JPS6213850A - Line pressure control device for automatic transmission - Google Patents

Abstract

PURPOSE:To reduce a select shock, by providing a control means for the line pressure to a speed change selecting actuator while a delay means delaying the action of said control means for a predetermined time when a transmission is selected from the range with no action of an engine brake to the range applying the engine brake. CONSTITUTION:A spool position in a 3-4 shift valve 65 is controlled by a 3-4 shift solenoid valve 53, providing a delay means of timer or the like in a control system, and a line pressure introduced through a line 151. When said spool is placed in an off-position, the line pressure communicates with an actuator 42 for a direct clutch and a release side 46B of an overdrive brake 46. While increase timing of the line pressure, when a range select is performed, is controlled by providing a backup control valve 70 in a line 152 from a port (d) of a manual valve 61. Accordingly, a transmission can reduce a select shock from the range with no action of an engine brake to the range applying the engine brake.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a line pressure control device for an automatic transmission.

(Prior Art) In general, an automatic transmission includes a speed change gear mechanism, a speed change switching means comprising a friction element such as a clutch and a brake that switches the power transmission path of the speed change gear mechanism to perform a speed change operation, and a speed change switching means that operates the speed change switching means. It is configured to include a fluid actuator such as a hydraulic servo, and a control means such as a valve mechanism that controls the supply of pressure fluid to the fluid actuator, and the speed change switching means is operated by the fluid actuator. The required gear stage is obtained by switching the power transmission path.

Furthermore, in such an automatic transmission, the operating state can be changed between a range in which engine braking does not apply (for example, D range) and a range in which engine brake does apply (for example, L range or 2 range) by controlling the speed change switching means.
It is configured so that it can be selected.

Incidentally, a problem with such automatic transmissions is the engagement force of friction elements such as brakes and clutches when selecting from a range where engine braking does not work to a range where engine braking does work. In other words, when selecting from a range where engine braking does not apply to a range where engine braking applies, the torque loaded on each friction element increases, resulting in insufficient fastening force for each friction element, which reduces power transmission. Performance may deteriorate.

Conventionally, as a means to solve such problems, when the transmission is selected from a range in which engine brake is not applied to a range in which engine brake is applied, line pressure (operating pressure) of pressurized fluid (for example, pressure oil) is ) is set higher than the line pressure in the range where engine braking does not apply, thereby compensating for the lack of engagement force of each friction element and maintaining a high level of transmission performance (for example, (Refer to Japanese Patent Publication No. 1983-44108).

However, in this type of conventional automatic transmission, when selecting from a range where engine braking does not apply to a range where engine braking applies, line pressure is immediately changed based on a select signal sent in conjunction with manual valve operation. As a result, gear shifting operations using the gear shifting means are performed under high line pressure after the pressure has increased, and as a result, unpleasant shocks (select shocks) occur during gear shifting operations. , there was a problem that the drivability of the car was impaired.

(Purpose of the Invention) The present invention aims to improve the problems pointed out in the section of the prior art described above, and aims to reduce the selection shock as much as possible when selecting from a range where engine braking does not apply to a range where engine braking applies. It is an object of the present invention to provide a line pressure control device for an automatic transmission that reduces the line pressure of the automatic transmission.

(Means for Achieving the Object) The present invention provides a speed change gear mechanism, a speed change switching means for changing the speed by switching the power transmission path of the speed change gear mechanism, and the speed change switching means as a means for achieving the above object. and a control means for controlling the supply of pressure fluid to a hydraulic actuator for operating the engine, and a range in which the engine brake is applied and a range in which the engine brake is not applied can be selected by controlling the transmission switching means. In the transmission, line pressure control means increases the line pressure supplied to the fluid actuator when selecting from a range in which engine braking does not apply to a range in which engine braking applies, and a line pressure control means for increasing the line pressure supplied to the fluid actuator, and delaying the line pressure by a predetermined time by a selection operation at the time of selection. and delay means for activating the line pressure control means.

(Function) According to the present invention, when selecting from a range in which engine brake does not act to a range in which engine brake acts, the line pressure control means is activated after a predetermined time delay from the selection operation by the above means, so that the selection operation is This is carried out under line pressure during the rise, resulting in the effect of reducing select shock as much as possible.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 shows a power transmission section and its hydraulic control circuit of an automatic transmission according to an embodiment of the present invention.

(Configuration of automatic transmission) The automatic transmission includes a torque converter 1, a multi-stage gear transmission 2, and an overdrive planetary gear transmission mechanism 3 disposed between the torque converter 1 and the multi-stage gear transmission 2. have.

The torque converter 1 includes a pump 5 coupled to an engine output shaft 4, a turbine 6 disposed opposite the pump 5, and a stator 13 disposed between the pump 5 and the turbine 6. Further, a comparator output shaft 8 is coupled to the turbine 6 . Further, a lock-up clutch 9 is provided between the converter output shaft 8 and the pump 5. This lock-up clutch 9 is a torque converter! It is always urged in the engagement direction by the hydraulic pressure circulating therein, and is released and held by supplying release pressure oil from the outside into the pressure chamber 9a.

The multi-stage gear transmission 2 is a front stage planetary gear mechanism! The sun gear 12 of the front planetary gear mechanism IO and the sun gear 13 of the rear planetary gear mechanism 11 are connected by a connecting shaft 14. The input shaft 15 of the multi-stage gear transmission 2 is connected to the connecting shaft 14 via a front clutch 16 and to the front planetary gear mechanism 1 via a rear clutch 17.
0 internal gear 18, respectively. A second brake 19 is provided between the connecting shaft 14, that is, the sun gear 12.13, and the transmission case. The planetary carrier 20 of the front planetary gear mechanism IO and the internal gear 21 of the rear planetary gear mechanism 11
is connected to the output shaft 22. Further, a low reverse brake 24 and a one-way clutch 25 are provided between the planetary carrier 23 of the rear planetary gear mechanism 11 and the transmission case.

This multi-gear transmission 2 has a conventionally known transmission mechanism, and has three forward speeds and one reverse speed, and includes a front clutch 16, a puller clutch 17, a second brake 19, and a low reverse brake 24. As will be described later, a desired gear position can be obtained by appropriately operating a hydraulic actuator.

The overdrive planetary gear transmission mechanism 3 includes a planetary carrier 27 that rotatably supports the planetary gear 26.
and a sun gear 28 coupled to an internal gear 30 via a direct clutch 29. An overdrive brake 31 is provided between the sun gear 28 and the transmission case, and the internal gear 30 is connected to the input shaft 15 of the multi-gear transmission 2.

This overdrive planetary gear transmission mechanism 3 is operated by the overdrive brake 31 when the direct clutch 29 is engaged.
When released, the converter output shaft 8 and input shaft 15 are directly connected, and then, when the overdrive brake 31 is engaged and the direct clutch 29 is released, the converter output shaft 8 and the human power shaft are connected. 15 in an overdrive manner.

This transmission operates a manual valve 61 of a hydraulic control circuit (to be described later) manually to operate each friction element (clutch and brake) of the multi-stage gear transmission 2 and the overdrive planetary gear transmission mechanism 3 as appropriate. The control pattern for each friction element is set as follows for each range in the same manner as in the conventional structure.

In this case, engine braking is applied by the second brake 19 in the second gear of the 2nd and l-ranges, and by the low reverse brake 24 in the first gear of the l-range.

(Hydraulic control circuit) (Configuration) The hydraulic control circuit operates each friction element in the operation pattern shown in Table 1 above in response to the driver's selection operation so that a predetermined gear can be obtained. It has a simple circuit configuration, which will be explained in detail below.

In the hydraulic control circuit, reference numeral 50 denotes a hydraulic pump,
The hydraulic oil discharged from the hydraulic pump 50 is regulated to a predetermined pressure by a pressure regulating valve 62 and introduced into a manual valve 61 via a pressure line 101.

The manual valve 61 has five ports that can communicate with the pressure line 101. That is, (D, 2.1)
A boat a communicates with the pressure line 101 in the three ranges of (D, 2), a boat b communicates with the pressure line 101 in the two ranges (D, 2), and a boat c communicates with the pressure line 101 only in the R range.
, a boat d communicating with the pressure line 101 in four ranges (P, R, 2, 1), and (R.

The two ranges (l) have a boat e that communicates with the pressure line lot.

Boat a is connected to line 111.

This line 111 has three pilot lines at its ends: an I-2 shift solenoid valve 51 that controls the operation of the 1-2 shift valve 63, and an aperture 86.
a first pilot line 102 equipped with a 2-3 shift solenoid valve 52 that controls the operation of a 2-3 shift valve 64, and a second pilot line 10 equipped with a throttle 87.
3, and 3-4 that controls the operation of the 3-4 shift valve 65.
Shift solenoid valve 53 and throttle ss4. The third prepared
It branches into a pilot line 104. By turning on (energizing) each solenoid valve 51, 52, 53, each drain line 105 is connected to the drain line 105.
, 106, 107 and each pilot line +0
2. Set pilot pressure on 103 and 104 respectively,
This moves each shift valve 63, 64, 65 from the OFF position (rightward moving position) to the ON position (leftward moving position) to open and close the hydraulic circuit of the associated friction element, and its operation pattern are set according to each range and gear as shown in Table 2 below.

Table 2 In addition, in Table 2, 3-4 shift solenoid valve 5
3 is OFF only in 3rd gear and OFF in other gear positions.
However, in applying the present invention (i.e., when selecting from D range to L range or 2 range, this 3-4 shift solenoid controls the line pressure to be performed with a predetermined time difference from the selection operation). especially for l speed and 2
It is also ON at high speeds. Therefore, 3-
4 shift solenoid valve 53 to 3-4 shift valve 6
If the switch is used only for the operation control of No. 5, it may be set to OFF also in the first and second speeds as indicated in parentheses.

The first pilot line 102 is a first pilot line 102 that communicates with the right end portion (pilot pressure load portion) of the 1-2 shift valve 63 on the downstream side of the 1-2 shift solenoid valve 51.
A second branch line 10 that communicates with the branch line 102a and the right end portion (pilot pressure load portion) of the cutback valve 66
It is branched into two lines 2b.

Line pressure is supplied to both ends of the 1-2 noft valve 63 via a line 112 branching from the line I11 and a line 113 further branching from the line I12.
A manual valve 61 is located in the middle of the shift valve 63.
Line pressure is introduced through lines 122 communicating with the boat e. Note that this line 122 is communicated with the line 123 when the 1-2 soft valve 63 is in the OFF position, that is, when the shift position is in the 1st speed position. Also, this line 123 (
It is connected to the low reverse brake actuator 44. On the other hand, the line +13 is communicated with the line 161 when the I-2 shift valve 63 is in the ON position, that is, in a shift position other than the shift position.

This line 161 is connected to the engagement side 45A of the second brake actuator 45.

Also, a reducing valve 68 is connected to this line 161.
An accumulator 79 and a one-way orifice 82 are provided, the back pressure of which is controlled by.

The 2-3 shift valve 64 is set to 0N- by pilot pressure introduced from the line 103 connected to its right end.
It is controlled to be turned off. This 2-3 shift valve 64 has a boat b of the manual valve 61.
A line 121 communicating with the boat C and a line 131 communicating with the boat C are connected to each other.

Of this line 121 and line +31, line +21
is connected to line 132 when the 2-3 shift valve 64 is in the ON position (i.e., 3rd or 4th gear shift position), and line 13+ is connected to the OFF position of the 2-3 shift valve 64 (i.e.,
The gears are selectively connected to the line 132 at the first or second gear position. still,
A reducing valve 67 and a one-way valve 85 are connected in parallel to the line 131.

On the downstream side, the line 132 has a line 136 connected to the front clutch actuator 41 and a release side 45 of the second brake actuator 45.
It is branched into a line 138 that connects to B. A one-way orifice 74 is installed on the upstream side of the branch part of this line 132 and acts to throttle the hydraulic fluid flowing from the 2-3 shift valve 64 toward the branch part. or,
A one-way orifice 75 that acts to throttle the hydraulic fluid in the direction from the second brake actuator 45 to the 2-3 shift valve 64 side is installed at a position immediately downstream of the above-mentioned branch part of the line +38. moreover,
A valve is operated by pilot pressure introduced from a vacuum throttle valve 69 via a line 155 between an intermediate position between the branch part of the line 132 and the one-way orifice 74 and a position downstream of the one-way orifice 75 of the line 138. A line 140 equipped with a 3-2 timing valve 72 that is connected to the 3-2 timing valve 72 and a line 137 that includes a 3-2 timing valve 73 that is operated by pilot pressure introduced from the primary section 47B of the governor 47 via a line 163 are connected in parallel. It is connected to the. Also, the above lines 137 and 138 of line 138
There is a one-way orifice 8 further downstream from the branch part.
3 is provided.

Further, in the line +36, there is a one-way accumulator 78 whose back pressure is controlled by the line pressure supplied via the line +39 branching from the line 132, which acts to throttle the hydraulic fluid flowing out from the accumulator 78. It is connected via an orifice 81. Note that back pressure control of the accumulator 78 is performed by the reducing valve 67 described above.

The third pilot line +04 is a first branch line +04a that communicates with the right end of the 3-4 shift valve 65 on the downstream side of the 3-4 shift solenoid valve 53.
It is branched into two branch lines: and a second branch line +04b that guides pilot pressure to a backup control valve 70, which will be described later.

A line 141 branching from the pressure line 101 is connected to an intermediate portion of the 3-4 shift pulp 65. This line 141 is line
be communicated with.

On the downstream side, this line +42 is connected to a line +43 that communicates with the direct clutch actuator 42.
and a line 144 communicating with the release side 46B of the overdrive brake 46, and an oil pressure switch 90 is installed at a position upstream from the branch. Also, the line 143 has an accumulator 7.
7 is provided. In addition, overdrive brake 46
The fastening side 46A of is connected to the pressure line lot via line +48.

On the other hand, a line 151 that communicates with the boat d of the manual valve 61 is connected to the left end of the 3-4 shift valve 65, and the spool of the 3-4 shift valve 65 is in a select position other than the D range. is the line 1
Forced OF by line pressure introduced through 51
Positioned and held at position F. Further, the vacuum throttle valve 6 is branched from this line 151.
9, a throttle backup valve 71 and a backup control valve 70 are connected in series, and the backup control valve 70
is installed so as to be located downstream of the throttle backup valve 71. This throttle pack up knob 71 causes the line pressure standing on the line 152 to act on the vacuum throttle valve 69 in the 2 range and the 1 range, and drives the pressure regulating valve 62 in the pressure increasing direction via the vacuum throttle valve 69. This acts to increase the line pressure. Further, the backup control valve 70 includes the throttle backup valve 71 and the vacuum throttle valve 6.
9 and when pilot pressure is established in the branch line 104b, that is, when the 3-4 shift solenoid valve 5
When the valve 3 is turned on, the line 152 is opened to enable the throttle backup valve 71 to increase the line pressure, and is provided when the present invention is applied.

That is, in the conventional hydraulic circuit, the throttle backup valve 71 and the vacuum throttle valve 69 are directly connected, and when line pressure builds up in the line 151, throttle pressure is immediately and automatically applied to the vacuum throttle valve 69. However, in this embodiment, by providing this backup control valve 70, the line pressure is increased.
Even when line pressure is applied to the vacuum throttle valve 51, no throttle pressure is applied to the vacuum throttle valve 69 unless pilot pressure acts on the backup control valve 70 (this action will be further explained later).

The line 112 has a line 116 communicating with the rear clutch actuator 43 at its downstream end, and a line 117 communicating with the secondary portion 47A of the governor 47.
It is divided into two lines. This line 116 includes an accumulator 80 and a one-way orifice 84.
are provided for each. Furthermore, this line 112
The line 114 branching from the accumulator 7
9 reducing valves 68 for adjusting back pressure are provided.

Further, the line 149 is communicated with the operating chamber 9a of the lock-up clutch 9 through a line 146 which is provided with a lock-up valve 76 and a throttle 91 in the middle thereof. The pilot line +45 of this lock-up valve 76 has a calibration 89 and a lock-up solenoid valve 5.
4, and the lock-up clutch 9 is engaged when the lock-up solenoid valve 54 is turned on, pilot pressure is established in the line 145, and the line 146 is drained by the spool. There is. In this embodiment, the lock-up clutch 9 is engaged only between the second and fourth speeds of the D range.

(Operation and Effects) The automatic transmission Z, which is equipped with the power transmission part and the hydraulic control circuit as described above, controls the four solenoid valves 51, 52, 53, and 54 of the hydraulic control circuit according to the throttle opening as shown in FIG. 0N-OF according to the control patterns shown in Table 2 by control signals output from the controller based on various engine state detection elements such as signals and engine speed signals.
By performing F control, each friction element operates according to the operation pattern shown in Table 1, and a predetermined gear position is obtained. Also, in this case, in this example,
By applying the present invention, a delay means such as a timer is provided in the control system of the 3-4 shift solenoid valve 53 as shown in FIG. 1 and FIG. The timing at which the line pressure rises when selecting the range is controlled.

The operation of the hydraulic control circuit and its effect will be described below, taking as an example the case where the engine brake is selected from the 4-reverse state in the D range where the engine brake does not work to a range where the engine brake works, such as 2nd gear (fixed at 2nd speed).

(When traveling in D range) In this case, port a and port b of manual valve 61 are in communication with pressure line 101, and three shift solenoid valves 51, 52, and 53 are all in the ON position. Therefore, in the 1-2 shift valve 63, the line 113 and the line 161 communicate with each other, and line pressure is applied to the engagement side 45A of the second brake actuator 45, and in the 2-3 shift valve 64, the line 121 and the line 132 communicate with each other. are in communication with each other, and line pressure is applied to the release side 45B of the front clutch actuator 41 and the second brake actuator 45, respectively. Therefore, the front clutch 16 is engaged and the second brake 19 is released.

On the other hand, since the line 123 is drained, the low reverse brake 24 is released. That is, the engine brake is not applied.

Also, in the 3-4 shift valve 65, the line 142
and line 151 are both drained. Therefore, the direct clutch 29 is released. On the other hand, in the overdrive brake 46, line pressure is introduced only to the engagement side 46A via the pressure line 101, and the release side 46B is drained, so the overdrive brake 31 is in the engagement state.

Furthermore, line pressure is introduced into the line 112,
Therefore, the rear clutch 17 is in the engaged state. By operating each friction element in this manner, four-way travel in the D range is realized.

On the other hand, in this state, since the line 151 is drained, the 3-4 shift solenoid valve 53 is turned ON.
Even if the backup control valve 70 is activated and the pilot pressure is generated in the branch line l04b and the backup control valve 70 is set to the ON position, no line pressure acts on the vacuum throttle valve 69.

Therefore, the line pressure is maintained on the low pressure side.

(When selecting the 2nd range) When the 2nd range is selected from the D range, the 1-2 shift solenoid valve 51 is held in the ON position and the 2nd range is selected.
-3 shift solenoid valve 52 is turned OFF' at the same time as the selection operation. On the other hand, the 3-4 shift solenoid valve 53 is ultimately held at the ON position, but this does not mean that the ON position state before the selection operation is connected as is after the selection operation; In other words, it turns on at the same time as the selection signal is sent.
The switch is once switched from the OFF position to the OFF position and held as it is for a predetermined time set by the delay means, and after the predetermined time is switched from the OFF'F' position to the ON position and held as it is. Therefore, even if line pressure is generated in the line 151 at the same time as the selection operation and a predetermined line pressure is generated by the throttle backup valve 71, the 3-4 shift solenoid valve 53 is turned off.
Since it is in the F state and no pilot pressure is generated in the line 104b, the backup control valve 70 is OFF.
The line pressure is maintained at the same position, and therefore the line pressure is not increased by the throttle pressure, and the line pressure is maintained at a low pressure state.

However, on the other hand, the I-2 shift valve 63 continues to be in the ON state, the 2-3 shift valve 64 is turned off at the same time as the selection operation, and the 3-4 soft valve 65 is turned off at the same time as the selection operation as described above. , the opening of the front clutch 16, the engagement of the direct clutch 29, the engagement of the second brake 19, and the release of the overdrive brake 31 are performed under line pressure in the middle of startup. Therefore, the shock (select shock) accompanying the engaging/disengaging operation of each friction element is compared to the case where the engaging/disengaging operation is performed in a state where the line pressure is increased due to the throttle pressure acting on the vacuum throttle valve 69. This will be reduced as much as possible.

On the other hand, when the time set by the delay means has elapsed, the 3-4 shift solenoid valve 53 is turned ON, thereby generating pilot pressure in the line +04b. Therefore, the backup control valve 70 is turned ON.
When activated, the line 152 is connected, line pressure is applied to the vacuum throttle valve 69 from the throttle backup valve 71 side via the backup control valve 70, and hydraulic oil from the vacuum throttle valve 69 is applied to the spool of the pressure regulating valve 62. On the other hand, it acts in the pressure increasing direction, and the line pressure is increased by a predetermined amount. That is, in this embodiment, the selection signal is transmitted (switching operation from D range to 2 range) as shown in FIG.
Not at the same time as the select signal, but for a predetermined time T
After the line pressure has passed, the line pressure is increased, and while the line pressure is rising, each friction element is engaged and disengaged, thereby reducing the selection shock.

In these two ranges, engine braking is applied by engaging the second brake 19, but after selection is completed, the line pressure is increased and the engagement force of each friction element is increased, so the engine brake is applied. Even if the brake is applied and the load torque at each friction element increases, no slipping occurs at each friction element, and good power transmission performance is ensured.

In this case, better results can be obtained by changing the delay time according to the engine operating condition, for example, the vehicle speed. In other words, when selecting from D range to 2nd range or Lunge while driving at high speed, the engine braking force that is applied at the same time as selection is greater than when selecting at low speed, and therefore, if the line pressure is low, Since there is a risk of slippage occurring in each friction element, in this case, it is preferable to set the delay time to be relatively short and increase the line pressure as soon as possible, mainly with the aim of ensuring power transmission performance. On the other hand, when selecting at low speeds, the acting force of the engine brake is relatively small and there is relatively little risk of slipping on each friction element, so in this case, the above delay time is mainly aimed at reducing the selection shock. It is best to set it relatively long.

In this embodiment, the friction elements such as the brake clutch correspond to the speed change switching means in the claims, and each actuator such as the front clutch actuator 411 and the direct clutch actuator 42 corresponds to the fluid in the claims. It corresponds to a manual valve 61 and each shift solenoid valve 51, 52 .
53 and each shift valve 63, 64, 65 correspond to the control means in the claims, and the 3-4 shift solenoid pulp 53 and the backup control valve 70
corresponds to the line pressure control means in the claims.

(Effects of the Invention) The line pressure control device for an automatic transmission of the present invention includes a speed change gear mechanism, a speed change switching means for changing the speed by switching the power transmission path of the speed change gear mechanism, and a fluid for operating the speed change switching means. control means for controlling the supply of pressure fluid to the automatic transmission actuator; , line pressure control means for increasing the line pressure supplied to the fluid actuator when selecting from a range in which engine braking does not apply to a range in which engine braking applies; The present invention is characterized by comprising a delay means for activating the control means.

Therefore, according to the line pressure control device for an automatic transmission of the present invention, when selecting from a range where engine braking does not apply to a range where engine braking applies, the line pressure control means operates with a predetermined time delay after the selection operation; As a result, the selection operation is performed under the line pressure while the pressure is rising, so that the effect of reducing the selection shock as much as possible can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of an automatic transmission equipped with a line pressure control device according to an embodiment of the present invention, Fig. 2 is a control system diagram of the automatic transmission shown in Fig. 1, and Fig. 3 is a system diagram of an automatic transmission equipped with a line pressure control device according to an embodiment of the present invention. It is a control time chart. l...Torque converter 2...Multi-stage gear transmission 3...Planetary gear transmission mechanism 10...Front stage planetary gear mechanism 11...Rear stage planetary gear mechanism 16...・Front clutch 17...Rear clutch 19...Second brake 1 Noki 24...Low reverse brake 29...Direct clutch 31...Overdrive brake 41...Front clutch actuator 42・
...Direct clutch actuator 43...Rear clutch actuator 44...
・Low reverse brake actuator 45・・Second brake actuator 46・
... Overdrive brake 47 ... Governor 51 ... 1-2 shift solenoid valve 52 ...
・2-3 shift solenoid valve 53...3-4 shift solenoid valve 54...Lock-up solenoid valve 61...Manual valve 62...Pressure regulating valve 63...1-2 software Valve 64...2-3 Shift valve 65...3-4 Shift valve 69...Vacuum throttle valve 70...
Backup control valve 71... Throttle backup valve Applicant Mazda Co., Ltd. Figure 3

Claims (1)

[Scope of Claims] 1. Controlling the supply of pressurized fluid to a speed change gear mechanism, a speed change means for changing the speed by switching the power transmission path of this speed change gear mechanism, and a fluid actuator that operates this speed change change means. In the automatic transmission, the automatic transmission is equipped with a control means for controlling the transmission, and is configured to be able to select between a range in which engine braking is applied and a range in which engine braking is not applied by controlling the transmission switching means. A line pressure control means for increasing the line pressure supplied to the fluid actuator when selecting the operating range, and a delay means for activating the line pressure control means after a predetermined period of time in response to the selection operation at the time of selection. A line pressure control device for an automatic transmission characterized by: 2. The line pressure control device for an automatic transmission as set forth in claim 1, wherein the delay means is adapted to change the delay time in accordance with the operating condition of the vehicle.