JPS61165054A - Speed change shock absorber for automatic transmission - Google Patents

Abstract

PURPOSE:To reduce impact upon speed change by coupling an accumulator common to two friction elements to the downstream of an orifice. CONSTITUTION:Upon switching of a shift valve 3 from the condition shown on the lower half section of drawing to that shown on upper half section, the line pressure PL is fed through an orifice 8 in common circuit 4 to first friction element 1 as the fastening pressure Pc from the circuit 5 while fed as the releasing pressure PR from the circuit 6 into the release chamber 7a of a servo 7 thus to release the second friction element 2. Here, the accumulator 9 is shared by both elements 1, 2. During this up-shift speed change, the accumulator 9 will set new shelves alpha2, beta2 synchronized prior to the shelf alpha1 due to the servo stroke to the first and second friction element transmission torques. Consequently, speed change impact can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention applies line pressure to a first friction element through a common circuit with an orifice using a common shift valve as a fastening pressure.
The present invention also relates to a shift shock reduction device for an automatic transmission that engages the first friction element and releases the first friction element to perform upshifts and speeds by supplying release pressure to the second friction elements. be.

(Prior art) This type of automatic transmission has been manufactured by Nichijo Jidosha Co., Ltd. 19
Published in September 1976 “Nissan Fluo → Tf Tsuku 8N71B
The one shown in Figure 3, which is described in the "Mold Maintenance Manual", is known. This automatic transmission has a front clutch 1 as a first friction element, a band brake 2 as a second friction element, and a 2-8 shift valve 8 as a common shift valve. shift valve 3
When the line pressure PL is in the upper half state in the figure due to the presence of the 8th speed pressure P8, the line pressure PL is passed through the common circuit 4 and the engagement pressure circuit 5 to the engagement pressure P. At the same time, line pressure is also supplied to the servo release chamber 7a of the servo 7 for the band brake 2 as the release pressure PR via the common circuit 4 and the release pressure circuit 6. Fastening pressure P. is front clutch 1
Even if the servo apply chamber PA (same value as the line pressure "L") is supplied to the servo apply chamber 7b of the servo 7, the release pressure PR will be applied to the servo piston 7 due to the pressure receiving area.
Move c to the right in the figure to release the band brake 2. Thus, the automatic transmission selects the third speed by engaging the front clutch 1 and releasing the band brake 2.

When the shift valve 8 is in the lower half state in the figure due to a decrease in the 8th speed pressure P8, the common circuit 4 is connected to Dorenbo (Drenboe) 3a, and eliminates the engagement pressure P0 of the front clutch 1 and the release pressure PR of the band brake 2. . As a result, the front clutch is released and the band brake 2 is engaged by the servo apply pressure PA via the servo piston 7C, so that the automatic transmission selects the second speed.

(Points to be solved by the invention) By the way, in the automatic transmission described above, the shift valve 3 switches from the lower half state in the figure to the upper half state in the figure, and shifts from the second gear to the third gear. An orifice 8 is provided in the common circuit 4 so that the engagement of the front clutch 1 and the release of the band brake 2 are synchronized when an upshift is performed. Figure 4 (,
As shown in a), and as shown in Fig. 4(b) at high throttle opening.
Because this was done at such a slow rate, it caused the opening described below.

That is, under a low throttle opening, at instant t□ in FIG. 4('a), the band brake 2 is suddenly released in response to the engagement of the front clutch 1, and the engine starts racing as shown by ΔN. By setting the output shaft torque waveform of an automatic transmission to have a peak torque ΔT, it was impossible to avoid a shift shock from occurring.

On the other hand, under high throttle opening, the 41st ffl (1)
) At instant t, the release of the band brake 2 is delayed with respect to the engagement of the front clutch 1, and the automatic transmission's intermittent pulls in the torque shown by ΔT2, and the shelf α of the front clutch transmission torque is lower than the band brake 2. Coupled with the fact that the length cannot be increased because the length is determined by the brake stroke, the shift shock shown by ΔT8 was inevitable to occur in this case as well. Furthermore, in this case, the engine speed changes rapidly, causing the above-mentioned shift shock to become large.

In addition, the height of the shelf of the front clutch transmission torque is determined by the servo piston 7C, causing the problem that there is no degree of freedom in design. In order to solve these problems, in the automatic transmission of the above type, an accumulator common to both friction elements is connected downstream of the orifice.

(Function) A new shelf synchronized with the previous shelf is generated, and by these new shelves, it is possible to prevent racing at low throttle openings and reduce the accompanying shift shock. This makes it possible to prevent the torque from being pulled in and reduce the shift shock that accompanies this.

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

FIG. 1 shows an example in which the idea of the present invention is applied to the automatic transmission shown in FIG. 3, in which the same parts as in FIG. 8 are designated by the same reference numerals.

In the present invention, an accumulator 9 common to both friction elements 1, 2 is provided downstream of the orifice 8. This accumulator includes a stepped piston 9a, an accumulator case 9b in which the stepped piston 9a is slidably fitted, and a stepped piston 9.
a and a spring 9C which is elastic at the right half position in the figure.

Then, the accumulator back pressure PB is introduced into the chamber 9d between both ends of the stepped piston 9a, and the chamber 9e facing the large diameter end of the stepped piston 9a is connected to the fastening pressure circuit 5.

In this configuration, when the shift valve 3 is switched from the lower half state in the figure to the lower half state in the figure, the line pressure "L" is increased from the circuit 5 via the orifice 8 in the common circuit 4 to the tightening pressure P.
. is supplied to the first friction element 1 to tighten it, and on the other hand, the release pressure PR from the circuit 6 causes an upshift from 2nd to 3rd speed by tightening the friction element 1 and releasing the second friction element 2. It is possible to change gears.

During this upshift, the accumulator 9 is at engagement pressure P.

and the release pressure PR, these pressures are increased as shown in FIG. Therefore, a new shelf α2 synchronized before the shield α1 accompanying the servo stroke is applied to both the first II friction element transmission torque and the second friction element transmission torque. β2 is set respectively.

The shelf α of the first jliI friction element transmission torque is shown in Fig. 2(a).
It is possible to eliminate the peak of the inertia phase at all throttle openings, and to make the change in engine speed gradual, regardless of whether the throttle opening is low as shown in Figure (b) or at a high throttle opening as shown in Figure (b). Contributes to reducing shock.

The shelf β2 of the second friction element transmission torque applies a slight residual torque to the second friction element 2 at low throttle opening as shown in FIG. As is clear from the output shaft torque waveform, it is possible to prevent this and reduce the accompanying shift shock.

Further, the shelf β2 of the second friction element transmission torque at high throttle opening shown in FIG. 2(b) is the shelf α of the first friction element transmission torque.
, by preventing interlock of the automatic transmission, it is possible to prevent torque pull-in as is clear from the output shaft torque waveform. In addition, since the shelf β2 can be lengthened freely, the upshift can be completed while the shelf is present, and the above-mentioned torque pull can be completely eliminated, and the shift shock caused by this can be reduced. In addition, shelf α2. Since the height of β2 can also be determined by changing the accumulator 9, the automatic transmission has a high degree of freedom in design and is convenient in that it is not limited to applicable vehicle types.

(Effects of the Invention) As described above, the device of the present invention has a configuration in which the accumulator 9, which is common to the first and second friction elements 1.2, is connected downstream of the orifice 8. , a new shelf α3 synchronized with the transmission torque of 2. β, can be set, and these shelves can prevent racing at low throttle openings and reduce the shift shock that accompanies this, as well as prevent damage to torque at high throttle openings. Since the shift shock can be reduced, and the height of the shelf can be freely changed by the accumulator 9, the self-sustainability of the design can be increased.

[Brief explanation of the drawing]

FIG. 1 is a main part shift control hydraulic circuit diagram of an automatic transmission showing an embodiment of the shift shock reducing device of the present invention, and a second fffl (
a) and (b) are the same operation time charts, Fig. 3 is a main part shift control hydraulic circuit diagram of an automatic transmission to which the present invention device is applied, and Fig. 4 (a) and (b) are the same operation. This is a time chart. 1...First friction element 2...Second friction element °8
...Common shift valve 4. ...Common circuit 5...
Fastening pressure circuit 6... Release pressure circuit 7... Servo 8... Orifice 9... Accumulator 9a... Stepped piston 9b... Accumulator case 9C... Spring po,... Fastening pressure PR・・・
・Release pressure PA...Servo apply pressure PB
...Accumulator back pressure PL...Line pressure P,...8 speed pressure Patent applicant Nissan Motor Co., Ltd. Figure 4 (a) (b)

Claims (1)

[Claims] 1. By supplying line pressure to the first friction element as engagement pressure and to the second friction element as release pressure through a common circuit with an orifice using a common shift valve,
An automatic transmission for upshifting by engaging a first friction element and releasing a second friction element, characterized in that an accumulator common to both friction elements is connected downstream of the orifice. Shock mitigation device.