JPH0127295B2 - - Google Patents

Description

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

(b) Prior art As a conventional hydraulic control device for an automatic transmission that regulates the oil pump discharge pressure, for example,
There is one shown in No. 144338 "Shifting device for automatic transmission" (filed on February 26, 1981). The hydraulic control device for the automatic transmission includes a pressure modifier valve that regulates a predetermined hydraulic pressure based on the throttle pressure, and a regulator valve that regulates the oil pump discharge pressure according to the predetermined hydraulic pressure. have. Throttle pressure is supplied to the pressure modifier valve during normal driving in the D range, and higher engine brake pressure is supplied during engine braking driving in the range. The pressure modifier valve is
When the supplied hydraulic pressure is below a certain pressure, the supplied hydraulic pressure is output as is, and when the supplied hydraulic pressure is higher than the fixed pressure, the pressure is reduced to the constant pressure and output. That is, the general throttle modifier pressure output in the D range is equal to the throttle pressure until the throttle pressure reaches a constant pressure, and when the throttle pressure exceeds the constant pressure, it becomes a constant pressure smaller than the throttle pressure. Further, the engine brake modifier pressure output from the pressure modifier valve in the engine brake range is always the constant pressure because the engine brake pressure is higher than the constant pressure. Since the general throttle modifier pressure or engine brake modifier pressure with these characteristics is supplied to the regulator valve, the oil pump discharge pressure (line pressure) is
In a range, if the throttle pressure is lower than a constant pressure, it will increase according to the throttle pressure,
When the throttle pressure is above a certain pressure, the pressure is regulated to a certain value (general line pressure), and in the engine brake range, the line pressure is adjusted to the above fixed value (i.e., when the throttle pressure is above a certain pressure) The pressure is regulated to the same value as the engine brake line pressure (engine brake line pressure). Such general throttle modifier pressure, engine brake modifier pressure, general line pressure and
The characteristics of engine brake line pressure are illustrated in FIG. 1.

The reason why the engine brake line pressure is kept constant regardless of the throttle pressure as described above is to ensure the required braking capacity of the band brake. In other words, in the band brake,
Brake capacity differs depending on the direction of force applied to the brake drum. When the force of the brake drum acts on the trailing side, the force from the brake drum acts in the direction of increasing the engagement force of the band brake, increasing the brake capacity, and conversely, the direction of the force of the brake drum acts in the direction of increasing the engagement force of the band brake. In the case of the leading side, this force acts in a direction that reduces the band brake engagement force, so the brake capacity decreases. Usually, a band brake is arranged so that the brake capacity is increased when driving force is applied from the engine side. Therefore, in an engine braking state in which the drive wheel is driven from the drive wheel side, the direction of force applied to the brake drum is reversed, and the braking capacity of the band brake is reduced. In this engine braking state, if the hydraulic pressure supplied to the hydraulic piston that applies the tightening force to the band brake is a hydraulic pressure that changes according to the throttle pressure, the throttle pressure is very small in the engine braking state, so the hydraulic piston The applied hydraulic pressure becomes very small and the required capacity of the band brake cannot be secured. Therefore, as shown in FIG. 1, the engine brake line pressure is kept at a constant high value even in a region where the throttle pressure is low.

However, in such conventional automatic transmission hydraulic control devices, the value of engine brake line pressure is
It always matched the highest line pressure in the D range. Therefore, the braking capacity of the band brake during engine braking is
This is equal to the brake capacity at the maximum line pressure in the D range, and there is a problem in that the brake capacity of the band brake during engine braking cannot be adjusted independently. For this reason, it has not been possible to finely adjust the shift feeling such as the shock during engine braking due to engagement of the band brake and the time until the engine brake is applied.

(C) Object of the Invention The object of the present invention is to provide a hydraulic control system for an automatic transmission that allows the brake capacity of the band brake in the engine brake range to be adjusted independently of the brake capacity in the D range.

(d) Structure of the Invention The present invention achieves the above object by making it possible to set the line pressure in the engine brake range independently of the line pressure in the D range.
That is, the present invention supplies the hydraulic pressure source port 42d of the pressure modifier valve 7 with either the throttle pressure that changes in accordance with the engine output or the engine brake pressure output in the engine brake range, whichever is higher. Shuttle valve 5
0, a pressure modifier valve that uses the hydraulic pressure supplied from the shuttle valve to the hydraulic source port as a hydraulic source and outputs a predetermined hydraulic pressure to the output port 42c, and a pressure modifier valve that outputs a predetermined hydraulic pressure to the output port 42c. The pressure modifier valve is intended for a hydraulic control device for an automatic transmission having a regulator valve 1 that regulates the oil pump discharge pressure using the predetermined hydraulic pressure as a control signal hydraulic pressure. 44 and a spring 46 that pushes the spool in one direction, and the spool has a feedback pressure receiving part (area difference between land 44b and land 44c) that generates a force opposing the spring when hydraulic pressure is applied to the spool. ), and the oil passage is configured so that the same hydraulic pressure as that of the output port acts on the feedback pressure receiving part, and the spool or a separate plug acts against the spring when hydraulic pressure acts on it. The engine brake pressure receiving part (land 44c) that generates the force
The oil passage is configured so that the engine brake pressure acts on the engine brake pressure receiving section, and the force due to the hydraulic pressure acting on the feedback pressure receiving section and the engine brake pressure receiving section is provided. If the force is smaller than the spring force, the spool is in a position that communicates the hydraulic source port and the output port, and the force due to the hydraulic pressure acting on the feedback pressure receiving part and the engine brake pressure receiving part becomes the same value as the spring force. In this case, the spool is configured to increase the amount of drain from the output port to prevent the hydraulic pressure in the feedback pressure receiving section from increasing any further. Note that the reference numerals in parentheses indicate corresponding members in the embodiments described later.

With the above configuration, when a throttle pressure lower than the first reference value (pressure determined by the force of the spring and the area of the feedback pressure receiving part) is supplied from the shuttle valve, The throttle pressure is directly outputted to the output port, while if the throttle pressure equal to or higher than the first reference value is supplied, the hydraulic pressure reduced to the first reference value is outputted to the output port. Further, when engine brake pressure is output, the engine brake pressure is supplied to the hydraulic pressure source port via the shuttle valve, and simultaneously acts on the engine brake pressure receiving section. Therefore, the pressure at the output port is reduced to a second reference value determined by the force of the spring minus the force due to the hydraulic pressure acting on the engine brake pressure receiving section and the pressure receiving area of the feedback pressure receiving section. The hydraulic pressure is output. Therefore, the engine brake line pressure in the engine brake range and the maximum value of the general line pressure in ranges other than engine brake can be set independently.

(E) Embodiments Examples of the present invention will be described below with reference to FIGS. 2 to 5 of the accompanying drawings.

First Embodiment FIG. 2 shows a schematic diagram of a 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 the rotational force from the engine output shaft E is transmitted via the torque converter T/C, an output shaft O to transmit the driving force to the final drive device, 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 of the planetary gear sets G ₁ and G ₂ (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 obtain three forward speeds and one reverse speed. be able to.

FIG. 3 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 shift valves 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 the R/B, servo apply chamber S/A, and servo release chamber S/R as specified, but other than the regulator valve 1, pressure modifier valve 7, etc. that are directly related to the present invention, Explanation of the items 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.

The regulator valve 1 has a spool 24 inserted into a valve hole 22 and a spring 26 arranged below the spool 24 in the figure. The valve hole 22 has ports 22a to 22g.
Ports 22a and 22d are drain ports. Ports 22b and 22e are oil pump O/
It is connected to a line pressure oil passage 30 to which discharge oil is supplied from P. The port 22c is connected to an oil passage 28 to which line pressure is supplied in the forward travel range. The port 22f is a port from which oil is discharged from the port 22e, and the oil discharged to the port 22f is sent to the torque converter T/C via the oil passage 32.
is supplied to The port 22g is connected to ports 42c and 42e of a pressure modifier valve 7, which will be described later, via an oil passage 34. The spool 24 has lands 24a to 24e. Lands 24c, 24d, and 24e have the same diameter, and land 24b and land 24a have smaller diameters in this order. The hydraulic pressure of the port 22b acts on the pressure receiving portion formed between the land 24a and the land 24b. Further, the oil pressure of the port 22g acts on the lower end surface of the land 24e in the figure.

The pressure modifier valve 7 includes a spool 44 inserted into a valve hole 42 and a spring 46 disposed above the spool 44 in the figure. Valve hole 42 is port 42a-42
It has f. Ports 42a and 42b are drain ports. port 42c and port 42
e communicates with the port 22g of the regulator valve 1 via the oil passage 34. Throttle pressure or engine brake pressure is supplied from the shuttle valve 50 to the port 42d as will be described later. Port 42f is oil passage 5 to which engine brake pressure is supplied.
It communicates with 8. The spool 44 has lands 44a and 44b with the same diameter, and a land 4 with a smaller diameter than these.
4c. The axial dimension of the groove between lands 44a and 44b is the same as that between port 42b and port 42.
The distance between the two walls is approximately equal to the distance between the two walls.

Port 4 of pressure modifier valve 7
2d and the oil passage 62, the throttle valve 8 is connected to the oil passage 64.
Throttle pressure is supplied through the range, and engine brake pressure is supplied from the functional valve 2 through the oil passage 58 to the range and the range. The shuttle valve 50 is capable of supplying the higher of the throttle pressure and the engine brake pressure to the oil passage 62.

Next, the operation of this embodiment will be explained. In a range other than the engine brake range (i.e. range and range), for example the D range, no oil pressure is supplied to the oil passage 58, so the shuttle valve 50 applies the throttle pressure from the oil passage 64 via the oil passage 62. It is supplied to the port 42d of the shield modifier valve 7. When this throttle pressure is low, the spool 44 is in the state shown in the right half of FIG. 1, and the throttle pressure in the oil passage 62 is supplied to the oil passage 34 as is. When the throttle pressure becomes higher than a certain pressure, the spool 44 is pushed up by the hydraulic pressure acting on the port 42e to the position shown in the left half of FIG.
b is in a slightly open state, and the pressure modifier valve 7 is in a pressure regulating state. The hydraulic pressure regulated in this way becomes a constant value (first reference value) depending on the force of the spring 46 and the pressure receiving area between the lands 44b and 44c, and this constant pressure is
4. That is, the oil pressure in the oil passage 34 (hereinafter, the oil pressure in the D range will be referred to as "general throttle modifier pressure") changes as shown by the solid line in FIG. 4 in accordance with the throttle pressure. This general throttle modifier pressure acts on port 22g of regulator valve 1. The regulator valve 1 discharges oil from the port 22e to the ports 22f and 22d to perform pressure regulation so that the oil pressure at the port 22b changes according to the general throttle modifier pressure. Due to the above-described pressure regulating action of the regulator valve 1, the oil pump discharge pressure (line pressure) becomes the general line pressure as shown in FIG. Based on the characteristics of this general line pressure, the capacity of the band brake (and other clutches, brakes, etc.) when driving from the engine side is determined.

Next, in the range or engine brake range in which the manual valve 2 is selected, engine brake pressure (hydraulic pressure having the same pressure as the line pressure) is supplied to the oil passage 58. Since this engine brake pressure is generally always higher than the throttle pressure in the oil passage 64, the engine brake pressure is supplied to the port 42d of the pressure modifier valve 7 via the shuttle valve 50. At the same time, the oil pressure in the oil passage 58 also acts on the port 42f of the pressure modifier valve 7. In this state, the pressure modifier valve 7 is in a pressure regulating state and outputs a predetermined hydraulic pressure to the oil passage 34 (hereinafter, this hydraulic pressure is referred to as "engine brake modifier pressure"). The differential pressure is a constant value determined according to the force of the spring 46 and the pressure receiving area (the area difference between the lands 44b and 44c, and the lower end surface of the land 44c in the figure) acting on the engine brake pressure spool 44. second reference value). As shown in FIG. 4, this constant value (second reference value) of the engine brake modifier pressure is the maximum value (the first
standard value). This is because land 44c of pressure modifier valve 7
This is because the area on which the engine brake pressure acts increases by the pressure receiving area. Since the regulator valve 1 performs a pressure regulating action using the engine brake modifier pressure having such characteristics,
The line pressure becomes a constant engine brake line pressure as shown in FIG. This engine brake line pressure has a value lower than the maximum value of the general line pressure. This engine brake line pressure is
The brake capacity of the band brake B during engine braking is set to be optimal. The value of this engine brake line pressure can be easily adjusted by changing the shape (pressure receiving area) of the spool 44 of the pressure modifier valve 7. Therefore, it is possible to set the brake capacity of the band brake B during engine braking independently of the brake capacity during normal driving, and the shift feeling such as the shock during engine braking and the time until the engine brake is applied can be adjusted. It can be set to be optimal.
Moreover, for this purpose, the shape of the pressure modifier valve 7 is only slightly changed compared to the conventional one, and there is no increase in price, space required, weight, etc.

Second Embodiment FIG. 5 shows a second embodiment of the present invention. however,
Only the pressure modifier valve 7' is shown. The rest of the structure is the same as that of the first embodiment shown in FIG. In this embodiment, the pressure modifier valve 7' is constituted by a spool 44' and a plug 45 having a larger diameter than the spool 44'. Also in this embodiment, when the throttle pressure is supplied from the oil passage 64, the general throttle modifier pressure is supplied to the oil passage 34, and when the engine brake pressure is supplied to the oil passage 58, the engine brake pressure is supplied to the oil passage 34. Brake modifier pressure is supplied. Engine brake modifier pressure is plug 45
and the diameter of the spool 44'. Therefore, in this embodiment, the plug 4
By changing only the diameter of the engine brake modifier pressure, the characteristics of the engine brake modifier pressure can be adjusted. Moreover, in that case, there is no need to change the diameter of the spool 44', so the general throttle modifier pressure is not affected at all. Therefore, setting the engine brake modifier pressure becomes very easy.

(F) Effects of the Invention As explained above, the hydraulic control device for an automatic transmission according to the present invention has an engine brake pressure receiving pressure where the engine brake pressure output in the engine brake range acts on the pressure modifier valve. Since the section is provided, the engine brake line pressure in the engine brake range and the maximum value of the general line pressure in the range other than engine brake can be set independently, and the degree of freedom in adjusting the brake capacity of the band brake during engine braking is increased. It is possible to provide an automatic transmission with a preferable driving feeling during engine braking.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the hydraulic characteristics of a conventional hydraulic control device for an automatic transmission, Fig. 2 is a schematic diagram of a power transmission section of an automatic transmission, and Fig. 3 is a diagram showing a hydraulic control device for an automatic transmission according to the present invention. FIG. 4 is a diagram showing hydraulic characteristics obtained by the hydraulic control device for the automatic transmission shown in FIG. 3, and FIG. 5 is a diagram showing a second embodiment of the present invention. 1...regulator valve, 7...pressure modifier valve, 50...shuttle valve.

Claims (1)

[Scope of Claims] 1. A shaft that supplies the higher of either the throttle pressure that changes in accordance with the engine output or the engine brake pressure output in the engine brake range to the hydraulic pressure source port of the pressure modifier valve. a pressure modifier valve that outputs a predetermined hydraulic pressure to an output port using the hydraulic pressure supplied from the shuttle valve to the hydraulic source port as a hydraulic pressure source; In the hydraulic control device for an automatic transmission, the pressure modifier valve includes a spool and a regulator valve that regulates the oil pump discharge pressure using the predetermined oil pressure as a control signal oil pressure. The spool is provided with a feedback pressure receiving part that generates a force opposing the spring when hydraulic pressure is applied, and the same hydraulic pressure as the output port acts on the feedback pressure receiving part. The spool or a separate plug is provided with an engine brake pressure receiving part that generates a force that opposes the spring when hydraulic pressure is applied to the engine brake pressure receiving part. The oil passage is configured so that the above engine brake pressure acts, and when the force of the hydraulic pressure acting on the feedback pressure receiving part and the engine brake pressure receiving part is smaller than the force of the spring, the spool is connected to the oil pressure source port and output. When the pressure from the hydraulic pressure acting on the feedback pressure receiving part and the engine brake pressure receiving part reaches the same value as the spring force, the spool increases the amount of drain from the output port. A hydraulic control device for an automatic transmission, characterized in that the hydraulic pressure control device for an automatic transmission is configured to prevent the hydraulic pressure in the feedback pressure receiving section from increasing any further.