JPH0475413B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to a shift device for an automatic transmission.

(B) Prior Art A conventional shift valve used as a shift device for an automatic transmission applies a governor pressure corresponding to the vehicle speed and a throttle corresponding pressure corresponding to the throttle opening of the engine in opposing directions on the spool. It is designed to switch depending on the balance of both hydraulic pressures (for example, Japanese Patent Application Laid-Open No. 55-47037 and "Nitsun Automatic Transmission, L4N71B").
Type, E4N71B type, 1982 maintenance manual (November 1982)
1-2 shift valve shown on page 74 of "Published by Nissan Motor Co., Ltd."). In order to prevent hunting of the shift valve, there is a difference between the hydraulic pressure balance during upshifting and the hydraulic pressure balance during downshifting. That is, hysteresis is provided in the shift line. Hysteresis is provided, for example, by changing the pressure receiving area on which the throttle corresponding pressure acts between the down position and the up position of the valve. However, such conventional shift valves have a problem in that the greater the throttle corresponding pressure, the greater the hysteresis, making it impossible to obtain a desired shift line. In other words, for example, if sufficient hysteresis is provided to prevent hunting at low throttle openings, the hysteresis at high throttle openings will become too large, and downshifts will not occur even if the throttle opening is increased at relatively high vehicle speeds. It had become commonplace. In order to improve the above problem, as shown in Japanese Patent Application Laid-Open No. 57-144338, in addition to the 2-3 shift valve for shifting from 2nd to 3rd speed, a 3-2 down shift valve exclusively for downshifting was proposed. Some are equipped with a shift valve. 3-2 The downshift valve has a structure in which the force from the governor pressure, the opposing force from the spring, and the force from the throttle modulator pressure act on the spool, and the spool absorbs these three forces. Move by balance. That is, when the force due to the governor pressure is greater than the force due to the spring force and the force due to the throttle modulator pressure, the spool is in the up position, and when it is smaller, the spool is in the down position. Further, when the spool is in the down position, the throttle modulator pressure acting on the 3-2 downshift valve also acts on the 2-3 shift valve. Downshifting is performed as follows. The spool of the 3-2 downshift valve in the up position is moved to the down position by increasing the throttle opening and applying a large throttle modulator pressure. As a result, the throttle modulator pressure acts on the 2-3 shift valve, and the spool is forcibly switched to the down position.
A downshift is performed. This makes it possible to set the upshift shift line and downshift shift line independently, so it is possible to adjust hysteresis to a certain extent, but it is possible to adjust the hysteresis to a certain extent, but it is possible to adjust the hysteresis to a certain extent by changing the slope of both shift lines to an extreme degree, which will result in a high throttle opening. It was not possible to significantly reduce the hysteresis on the power side.

Furthermore, as shown in Japanese Patent Application Laid-Open No. 52-109078, some gears are equipped with a switching valve that can control the timing of gear changes. The switching valve shown here has governor pressure acting on one end of the spool, and a spring that applies a force in the opposite direction to the governor pressure on the other end. A first switching valve that moves the spool depending on the balance with the force and outputs governor pressure to a second switching valve (described later), and a throttle-compatible pressure acts on one end of the spool, and a throttle-compatible pressure acts on the other end. A spring is provided that applies a force in a direction that opposes the pressure, and the spool is moved by the balance between the force due to the throttle corresponding pressure and the force of the spring, and the governor pressure output from the governor valve or the first switching valve is The second
It consists of a switching valve. By changing the governor pressure acting on the 2-3 shift valve with the first switching valve and the second switching valve, the 2-3 shift valve and the timing of gear change are controlled, and upshift characteristics and downshift characteristics are changed. be able to. However, this
This method is intended to obtain gear shifting characteristics at low vehicle speeds that are preferable in terms of exhaust emissions, and although it is possible to reduce the hysteresis on the low throttle opening side, it is not possible to reduce the hysteresis on the high throttle opening side.

The shift line of an automatic transmission must be set according to the specifications of the vehicle and engine, and it is preferable that the hysteresis at each throttle opening can be set as desired. However, in conventional automatic transmission shift devices, the above It was not possible to set the hysteresis as desired.

(c) Purpose of the Invention The object of the present invention is to provide a shift device for an automatic transmission that can set a desired shift line by increasing hysteresis at low throttle openings and decreasing hysteresis at large throttle openings. It is said that

(d) Structure of the Invention The shift device for an automatic transmission according to the present invention includes a shift valve and a downshift valve in which a governor pressure corresponding to the vehicle speed and a throttle corresponding pressure corresponding to the throttle opening of the engine are applied in opposing directions. The shift valve can switch between supplying and cutting off hydraulic pressure to the friction element, and the downshift valve has a mechanism in which the force from the side where the throttle corresponding pressure acts is greater than the force from the side where the governor pressure acts. When the shift valve becomes tired, it is possible to forcefully switch the shift valve to the down position by applying a predetermined hydraulic pressure to the shift valve.
The shift valve is provided with a spring that applies a force in a direction that opposes the governor pressure, and the downshift valve is provided with a spring that applies a force in a direction that opposes the throttle corresponding pressure.

(e) Embodiments Examples of the present invention will be described below with reference to FIGS. 1 to 4 of the accompanying drawings.

FIG. 1 shows a schematic diagram of the power transmission mechanism of an automatic transmission with three forward speeds and one reverse speed. This power transmission mechanism includes an input shaft I to which rotational force from an engine output shaft E is transmitted via a torque converter T/C, an output shaft O to transmit driving force to a final drive device, a first planetary gear set G 1 , a first planetary gear set G 1 , and a first planetary gear set G ₁ . It has two planetary gear sets _G2 , a high and reverse clutch H&R/C, a forward clutch F/C, a band brake B, a low and reverse brake L&R/B, and a one-way clutch OWC. 1st planetary gear set G ₁
is sun gear S ₁ , internal gear R ₁ , and pinion gear P ₁ that meshes with both gears S ₁ and R ₁ at the same time.
It consists of a carrier PC that supports ₁ and
Further, the planetary gear set _G2 is composed of a sun gear _S2 , an internal gear _R2 , and a carrier _PC2 that supports a pinion gear _P2 that meshes with both gears _S2 and _R2 at the same time. Each component is connected as shown. The above power transmission mechanism includes a high and reverse clutch H&R/C, a forward clutch F/C, a band brake B, and a low and reverse brake L&R/B (one-way clutch).
By operating the OWC) in various combinations, each element ( _{S 1} , S _{2 ,}
R ₁ , R ₂ , PC ₁ , and PC ₂ ) can be changed, thereby varying the rotational speed of the output shaft O relative to the rotational speed of the input shaft I to achieve three forward speeds and one reverse speed. Obtainable.

FIG. 2 shows a hydraulic control device according to the present invention. This hydraulic control device includes a regulator valve 1, a manual valve 2, 1-2, a shift valve 3, 2-3
Shift valve 4, 3-2 downshift valve 5,
Line pressure booster valve 6, pressure modifier valve 7, throttle valve 8, throttle fuel safety valve 9, throttle modulator valve 10, 1st speed fixed range pressure reducing valve 1
1, an accumulator 12, a 3-2 timing valve 14, a high and reverse clutch pressure reducing valve 15, and a governor valve 16, which are connected to the torque converter T/C, high and reverse clutch H&R/C, and forward clutch F/C.
C, servo apply chamber S/A and servo release chamber S/ that activate or deactivate band brake B;
R, low and reverse brake L&R/B, and oil pump O/P as shown in the figure. With this configuration, the high and reverse clutch H&R/C, the forward clutch F/C, and the low and reverse brake L&R are activated depending on the vehicle speed and engine throttle opening.
Hydraulic pressure is distributed to R/B, servo apply chamber S/A, and servo release chamber S/R as prescribed, but 2-3 shift valve 4 directly related to the present invention
The description of components other than the 3-2 downshift valve 5 will be omitted. The specific structure and operation of the parts whose explanations are omitted are described in Japanese Patent Application Laid-Open No. 144338/1983 filed by the present applicant.

Governor pressure is supplied to the port 20 of the 2-3 shift valve 4 from the governor valve 16 via the oil passage 22, and throttle corresponding pressure is supplied to the port 24 from the throttle modulator valve 10 via the oil passage 26. Supplied. Further, the port 28 of the 2-3 shift valve 4 communicates with the port 32 of the 3-2 downshift valve 5 via an oil passage 30. The spool 34 of the 2-3 shift valve 4 can be switched between a down position shown in the right half of the figure and an up position shown in the left half, and in the down position, communication between ports 36 and 38 is established. is blocked and ports 36 and 3 are connected in the up position.
8 communicates with each other. Line pressure is supplied to the port 36 from the manual valve 2 via an oil line 40, and the port 38 is connected via an oil line 42 to the servo release chamber S/R and the high and reverse clutch H&R/C. There is. The spool 34 of the 2-3 shift valve 4 is constantly receiving a downward force in the figure from the spring 44. The port 46 of the 3-2 downshift valve 5 is supplied with governor pressure from the oil passage 22, and the port 48 is supplied with the governor pressure from the oil passage 2.
Throttle corresponding pressure is supplied from 6. 3-
The port 32 of the 2-3 downshift valve 5 is connected to the port 28 of the 2-3 shift valve 4 via the oil passage 30 as described above, and the port 50 is connected to the oil passage 52. The oil passage 52 is drained in normal cases other than during kickdown. A spring 56 applies an upward force in the figure to the spool 54 of the 3-2 downshift valve 5.

Next, the operation of this embodiment will be explained. 2-
3 The spool 34 of the shift valve 4 receives the upward force due to the governor pressure acting on the port 20 and the spool 34 of the shift valve 4.
Depending on the balance between the force of the throttle corresponding pressure acting on the throttle valve 4 and the downward force of the spring 44, it is switched between the down position shown in the right half of the figure and the up position shown in the left half of the figure. As a result, the switching characteristics shown by the solid line in FIG. 3 are obtained.
Note that the reason why the intersection of the solid line with the horizontal axis is shifted from the origin by a distance a is because the force of the spring 44 acts on the solid line in this figure. Note that when the throttle corresponding pressure is supplied from the 3-2 downshift valve 5 to the port 28 via the oil passage 30, the spool 34 is placed in the down position regardless of the value of the governor pressure of the port 20. 3-2 The downshift valve 5 shifts to the right in the figure due to the balance between the upward force of the governor pressure acting on the port 46 and the force of the spring 56, and the downward force due to the throttle corresponding pressure acting on the port 48. Switches between a down position shown in the half and an up position shown in the left half. In the up position, port 32 is drained via port 50 and oil passage 52. For this reason, 2-
No throttle corresponding pressure is supplied to the port 28 of the three-shift valve 4, and the switching characteristics shown by the solid line in FIG. 3 described above are obtained. When the 3-2 downshift valve 5 is in the down position, the port 48 and the port 32 communicate with each other, and the throttle corresponding pressure in the oil passage 26 is transferred to the 2-3 shift valve 4 through the port 48, the port 32, and the oil passage 30. Acts on port 28. As mentioned above, when the throttle corresponding pressure is supplied to the port 28, the spool 34 of the 2-3 shift valve 4 is always switched to the down position. Therefore, the switching characteristics of the 2-3 shift valve 4 from the up position to the down position are determined by the switching characteristics of the 3-2 downshift valve 5 from the up position to the down position. The switching characteristics of the 3-2 downshift valve 5 are shown by the broken line in FIG. The reason why the intersection of the broken line with the vertical axis in FIG. 3 is shifted from the origin by an amount b is because the force of the spring 56 acts in the same direction as the force due to the governor pressure. As a result, by the action of the 2-3 shift valve 4 and the 3-2 downshift valve 5, a 2-3 upshift shift line shown by a solid line and a 3-2 downshift shift line shown by a broken line in FIG. 3 are obtained. That will happen. As is clear from Fig. 3, hysteresis (the same throttle response pressure)
The difference between the governor pressure during upshift and the governor pressure during downshift for P _TH is the throttle corresponding pressure.
It becomes smaller as P _TH increases. Third
If the horizontal axis of the figure, the governor pressure _PG , is replaced with the vehicle speed, and the vertical axis, the throttle corresponding pressure _PTH , is replaced with the throttle opening, the shift line becomes as shown in FIG. 4. Note that the reason why there is a perpendicular portion to the shift line is that the supply of governor pressure is cut off below a predetermined rotational speed. This fourth
As is clear from the figure, sufficient hysteresis is ensured at low throttle openings, where hunting is relatively likely to occur, and the downshift line is close to the upshift line in the region of large throttle openings, making the comparison Even at high speeds, downshifting can be achieved by increasing the throttle opening. Therefore, it is possible to set a preferable shift point according to the specifications of the vehicle and engine. Note that the hysteresis is caused by the spring 56 of the 3-2 downshift valve 5 and the 2-3
By changing the setting force of the spring 44 of the shift valve 4 (that is, by changing the values of b and a in FIG. 3), it can be easily changed within a predetermined range. Therefore, the desired 2-3 upshift shift line and 3-2 downshift shift line can be obtained.

(F) Effects of the Invention As explained above, the shift device according to the present invention has a shift valve (a shift valve ( The described embodiment has a 2-3 shift valve 4) and a downshift valve (3-2 downshift valve 5), and the shift valve has a predetermined friction element by switching between an up position and a down position. It is possible to switch between supplying and shutting off hydraulic pressure to the downshift valve, and when the force from the side where the throttle corresponding pressure acts is greater than the force from the side where the governor pressure acts, the downshift valve uses a predetermined hydraulic pressure to the shift valve. The shift valve is provided with a spring that applies a force in a direction that opposes the governor pressure, and the down shift valve is provided with a spring that applies a force in a direction that opposes the throttle corresponding pressure. Since a spring is provided that exerts a force of This makes it possible to obtain a desired shift line that prevents the occurrence of hunting at low vehicle speeds and allows downshifting at relatively high vehicle speeds.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an automatic transmission, FIG. 2 is a diagram showing a hydraulic control device having a shift device for an automatic transmission according to the present invention, and FIG. 3 is a diagram showing switching characteristics of a shift device for an automatic transmission according to the present invention. FIG. 4 is a diagram showing a shift line of a shift device of an automatic transmission according to the present invention. 4...2-3 shift valve, 5...3-2 downshift valve, 44...spring, 56...
spring.

Claims (1)

[Claims] 1. It has a shift valve and a downshift valve in which the governor pressure corresponding to the vehicle speed and the throttle corresponding pressure corresponding to the throttle opening of the engine are applied in opposite directions, and the shift valve is used to switch between the up position and the down position. Therefore, it is possible to switch between supplying and cutting off hydraulic pressure to a predetermined friction element, and the downshift valve operates at a predetermined level when the force from the side on which the throttle corresponding pressure acts becomes greater than the force on the side on which the governor pressure acts. The shift valve can be forcibly switched to the down position by applying hydraulic pressure to the shift valve, and the shift valve is equipped with a spring that applies a force in the direction that opposes the governor pressure. A shifting device for an automatic transmission that is provided with a spring that exerts a force in a direction that opposes the corresponding pressure.