JPS61105339A - Shift valve for automatic transmission - Google Patents

Abstract

PURPOSE:To make any perplexity in accerator operation avoidable without maximizing a shift valve, by letting down-shift hold pressure act on both pressure receiving surfaces and kick down pressure on one side of these surfaces alone. CONSTITUTION:When kick down pressure PKD is produced because of a kick down range, pressure acts on a pressure receiving surface 1b alone via a circuit 7 from a circuit 9. This pressure receiving surface, in its pressure receiving area, is smaller than that of governor pressure PG so that a spool 1 performs its down shift only at a kick down range below a car speed V1 with a shift line. Therefore, if accelerator opening is set to the kick down range at a high car speed range over the car speed V1, no down shift is performed whereby a fear of perplexing a driver because of unexpected sudden acceleration is eliminable and, what is more, the elongation of a shift valve is prevented, thus a layout is simplifiable in consequence.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a shift valve that controls speed change control of an automatic transmission.

(Prior Art) Automatic transmissions usually determine the gear position depending on the accelerator opening (engine load) and single transmission, and are equipped with various shift valves for this purpose. These shift valves basically have a sub-/I/ that receives the throttle pressure, which increases as the accelerator opening increases, and the governor pressure, which increases as the vehicle speed increases, in opposing directions, and the spool decreases due to the relationship between both pressures. It is configured to select a predetermined gear depending on whether the shift position is reached or the upshift position is reached.

In addition, the shift valve's spool pressure (line pressure, which is the highest pressure in an automatic transmission) generated at the kickdown pressure near the maximum accelerator opening is applied to counteract the governor pressure in the kickdown range. By stroking the spool to a downshift position, the automatic transmission is downshifted to a gear position below IG, thereby providing sufficient acceleration force.

By the way, among these shift valves, those that change gears at the high-speed shift crotch are also overdrive (
OD) Prohibited pressure, ■ Range pressure, or Range pressure (Izun
It is designed to act on the spool to counter the downshift hold pressure P governor pressure such as automatic transmission line pressure), and when the driver turns on the ODa stop switch to issue an OD prohibition command, or when an automatic transmission manual is issued. Fixed valve in 2nd gear f
When the manual valve is placed in the 1st gear fixed (I) range, by keeping the spool in the downshift position, the shift valve shifts the automatic transmission to the highest gear (overdrive). ) Avoid leaving yourself in a state of choice.

Conventionally, this type of shift valve has been developed by the applicant of the present invention.
"Automatic OD Transaxle RN Fake F02A Type RL4F02 & Type Maintenance Instructions" published in 841
There is a 3-4 shift valve inside.

This (7) 3-41 shift valve is as shown in Figure 3.
A spool 1 is provided, and a plug 8 is attached to the upper end of the spool 1 via a spring 2.
The lower end of the spool 1 in the figure faces the chamber 41 to which the governor/pressure PG is supplied, and the end face of the plug 8 farthest from the spool 1 faces the chamber 5 to which the throttle pressure PTH is supplied.
Let's face it. The chamber 6 created between the spool 1 and the plug 3 is connected to the outlet port of the shuttle valve 8 via a circuit 7, and the kickdown pressure PKD is applied to both robots of the shuttle valve 8, respectively.
circuit 9 for downshift hold pressure PH and circuit 1 for downshift hold pressure PH
Connect 0. A pressure receiving surface 1a is set on the spool 1, and the shuttle valve output pressure from a circuit 11 branched from the circuit 7 is applied to this pressure receiving surface 1a at an amplifier shift position shown in the left half of the spool 1 in the figure.

A force Ft due to the throttle pressure PTH acts on the spool 1 downward in the drawing via the spring force Fs of the spring 2, and a force FG due to the governor pressure PG acts on the spool 1 downward in the drawing.

F <, F (however, in the case of F ) or FG
<FtGS at (However, when F8<Ft, the spool l is at the downshift position shown in the right half of the figure, and the low clutch pressure (P
) The circuit 12 is connected to the line pressure (PL) circuit 18 to make the low clutch pressure P the same as the line pressure PL, so that the pressure P.

The low clutch operated by
Set to quick selection mode.

As the vehicle speed increases, the governor pressure PG increases, and FG>F6(Fs>
Ft) or F. >Ft (when Fs<Ft), the spool 1 is in the upshift position shown in the left half of the figure, and is passed through the drain circuit 1 of circuit 12B to bring the low clutch pressure P0 to zero, releasing the g-clutch. The automatic transmission is placed in the continuous selection state.

When the accelerator opening is brought close to the opening position in this -th speed signal selection state, kickdown pressure PKD is generated and this is applied to circuit 7'5.
: The pressure reaches the chamber 6 through the circuit 11 and the pressure receiving surface 1a.

At this time, since the kickdown pressure PKD is a high value equivalent to the line pressure PL, the spool 1 is connected to the governor FF, PG (
The automatic transmission is shifted down from the 4th gear to the 8th gear regardless of the vehicle speed, and sufficient acceleration force is obtained.

Also, when an OD prohibition command is issued, when a range is selected, or when an range is selected, a high hold pressure PH equivalent to the line pressure generated at this time reaches the chamber 6 and the pressure receiving surface 1a, keeping the spool l at the downshift position. To prevent an automatic transmission from entering a first mountain speed selection state.

However, in such a shift valve, the kickdown pressure PK
Pressure-receiving area of spool 1 on which D acts and hold pressure PH
Since the pressure receiving area of spool 1 that acts on is the same,
The pressure receiving area for the kickdown pressure PKD is too large, and the shift pattern becomes as shown in Figure 5, causing the kickdown pressure PKD to become too large.
In the kickdown range where D occurs, the automatic transmission downshifts from 41'FA to 8th gear regardless of the vehicle speed, resulting in the following drawbacks.

In other words, during high-load operation with the accelerator opening at a large opening just before the kick-down range, the driver may inadvertently press the accelerator pedal further due to running over a bump in the road surface, changing the driving posture, etc. When the accelerator opening degree is increased to the kick-down range by pressing down, the shift valve shifts the automatic transmission down as described above, regardless of the vehicle speed. In this case, the driver may be confused by sudden sudden acceleration or engine braking, resulting in a very dangerous situation.

Therefore, conventionally, the Porg Warner 45 type automatic transmission was equipped with the 41st
An 8-1 shift valve as shown was used.

This shift valve causes the kickdown pressure PKD to act on the spool 1 only in the chamber 6, and makes the pressure receiving area smaller than the area between the pressure receiving surfaces of the governor pressure PG, and the hold pressure PH is brought into contact with the plug 3 in the chamber 5. The mf governor pressure P is applied to another plug 15 on its pressure receiving surface. This is larger than the pressure receiving area of . In this case, the effect of the shift valve due to the hold pressure Pa is as described above with reference to FIG. At V□ or higher, downshifting will not occur even in the kickdown range. Therefore, even if the accelerator opening is inadvertently increased in the high vehicle speed range, the automatic transmission will not downshift, thereby avoiding the risk of driver confusion due to sudden sudden acceleration or engine braking.

(Problem to be solved by the invention) However, in this shift valve, since another plug 15 is added coaxially to the sprue/I/1, the axial dimension inevitably increases, and the current shift valve Even the valve is difficult to assemble into the valve body due to space constraints! , L, it is inevitable that the valve body will be larger. Also, does the separate plug 15 increase the number of parts? This also increases the number of assembly steps, which contributes to making automatic transmissions more expensive.

(Means for Solving the Problems) In view of the above points, the present invention has developed a shift valve that can achieve the above objectives without adding any separate parts, and has a spool with downshift hold pressure and kick. It is characterized by having a pressure receiving surface that commonly receives down pressure and a pressure receiving surface that receives only downshift hold pressure.

(Function) In this configuration, the downshift hold pressure acts on both of the pressure receiving surfaces to ensure that the spool is in the downshift position. However, one kickdown pressure acts only on one corresponding pressure receiving surface, and the downshift position cannot be achieved at a vehicle speed higher than that of the spool P, and the same effect as described in item σ can be achieved.

Since this function and effect are achieved without the need for any additional new parts, the shift valve can be prevented from becoming long and its layout is easy, and the number of parts and assembly man-hours do not increase. This will contribute to lower prices.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 shows an inverted version of the shift valve of the present invention, in which the same parts as in FIG. 8 are designated by the same reference numerals.

In this example, 50 boats of shuttle valve 8 are connected to chamber 6 by circuit 7, while circuit 11 is connected to hold pressure circuit 10. The spool 1 has a pressure receiving surface 1b which commonly receives the output pressure of the shuttle valve 8, that is, the downshift hold pressure PH and the kickdown pressure PKD, in the chamber 6, and sets this as the governor pressure P. be smaller than the pressure receiving surface. Further, the downshift hold pressure P from the circuit 11 is applied to the pressure receiving surface 1a.
Only H acts on the pressure receiving surface 1a and the pressure receiving surface 1.
The sum of the pressure receiving areas with b and b is made larger than the pressure receiving area of governor pressure PG.

In the above configuration, during driving in which downshift bold pressure PH and kickdown pressure ``KD'' do not occur, that is, automatic transmission driving CD), normal driving in which ○D is not prohibited (accelerator opening is changed to outside the kickdown range) While driving at a small or medium opening, the spool 1 shifts to a downshift position in the right half of the figure or an upshift position in the left half of the figure, depending on the relative relationship between the throttle pressure "TH" and the governor pressure PG, as described above with reference to FIG. position, and a low speed gear other than the first gear or a second gear is set to the magnetic plate.

■ Range selection, I range selection, or D-ring 2
If downshift hold pressure PH is generated by turning on the selected OD prohibition switch, this pressure will be applied to circuit 1o.
On the other hand, circuit 11? It acts on the pressure receiving surface 1a via the shuttle valve 8 and the circuit 7 depending on how it is used, and also on the pressure receiving surface 1b. Pressure receiving surface 1. The sum of the pressure receiving areas of a, 1b is the governor pressure P. Since the spool 1 is larger than the pressure receiving area of , the spool 1 is held at the downshift position in the right half of the figure, and prevents the automatic transmission from entering the 41st gear selection state.

When the kickdown pressure "KD" is generated in the kickdown region, this pressure passes through the circuit 7 and acts only on the pressure receiving surface 1b.By the way, the pressure receiving surface area of this pressure receiving surface is larger than the pressure receiving area of the governor pressure PG. Because of its small size, the spool 1 acts in the same manner as described above with reference to Fig. 4, and downshifts only in the kickdown range below the vehicle speed v1 using the shift line shown in Fig. 2.For this reason, in the high vehicle speed range above the vehicle speed V0 Even if the driver inadvertently shifts the accelerator opening to the kick-down range, no downshift is performed, thereby eliminating the risk of confusion for the driver due to sudden sudden acceleration or engine braking.

(Effects of the Invention) In the present invention, the spool 1 is equipped with downshift hold pressure PH and kickdown FE without adding any separate parts to achieve such effects.
Both sides of PKD? Since the configuration has the pressure receiving pressure ff1lb to be received and the pressure receiving surface 1a receiving only the downshift hold pressure PH, it is possible to prevent the shift valve from increasing in length, simplifying its layout, and increasing the number of parts and assembly work. Since there is no automatic transmission, it is possible to achieve a low-cost automatic transmission.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the shift valve of the present invention, FIG. 2 is a shift diagram using the same shift valve, and FIGS. 3 and 4 are sectional views showing two examples of conventional shift valves, respectively. FIG. 5 is a shift diagram using the shift valve shown in FIG. 3. 1... Spool 1a... Downshift hold pressure pressure receiving surface 11)...
Downshift hold crimp kickdown pressure pressure receiving surface 2...Spring 8...Plug 41-6.
...Chamber 8...Shuttle valve 9...Kickdown pressure circuit 10...Downshift hold pressure °12...Low clutch pressure circuit 18...Line pressure path 1 sound...Drain circuit Patent applicant Nissan Motor Co., Ltd. Figure 1

Claims (1)

[Claims] 1. A spool that receives throttle pressure and governor pressure facing each other and strokes between a downshift position and an upshift position, and a downshift hold so that the spool faces the governor pressure. In the shift valve of an automatic transmission, the shift valve is stroked to the downshift position when selectively receiving pressure or kickdown pressure, and the spool includes a pressure receiving surface that commonly receives the downshift hold pressure and the kickdown pressure. and a pressure receiving surface that receives only the downshift hold pressure.