JPS6184448A - Hydraulic control device in automatic speed change gear unit - Google Patents

Abstract

PURPOSE:To prevent shocks upon shift operation of an automatic speed change gear unit having no friction engagement device which is not engaged at the first shift stage but is engaged at every shift stage higher than the first shift stage, by enabling a cut-back valve for controlling a throttle valve to be controlled at every shift stage higher than the first shift stage. CONSTITUTION:In a hydraulic control device including a plurality of passages in such a combination that hydraulic pressure is effected at least one of the passages at every shift stages other than the first shift stage, being composed of a passage for an overdrive brake B0 and a passage for a second brake B2, there are provided a throttle valve 200 for controlling line pressure and a cut- back valve 100 for controlling the former valve 200. The cut-back valve is composed of a spool 108 provided with rands 102, 104, 106 having face areas A1-A3 which are different from each other (A3<A1<A2). Further, these areas A1-A3 are set to be satisfy the following formulae: PB2.A1>PTH.A2, PBO (A2-A1)>PTH.A2.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to hydraulic control of automatic transmissions, and in particular, the hydraulic pressure of automatic transmissions equipped with a so-called cut-back function that reduces line pressure at a predetermined time to reduce power consumption of an oil pump. Concerning improvements to control devices.

[Conventional technology]

With the rapid spread of automatic transmissions for vehicles in recent years, main transmissions that can automatically change gears depending on vehicle speed, throttle opening, etc. are being used to improve fuel efficiency. A so-called overdrive device with a ratio of 1 or less is often installed in series as an auxiliary transmission. That is, as an example of this type of automatic transmission, there is one shown in FIG. 4. This automatic transmission includes a transmission section, a torque converter 20, an overdrive mechanism 40 as a sub-transmission, and an underdrive mechanism 6O as a main transmission with three forward speeds and one reverse speed. Equipped with The torque converter 20 includes a pump 21 and a turbine 2.
2, a stator 23, and a lock-up clutch 24. The pump 21 is connected to the crankshaft 10 of the engine 1, and the turbine 22 is connected to a carrier 41 of a planetary gear system in an overdrive mechanism 4o. In the overdrive mechanism 40, a planetary pinion 42 rotatably supported by the carrier 41 meshes with a sun gear 43 and a ring gear 44. Further, an overdrive clutch Go and a one-way clutch Fo are provided between the sun gear 43 and the carrier 41-, and an overdrive brake Ba is provided between the sun gear 43 and the housing Hu. The underdrive mechanism 60 is provided with two rows of planetary gears, one on the front side and the other on the rear side. This planetary gear system consists of a common sun gear 61, a ring gear 62, 63, a planetary pinion 64, 65, and a carrier 66, 67, respectively. A ring gear 44 of the overdrive mechanism 40 is connected to the ring gear 62 via a forward clutch C1. Further, a direct clutch C2 is provided between the ring gear 44 and the sun gear 61. Further, the carrier 66 is connected to the ring gear 63, and the carrier 66 and ring gear 63 are connected to the output shaft 7o. On the other hand, a first and reverse brake B3 and a one-way clutch F2 are provided between the carrier 67 and the housing Hu, and a second brake is provided between the sun gear 61 and the housing Hu via a one-way clutch F1. A brake B2 is provided, and a second coast brake B1 is provided between the sun gear 61 and the housing Hu. This automatic transmission is equipped with a transmission section as described above, and is operated by a central processing unit that receives the outputs of a throttle sensor that detects the throttle opening that reflects the engine load condition, a vehicle speed sensor that detects vehicle speed, etc. The hydraulic control device is driven according to a preset shift pattern, and the clutches, brakes, etc. are engaged as shown in FIG. 5 to control the shift. By the way, in view of its function as an auxiliary transmission that can switch between a low gear and a high gear, such as the overdrive mechanism 4°, in recent years it has been actively synchronized with the shift of the main transmission.
There is a system in which a multi-speed shift of six forward speeds is achieved by shifting the main transmission and the sub-transmission simultaneously or alternately. This speed change υl111] is achieved by using a transmission similar to that described above, and by combining the brakes and clutches as shown in FIG. In addition, in the figure, X indicates a joint to be made when the engine brake is activated. This type of gear shift control is based on existing automatic transmissions, and allows for easier gear shifting with a larger number of gears, while requiring fewer design changes and being advantageous in manufacturing.
In addition to improving fuel efficiency and reducing shift shock, it also achieves good results in terms of equalizing the torque shared among each member of the transmission, and provides many benefits such as improving the durability of the friction material. can. By the way, line pressure has conventionally been generally used as the working oil pressure for each of the friction coupling devices. This line pressure replaces the basic oil pressure generated by the oil pump.
This is obtained as a result of the primary regulator valve automatically adjusting the pressure to match the vehicle speed and engine load (throttle opening) at that time, and the minimum necessary pressure is maintained even when the throttle is fully open to ensure smooth gear shifting 111a. The maximum pressure is controlled so that the required pressure can be obtained in all conditions, including when the throttle is fully open and when the maximum stall is applied. So-called cutback control is known as one type of this control. This is based on the fact that in low gears, the rotational speed is slow but the transmitted torque is large, and in high gears, the rotational speed is high but the transmitted torque is small, and by keeping the hydraulic pressure low in the high gears, the shift shock is reduced. At the same time, it is designed to reduce the power consumption of the oil pump system, and is generally equipped with a throttle valve to reduce the feed-in pressure and a cutback valve to control the throttle valve, and the line pressure is reduced in the second gear or higher. I'm trying to lower it.

[Problems to be solved by the invention]

However, in an automatic transmission in which such shift control is performed, when the cutback control is attempted at the second gear or higher, the pilot oil pressure of the cutback valve that controls the operation of the throttle valve is Problems have arisen in terms of security. That is, in the past, as is clear from the connection/assembly diagram in Figure 5, the second brake B2 was always engaged in the second gear or higher, so the hydraulic pressure to the second brake B2 was cut back. It was possible to configure it to be used as pilot oil pressure for the valve. However, if the overdrive mechanism 40 is used as an auxiliary transmission,
In an automatic transmission that actively synchronizes this with the main transmission, which is the underdrive mechanism 6o, and shifts the main transmission and the auxiliary transmission simultaneously or alternately, multi-speed shifting is achieved. As is clear from the connection/combination diagram in Figure 6, the second brake B2 is only engaged at 3rd gear or higher, and other brakes and clutches are only engaged at 1st gear. (Those that do not engage, and engage at all gears from 2nd gear onwards; those that generate hydraulic pressure)
This caused the problem that there was no such thing. If the cutback is performed only in the third gear or above, not only will there be more power loss than necessary in the second gear, but also the friction coupling device will suffer when shifting from the first gear to the second gear. The working pressure increases and may cause a large shift shock.

[Object of the Invention] The present invention has been made in view of the above-mentioned problems, and the present invention has been made in such a way that the transmission is not engaged in the first gear, but is engaged in all gears from the second gear onwards. An object of the present invention is to provide a hydraulic control device for an automatic transmission that can perform cutback control at all gears higher than the second gear even in an automatic transmission without a brake or clutch. [Means for Solving the Problems 1] The present invention includes a throttle valve for reducing line pressure and a cutback valve for controlling the throttle valve, and also changes the gear position in relation to at least vehicle speed and throttle opening. Hydraulic control of an automatic transmission that does not have a friction coupling device that does not engage in the first gear and is engaged in all gears from the second gear onwards, as a friction coupling device that automatically switches. In the device, an oil passage group consisting of two or more oil passages in which hydraulic pressure is generated at a gear stage other than the first gear stage, and at least one oil passage in every gear stage other than the first gear stage. In addition to setting a combination of oil passages that generate hydraulic pressure,
The above object is achieved by using the oil pressure generated in the oil passages constituting the oil passage group as the pilot oil pressure for the cutback valve that controls the throttle valve. [Function] In the present invention, the oil passage is composed of two or more oil passages excluding the oil passage in which oil pressure is generated in gears other than the first gear, that is, the oil passage in which oil pressure is generated in the first gear, and A group of oil passages is appropriately set such that oil pressure is generated in at least one oil passage in all gears other than the first gear, and the oil pressure generated in the oil passages constituting the group of oil passages is set as described above. Since the pilot oil pressure is used for the cutback valve that controls the throttle valve, high line pressure can be obtained in the first gear, and line pressure can be kept low in all the gears from the second gear onwards.

【Example】

Embodiments of the present invention will be described in detail below based on the drawings. In this embodiment, the oil passage group is composed of two or more oil passages in which hydraulic pressure is generated in gears other than the first gear, and at least one oil passage is generated in all the gears other than the first gear. An oil path group consisting of a combination of an oil path to the overdrive brake Be and an oil path to the second brake B2 was selected as a combination of oil paths such that oil pressure is generated in two oil paths. In other words, these two oil passages are connected at gears other than the first gear, that is, they are oil passages in which no hydraulic pressure is generated in the first gear, and all oil passages in the second gear and above are connected. 2 in gear
Since one of the two oil passages is in a joint state,
This is because the conditions for the oil passage group are satisfied. As is clear from the above explanation, it goes without saying that the names of overdrive brake BOX and second brake B2 do not mean overdrive or a brake that is engaged in the second gear. FIG. 2 shows an outline of an embodiment of a hydraulic control device to which the present invention is applied, and FIG. 1 shows the main parts corresponding to the broken line in FIG. 2. In the figure, reference numeral 100 is a cutback valve. Each of these cutback valves 1oO has a different face surface IA.
+, Az, A3 (Aa<At<Az) rounds 102.104.106. Control ports 110, 112 of cutback valve 100
, oil passages 3 branched from oil passages 300 and 302 to the second brake B2 and overdrive brake Bo, respectively.
04.306 is connected. Also, boat 114.11
6 is connected to an oil passage 310 branched from an oil passage 308 from the throttle valve 200. Further, the boat 118 is connected to the boat 20 of the throttle valve 200 via the oil passage 312.
It is connected to 2. Boat iii when hydraulic pressure is applied to second brake B 2 and overdrive brake Bo. The oil pressure applied to 112 is line pressure PL. For convenience, these are referred to as Pez and Pso. Also, boat 11
The oil pressure applied to 4.116 is throttle pressure PTH. The land faces AI, A2, and A3 are set so that the following equation holds true over the entire throttle opening range. 8th 2°As >PTI-10Az Pea (Az-As>>Pv+-Az-(1) Next,
To explain the operation of this embodiment, the cutback valve 100
The balance of the forces acting on the spool 108 is as follows: (2) for the downward force and (3) for the upward force. 8th day 2 ・A 1+ Pso(Az-As)...(
2) (A2-A3)PTH+A3 ・PTH...(
3) The first term of the upward force (A2''A3)・PTH is zero at the upper end position of the valve shown on the left side of the figure, so the upward force at this time is A3・PTH. A'2 '> A s Therefore, the upward force becomes maximum at A2·PTH at the lower end position of the valve.On the other hand, since the face area of the spool 108 of the cutback valve 100 is set to the relationship shown in equation (1) above, the boat 110 When 8 days 2, P days O acts on one or both of 112, the spool 108
is sure to move to the lower end, boats 114 and 118 are short-circuited, and the boat 2 of the throttle valve 200 is connected via the oil passage 312.
Throttle pressure PTH acts on 02. In the throttle valve 200, a cutback effect is performed by the throttle pressure PTH from the boat 202. This action itself is exactly the same as that of a normal throttle valve. That is, to explain briefly, the balance equation of the spool 204 of the throttle valve 200 is expressed by the following equation. PTH(A2-A-a)-Fs・=(4)PTI-1(
A2 As>=Fs (5) Here, Fs is the urging force of the spring 206, and A2 to A4 are the face areas of the lands 210 to 212 of the spool 204. Therefore,
At the same throttle opening (when the rotation angle of the throttle cam 208 is the same), when the throttle pressure PTH acts on the boat 202 of the throttle valve 200, the throttle pressure P
TH is low and becomes high when it is not working. As a result, when oil pressure is generated in at least one of the oil passages to the second brake B 2 and the overdrive brake Bo, the throttle pressure PTH is output from the boat 118 of the cutback valve 100. The throttle pressure PTH can be kept low at all gears higher than the second gear except for the first gear. The configuration and operation of the hydraulic control device shown in FIG. 2 other than the part surrounded by the broken line are the same as those of the conventional system, so a detailed explanation will be omitted.
The boat 402 of the primary regulator valve 400 is connected to the boat 402 of the primary regulator valve 400 via an oil passage 314 branched from the oil passage 314, and the accumulator control valve 5 is connected to the boat 402 of the primary regulator valve 400 via an oil passage 316 branched from the oil passage 314.
00 boat 502. The primary regulator valve 4001 and the accumulator control valve 500 receive the input of the throttle pressure PTH, and by a well-known action, when the throttle pressure PTH is large, the line pressure PL is high.
Also, the high accumulator back pressure Ps is regulated (PL=Pa above a certain throttle opening). Therefore, by performing the cutback, the throttle pressure 1H can be reduced, and the line pressure P L s and the accumulator back pressure Ps can be reduced accordingly. In addition, in FIG. 2, reference numeral 550 is an oil pump, and 6
00 is a manual valve that is operated according to the shift lever operated by the driver, 700A to 700C are shift valves that are respectively driven by solenoid valves 800A to 800C, and 90
0A to 900C respectively indicate accumulators that control the rise characteristics of the hydraulic pressure toward the friction coupling device. FIG. 3 shows the shift transient characteristics when shifting from the first gear to the second gear. As shown in Fig. 6, the shift from the first gear to the second gear is achieved by engaging the overdrive brake Bo, but in the conventional circuit, a cutback is achieved by the working pressure of the second brake B2. valve 10
0, cutback is not effective in 2nd gear, throttle pressure PTI-1 is high, and line pressure PTI-1 is high.
It can be seen that the Ls accumulator control pressure P is also high, and the oil pressure level when the accumulator is in operation is high as shown in the figure, leading to worsening of the shift shock. It can also be seen that in the second gear state, the line pressure is high, which causes unnecessary power loss due to the oil pump. In the above embodiment, as the shift valve 700C is switched immediately after the shift command (time a), the cutback valve 100C is switched.
The oil pressure of the control boat 112 increases as shown by the dashed line,
A cutback corresponding to the predetermined amount ΔPL is performed. At the same time, accumulator pressure distribution f? Since e is also low (pressure regulated), the hydraulic pressure Peo of the overdrive brake when the accumulator is activated [I (area X in Figure 3) can be lowered by ΔPao, and the shift shock can be reduced by that much. When a gear shift is performed, as shown in Fig. 6, the overdrive brake hydraulic pressure is drained in, for example, 3rd and 5th gears, but in 2nd gear or higher, either the overdrive brake So or the second brake B2 is always used. As a result, cutback is performed at all gears from the second gear onwards, which reduces gear shift shock and prevents unnecessary power loss.In the above embodiment, adopted an oil path group consisting of a combination of an overdrive brake B o 1 and a second brake B2, but the oil paths constituting the oil path group in the present invention are limited to this combination. The key point is that it is composed of two or more oil passages in which oil pressure is generated in gears other than the first gear, and that at least one oil passage is supplied with oil pressure in all gears other than the first gear. In addition, in the above embodiment, the cutback valve 1oO is provided with three lands having different face areas, but in the present invention, the cutback valve The configuration of 100 is not limited to this example, and the key point is that the oil passages forming the oil passage group do not interfere with each other, and when hydraulic pressure is generated in any of the oil passages, the cutback valve is activated. is a thrower. Any configuration is sufficient as long as it acts on the torque valve in the direction of reducing line pressure.In some cases, the cutback valve may be the same as the conventional one, and a check valve or the like may be added to the input side of the cutback valve. Further, in the above embodiment, an automatic transmission is shown which is equipped with a main transmission and an eleventh transmission, and which shifts these at the same time or alternately to achieve multi-speed transmission. Transmissions are not limited to these types, but include automatic transmissions that do not engage in the first gear and do not have a friction coupling device that engages in all gears from the second gear onwards. Applicable to any occasion.

【Effect of the invention】

As explained above, according to the present invention, in any automatic transmission related to any coupling/combination, cutback is performed in all gears from the second gear onwards, thereby reducing shift shock and preventing oil pump failure. An excellent effect can be obtained in that necessary assistance consumption can be prevented.

[Brief explanation of drawings]

FIG. 1 is a hydraulic circuit diagram showing the main parts of a hydraulic control device for an automatic transmission to which the present invention is applied, and FIG. i
FIG. 3 is a shift transient characteristic diagram when shifting from the first gear to the second gear; FIG. 4 is a skeleton diagram showing an example of the transmission section of a conventional automatic transmission; FIG. 5 is a phase diagram showing an example of the engaged/combined state of each brake and clutch of the transmission section, and FIG. 6 is a diagram showing another example. So... Overdrive brake, B2... Second brake, 100... Cutback valve, 200... Throttle valve, 400... Primary regulator valve, 550...
oil pump.

Claims (1)

[Claims] (1) A friction coupling device that is equipped with a throttle valve for controlling line pressure and a cutback valve that controls the throttle valve, and that automatically switches gears in relation to at least vehicle speed and throttle opening. In a hydraulic control system for an automatic transmission that does not have a friction coupling device that does not engage in the first gear and is engaged in all gears from the second gear onwards, A group of oil passages consisting of two or more oil passages in which hydraulic pressure is generated, and a combination of oil passages in which hydraulic pressure is generated in at least one oil passage in all gears other than the first gear. A hydraulic control device for an automatic transmission, characterized in that a group is set, and the hydraulic pressure generated in the oil passages constituting the oil passage group is used as a pilot oil pressure of a cutback valve that controls the throttle valve.