. The coast downshift determining means
The coast downshift command is output during coasting of the vehicle.
If it is determined that the hydraulic pressure has been
When a certain line pressure is increased to a predetermined value,
From the downshift command to the start of the shift or before
When the line pressure rise period set as
It further includes a line pressure changing means for reducing the in-pressure.
The hydraulic control apparatus for an automatic transmission for a vehicle according to claim 1, wherein: