JPS6241452A - Speed shift timing valve in automatic speed change gear - Google Patents

Abstract

PURPOSE:To enhance the accuracy of control, by forming a taper section in a spool in a speed shift timing valve so that the opening degree of the valve is continuously changed when the valve is opened and closed. CONSTITUTION:A taper section 10 is formed between lands of a spool 1a in a speed shift timing valve 1, and has a shape such that it is tapered toward an annular groove 1e to be connected with a circuit 5 from an annular groove 1d to be connected with a circuit 3. Accordingly, it is possible to continuously change the opening degree of the valve over the transient zone during opening or closing the valve, thereby it is possible to enhance the control accuracy of the speed shift timing valve.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a shift timing valve for an automatic transmission.

(Prior Art) Automatic transmissions are generally configured to change speed by switching the power transmission path by switching the supply and discharge of hydraulic pressure to various friction elements. By the way, in some types of gear shifting (usually downshifting from 8th gear to 2nd gear), hydraulic pressure is removed from the friction elements that control the gear shifting, and the speed is appropriately controlled for each vehicle speed. If the oil pressure is not released (shift) when the engine speed matches the engine speed after the shift (determined by the vehicle speed and the gear ratio after the shift), a large shift shock will occur.

Therefore, usually, for example, 1'-RNa issued by Nichiwa Jidosha Co., Ltd.
As described in FOIA type automatic transaxle maintenance manual J (A261003), by opening and closing the spool type shift timing valve (3-2 timing valve),
The hydraulic pressure has been removed by controlling the speed.

As shown at 1 in FIG. 6, this shift timing valve operates by moving the spool 1a against the spring 1b to apply the governor pressure PG (
(increases as the vehicle speed increases).

And valve 1 has governor pressure P.

is in the open state shown in the right half of the diagram at low vehicle speeds, and
When the governor pressure PG is high and the vehicle speed is high, valve 1 is in the closed state shown in the left half of the diagram, and circuits 3 and 5 are cut off, and circuit 8 is connected to valve l and orifice 4 by circuit 6 and orifice 7, which are parallel to each other. only to the circuit 5. Note that a check valve 8 is provided in parallel with the orifice 7, and is arranged in a direction to block oil flow from the circuit 8 to the circuit 5.

Reference numeral 9 designates a speed change valve, which has a spool 9b elastically supported by a spring 9a in a downshift position shown in the left half, and this spool is switched to an upshift position shown in the right half when a speed change pressure Ps is generated. While the shift valve 9 is in the upshift position due to the generation of the shift pressure P6, the line pressure PL is supplied to the circuit 5,
This line pressure reaches the shift friction element 2 via the check valve 8 and the circuit 8, allowing the third speed to be selected.

When the speed change pressure PS disappears and the speed change valve 9 is in the downshift position, the circuit 5 is connected to the Drainbow 90, and the oil pressure of the speed change friction element 2 is removed while the speed is controlled as follows. That is, at low vehicle speeds where the governor pressure PG is low, the shift timing valve 1 is in the right half position in the figure, and the hydraulic pressure of the element 2 is applied not only to the orifice 7 (opening degree B) but also to the orifice 4 (
It is removed even after opening degree a), and the removal speed is fast. On the other hand, when the governor pressure PG is high and the vehicle speed is high, the shift timing valve 1 is in the left half position in the figure, and the hydraulic pressure of the element 2 is removed only through the orifice 7, and the removal speed is slow.

(Problem to be Solved by the Invention) However, the shift timing valve 1 has a configuration in which the oil pressure is removed from the element 2 by switching the throttle opening in two stages: a+B (at low vehicle speed) and Bc (at high vehicle speed). As a result, the following situation occurred. That is, assuming that the governor pressure PG changes with respect to the vehicle speed as shown by X in Fig. 3, the above-mentioned throttle opening is determined at low vehicle speeds below 70, which corresponds to PG=PG0, as shown by y in the figure. At a high vehicle speed of 70 or higher, the formula becomes a+B.

However, for the opening degree of the throttle, although the preferred value at vehicle speeds below 72 corresponding to PG = PG2 and the preferred value at vehicle speeds of 78 or higher corresponding to PG8 are fixed, the preferred value at vehicle speeds between 72 and 78 is fixed. Not constant, ■,
It gradually decreases as the vehicle speed increases from V3 to V3. Therefore, when the vehicle speed is less than 72, the release/throttle opening degree a+B can be a suitable value, and the oil pressure of the friction element 2 can be removed at the targeted speed as shown by α in FIG. When the engine speed after the shift (determined by the vehicle speed and the gear ratio after the shift) is exactly reached as shown in the middle β, the above omission (3→
2 downshift) can be completed to prevent the occurrence of shift shock. In addition, even when the vehicle speed is 73 or higher, the throttle opening degree B can be a suitable value, and the hydraulic pressure of the friction element 2 can be removed at the desired reverse speed as indicated by αl in Fig. 5, and the engine speed is the same. As shown by βI in the figure, the above-mentioned handling can be completed when the engine speed has just reached the post-shift engine speed, thereby preventing the occurrence of shift shock.

However, at vehicle speeds between 70 and 72, the aperture opening a and B are too large, and the hydraulic pressure of the friction element 2 is released at the same speed as shown by α in FIG. If the engine speed is too high, the speed change ends before the engine speed reaches the post-shift engine speed, resulting in a sudden change in the engine speed as shown by γ in FIG. 5, which inevitably increases the speed change shock. Also, when the vehicle speed is between 70 and 78, the throttle opening B is too small and the oil pressure of the friction element 2 is αI in Fig. 5.
As shown in , the engine will come out at the same speed, and the engine will come out at a speed that is too slow than the preferred speed, and the engine will start racing as shown by δ in Figure 5. When the engine speed settles to the speed after the shift, at the end of the shift. , racing due to the difference in engine speed inevitably causes a shock.

(Means for Solving the Problems) In order to solve these problems, the present invention makes it possible to continuously change the throttle opening in the opening/closing transition region of the shift timing valve, thereby reducing the hydraulic pressure. In an automatic transmission comprising a friction element that is supplied and discharged to control gear shifting, and the speed of removing hydraulic pressure from the friction element is controlled by opening and closing a spool-type shift timing valve, the spool of the shift timing valve is equipped with: The present invention is characterized in that a tapered portion is provided so that the opening and closing of the vent valve is performed while continuously changing the degree of opening.

C) The friction element can be supplied with and discharged from hydraulic pressure to change gears. When shifting by supplying and discharging hydraulic pressure from friction elements,
The supply and discharge speed of the hydraulic pressure is controlled by opening and closing the shift timing valve, and when the engine speed exactly matches the engine speed after the shift, the supply and discharge of the hydraulic pressure, that is, the corresponding shift can be completed, and the shift is completed. By the way, the tapered part provided on the spool of the shift timing valve allows the opening and closing of the shift timing valve to be continuously changed.
Therefore, the supply and discharge speed of the hydraulic pressure can be continuously changed in the opening/closing transition region of the shift timing valve. Therefore, even in the transient region, the oil pressure can be removed to a suitable speed, and when the engine speed matches the rotation speed after the gear shift, the oil pressure can be supplied and discharged, that is, the corresponding gear shift can be completed. This can prevent the occurrence of shock.

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

FIG. 1 shows an embodiment of the present invention, in which the same parts as in FIG. 6 are designated by the same reference numerals. In this example, the circuit 3 to the orifice shown by 4 in FIG. 6 is removed, and in its place a tapered portion 10 is provided between the lands of the spool 1a. The tapered portion 10 extends from the annular groove 1d of the shift timing valve 1 to which the circuit 3 is to be connected to the shift timing valve 1 to which the circuit 5 is to be connected.
The annular strip 1711e has a tapered shape. In this way, the tapered part 10 forms a variable orifice whose opening degree changes as shown by A in FIG. 2 between the opening corner part 1f of the groove 1d near the groove 1e, and this variable orifice When the spool 1a is at the limit position shown in the left half of FIG. 1, the opening degree A is set to the maximum Amax, and as the spool 1a strokes toward the limit position shown in the left half of FIG. , finally made O.

Note that the spool 1a has a governor pressure P corresponding to the vehicle speed v2 in FIG. 3 or more, it rises in the figure from the half position in Figure 1,
Governor pressure P corresponding to vehicle speed v8. The spring force and spring constant of the spring 1b are determined so that the groove 1d is closed (variable orifice opening A=0) at 8 or more. As a result, when using the shift timing valve 1 in this example, the opening degree of the throttle opening is the 8th.
It is shown as 2 in the figure.

As shown, it is fixed at Amax + B (B is the opening of the fixed orifice 7) when the vehicle speed is less than 72, and at B when the vehicle speed is 78 or more. Changes to

The operation of the above embodiment will be explained next.

The shift valve 9 is in the upshift position shown on the right half, and the shift friction element 2 is supplied with hydraulic pressure (line pressure) to perform a shift (upshift) in the same manner as described above with reference to FIG. Ru.

When the speed change valve 9 is switched to the downshift position shown in the left half, the oil pressure of the friction element 2 is removed from the circuit 5 and Dorenboe 9C as described below, and a downshift is performed.

That is, vehicle speed V in FIG.

When the vehicle speed is less than (P, = Po,), the shift timing valve 1 is at the half position in Fig. 1, and the variable orifice opening degree is A.
is set to the maximum value Amax, and the oil pressure of the friction element 2 is set at a high speed determined by the total opening of this opening Amax and the opening B of the fixed orifice, that is, the speed shown by α in Fig. 4 (α in Fig. 5).・When the engine speed reaches the speed after the shift, as indicated by β in the figure (same as β in Figure 5), the above-mentioned hydraulic pressure removal (downshift) is completed. This prevents shift shock from occurring.

In Fig. 3, when the vehicle speed is higher than v8 (PG = PG8), the shift timing valve 1 is located in the left half position in Fig. 1, and the variable orifice opening A is set to 0, and the hydraulic pressure of the friction element 2 is fixed orifice. 7, and at a low speed determined by the opening degree B, that is, at a speed shown in the left half of Fig. 1 (same as αI in Fig. 5), and the engine rotation speed is
(Same as βI in FIG. 5), when the rotational speed after the shift is reached, the above-mentioned oil pressure removal (downshift) is terminated, thereby preventing the occurrence of a shift shock.

By the way, between the vehicle speeds V and V3, the speed change timing valve 1 continuously changes the variable orifice opening A between Amax and 0, and the throttle opening A+B is set as shown by 2 in FIG. 3. Therefore, the oil pressure of the friction element 2 is at this opening A+B
In the case of medium vehicle speed, α' in Fig. 4 is determined by
The engine rotation speed is β in the figure.
By ending the above-mentioned hydraulic pressure removal (downshifting) when the rotational speed reaches exactly after the gearshift as shown in ', it is possible to prevent the occurrence of gearshift shock. In order to obtain this effect, the optimum value for the throttle opening is as the vehicle speed increases from V2 to V8.
As the speed gradually decreases, the speed change timing valve 1 of the present invention changes the throttle opening degree to the corresponding vehicle speed range v2 to v, as shown by 2 in Fig. 3.
Since the change is made to match the above-mentioned preferred value in step 3, the above-mentioned shift shock prevention effect can be reliably achieved at any vehicle speed.

Furthermore, it is clear that the present invention can also be applied to a device that changes speed by supplying hydraulic pressure to a certain friction element and adjusts the supply speed thereof.

(Effects of the Invention) As described above, the speed change timing valve of the present invention is configured such that the spool is provided with a tapered portion 1o so that the speed change timing valve is opened and closed while continuously changing the adjustment.
It is possible to continuously change the supply/discharge throttle opening A+B in the above-mentioned transition region of opening/closing, and therefore, the supply/discharge throttle opening can be controlled to a suitable value under any conditions, and the engine speed is adjusted to just after the gear shift. When the rotational speed reaches , the hydraulic supply and discharge of the friction element 2 is terminated, and the effect of preventing the occurrence of shock can be always reliably achieved.

[Brief explanation of drawings]

Fig. 1 is a hydraulic circuit diagram of the main parts of an automatic transmission showing an embodiment of the shift timing valve of the present invention, Fig. 2 is an enlarged view of the main parts of the same shift timing valve, and Fig. 3 is a diagram of the same shift timing valve. Figure 4 is a diagram showing the throttling characteristics in comparison with that of a conventional shift timing valve. Figure 4 is a shift operation time chart when the shift timing valve of the present invention is used. Figure 5 is a diagram showing the speed change operation time chart when the shift timing valve of the present invention is used. Fig. 6 is a hydraulic circuit diagram of a main part of an automatic transmission showing a conventional shift timing valve. 1...Shift timing valve 1a...Spool 1b.
...Spring 1c...Chamber 1d, 1e...
Annular groove 1f... Opening corner 2... Friction element 7... Fixed orifice A... Variable orifice opening degree B... Fixed orifice opening degree 8... Check pulp 9... Speed change Valve 10... Taper portion Patent applicant Nissan Motor Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Scope of Claims] 1. An automatic transmission comprising a friction element to which hydraulic pressure is supplied and discharged to control gear shifting, and the speed at which the hydraulic pressure is supplied and discharged is controlled by opening and closing a spool-type shift timing valve, comprising: 1. A shift timing valve for an automatic transmission, characterized in that a spool of the timing valve is provided with a tapered portion so that the valve is opened and closed while continuously changing its opening degree.