JPH0348381B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a hydraulic control device for a transmission.

(B) Prior Art A conventional hydraulic control device for a transmission is disclosed in, for example, Japanese Patent Laid-Open No. 77155/1983.
In this hydraulic control device for a transmission, line pressure is regulated according to throttle pressure (and gear ratio), and throttle pressure is controlled based on engine intake pipe negative pressure. That is, the throttle pressure is set to decrease as the engine intake pipe negative pressure increases. However, the line pressure is not allowed to fall below a predetermined minimum value. That is, once the line pressure decreases to a predetermined minimum value, it is thereafter maintained at the minimum value even if the engine intake pipe negative pressure increases. An example of such hydraulic characteristics is shown in Part 9.
As shown in the figure.

(c) Problems to be Solved by the Invention The line pressure characteristics obtained by the conventional transmission hydraulic control device are set as shown in FIG. 9 for the following reason. That is, the engine torque changes as shown by the solid line in FIG. 9 according to the negative pressure in the engine intake pipe. The maximum torque is reached when the negative pressure is 0 (or a predetermined positive pressure value when using a turbocharger), the torque becomes 0 when the predetermined negative pressure is 400 mmHg, and the negative pressure increases further in the engine braking state (reverse drive state). do. Even under engine braking conditions, the capacity of clutches, pulleys, etc. of transmissions such as automatic transmissions and continuously variable transmissions is required to accommodate the reverse driving force, so as shown by the broken line in Figure 9, engine torque is It is necessary to secure a capacity that can transmit a value in which the negative part is folded back to the positive side. Therefore, the line pressure characteristics are set high so that the torque indicated by the broken line can be transmitted even in a region where the negative pressure in the engine intake pipe is large. Therefore,
When the negative pressure is around 400mmHg, the throttle pressure and the line pressure that is regulated accordingly are higher than necessary. This area is used during steady driving and is the area that is used the longest, but if the line pressure is higher than necessary in this area, oil pump loss increases and transmission efficiency decreases. This is a major cause of this. This has a particularly large effect in the case of a V-belt continuously variable transmission in which transmission efficiency is greatly affected by line pressure. The present invention aims to solve the above problems.

(d) Means for solving the problems The present invention approximates the required torque characteristics by using two diaphragms in which the direction of force applied during negative pressure is opposite to each other and the pressure receiving area is different. The above problems are solved by obtaining hydraulic characteristics. That is, in the transmission hydraulic control device according to the present invention, the vacuum diaphragm unit
A diaphragm, a second diaphragm arranged parallel to the first diaphragm and having a larger pressure receiving area, a negative pressure chamber partitioned between the first diaphragm and the second diaphragm, and a pushing force of the first diaphragm. The distance between the rod that transmits the pressure to the pressure regulating valve, the first spring that applies a force to the first diaphragm from the negative pressure chamber side toward the atmospheric pressure acting side, and the first diaphragm and the second diaphragm is a predetermined distance. (i.e., when the second diaphragm is displaced by a predetermined amount toward the first diaphragm)
It has a transmission member capable of transmitting a pushing force between them, and a second spring that applies a force to the second diaphragm from a surface on the negative pressure chamber side to a surface on the atmospheric pressure acting side.

(E) Effect When the engine intake pipe negative pressure is relatively low, the second diaphragm is pushed by the second spring and is displaced in a direction away from the first diaphragm. Therefore, the transmission member is in a state in which it is unable to transmit the pushing force of the second diaphragm to the first diaphragm, and the second diaphragm is in a state in which it does not function at all with respect to the rod. In this state, only the pushing force of the first diaphragm is transmitted to the spool of the pressure regulating valve via the rod. 1st
As the negative pressure increases, the diaphragm receives a force that reduces the force of the first spring, so the force acting on the rod gradually decreases.
That is, the hydraulic pressure regulated by the pressure regulating valve decreases as the negative pressure increases. As the engine intake pipe negative pressure increases, the force acting on the second diaphragm gradually increases due to the difference between atmospheric pressure and negative pressure, and the second diaphragm resists the force of the second spring. Displaced in the direction of compression. When the negative pressure reaches a predetermined value, the second diaphragm becomes capable of transmitting force to the first diaphragm via the transmission member. If the negative pressure further increases, the second diaphragm will apply a pushing force to the first diaphragm, and the force from the first diaphragm and the force from the second diaphragm will act on the rod in combination. The force of the first diaphragm generated by negative pressure decreases as the negative pressure increases, while the force of the second diaphragm generated by negative pressure increases as the negative pressure increases, but the pressure receiving area of the second diaphragm Since this is made larger than the pressure receiving area of the first diaphragm, the influence of the force of the second diaphragm is greater, and as a result, a force acts on the rod that increases as the negative pressure increases. Therefore, the hydraulic pressure regulated by the pressure regulating valve increases as the negative pressure increases. As a result, the oil pressure obtained by the pressure regulating valve decreases as the negative pressure increases when the negative pressure is below a predetermined value, and increases as the negative pressure increases when the negative pressure value exceeds the predetermined value. The hydraulic characteristics are as shown in Figure 2. When hydraulic pressure (throttle pressure) having such characteristics is applied to the line pressure regulating valve, line pressure characteristics as shown in FIG. 3 can be obtained. This makes it possible to obtain line pressure characteristics that approximate the required torque characteristics. Note that if a spring is provided that constantly applies force to the spool of the pressure regulating valve, the pressure regulating value will not fall below a predetermined value corresponding to the force of this spring.
Hydraulic characteristics as shown in FIG. 5 are obtained. In addition to using this spring, by further adjusting the setting forces of the first spring and the second spring, the hydraulic characteristics as shown in FIG. 6 can be obtained.
In addition, by adjusting the ratio of the pressure receiving area of the first diaphragm and the pressure receiving area of the second diaphragm,
The degree of change in the pressure regulation value with respect to the change in negative pressure can be set arbitrarily.

(F) Example (First Example) FIG. 1 shows a first example of the present invention. The hydraulic control device for this transmission includes a vacuum diaphragm unit 10 and a throttle pressure 12 which is a pressure regulating valve. Vacuum diaphragm unit 1
0 has two diaphragms arranged parallel to each other in a casing 14, namely a first diaphragm 16 and a second diaphragm 18. The second diaphragm 18 is fixed by being sandwiched between a fixing member 20 and a fixing member 22 provided in the casing 14, and the first diaphragm 16 is sandwiched between the casing 14 and the fixing member 20. It is fixed by this.
A negative pressure chamber 24 is defined by the first diaphragm 16, the second diaphragm 18, and the fixing member 20. Note that the second diaphragm 18 has a pressure receiving area approximately twice that of the first diaphragm 16. An atmospheric pressure chamber 26 is provided on the surface of the first diaphragm 16 opposite to the negative pressure chamber 24, and an atmospheric pressure chamber 28 is provided on the surface of the second diaphragm 18 opposite to the negative pressure chamber 24. It is provided. The negative pressure chamber 24 is connected to the negative pressure inlet 2 by a passage 20a provided in the fixed member 20 and a passage 22a provided in the fixed member 22.
2b. The negative pressure inlet 22b is connected to the intake pipe of the engine. Note that a seal member 30 is provided between the fixing member 22 and the casing 14 to prevent leakage of negative pressure. A first spring 32 is provided between the first diaphragm 16 and the second diaphragm 18 to apply a force in a direction that moves them away from each other. Further, a second spring 34 is provided between the second diaphragm 18 and the fixing member 20, which applies a force in a direction to move the second diaphragm 18 away from the first diaphragm 16. A transmission member 36 is provided integrally with the first diaphragm 16. The transmission member 36 does not contact the second diaphragm 18 when the second diaphragm 18 is displaced by the second spring 34 as shown in the upper half of FIG. The second diaphragm 18 is in contact with the second diaphragm 18 when the second diaphragm 18 is in the central position as shown in FIG. In addition, the first diaphragm 16
A metal fitting 38 is fixed to the atmospheric pressure chamber 26 side, and a rod 40 is connected to this metal fitting 38 by a screw. The casing 14 is provided with an integral mounting fitting 42, and the vacuum diaphragm unit 10 is attached to the valve body 44 at a position where the throttle valve 12 is provided by screws provided on the outer periphery of the mounting fitting 42.
The throttle valve 12 is comprised of a spool 48 fitted into a valve hole 46. The valve hole 46 is provided with five ports 46a to 46e.
The ports 46a and 46c communicate with an oil passage 50 which is a throttle pressure circuit, the port 46b communicates with a line pressure oil passage 52, and the ports 46d and 46e are drain ports. The spool 48 is in the pressure regulating position shown in FIG. 1, and by draining a portion of the oil supplied from the port 46b to the port 46d, the oil pressure of the port 46a, that is, the oil pressure of the oil passage 50, acts on the spool 48 from the rod 40. Adjust the pressure to balance the force.

Next, the operation of this embodiment will be explained. The negative pressure inlet 22b is connected to the engine intake pipe,
Engine intake pipe negative pressure acts on the negative pressure chamber 24 via the passage 22a and the passage 20a. When the negative pressure in the engine intake pipe is relatively low (close to atmospheric pressure), the pressure difference between the negative pressure chamber 24 and the atmospheric pressure chamber 28 is small, so it acts on the second diaphragm 18 to the left in FIG. The force based on this pressure difference is small, and the second diaphragm 18 is pushed to the right by the second spring 34 and is in a displaced state (first
state shown in the upper half of the figure). Therefore, the transmission member 3
6 is not in contact with the second diaphragm 18, and the second diaphragm 18 and the first diaphragm 16 are in a mutually unrelated state. Therefore, only the force exerted by the first diaphragm 16 acts on the rod 40. On the other hand, since the pressure difference between the negative pressure chamber 24 and the atmospheric pressure chamber 26 is small, the force acting on the first diaphragm 16 in the right direction in FIG. The small first diaphragm 16 exerts a force on the rod 40 in a direction to the left in FIG. The pushing force acting on the rod 40 decreases as the negative pressure in the negative pressure chamber 24 increases. In other words, the pushing force against the rod 40 is inversely proportional to the negative pressure. Since the throttle valve 12 regulates the oil pressure in the oil passage 50, that is, the throttle pressure, in accordance with the force acting on the spool 48 from the rod 40, the throttle pressure is
It gradually decreases as the negative pressure increases, as indicated by the symbol a in the figure. When the negative pressure reaches a predetermined value (400 mm/Hg in the example shown in FIG. 2), the force generated on the first diaphragm 16 due to the negative pressure in the negative pressure chamber 24 and the force exerted by the first spring 32 become equal, and the force from the rod 40 is The force acting on the spool 48 becomes zero, and the throttle pressure also becomes zero. On the other hand, when the negative pressure reaches this predetermined value, the force acting on the second diaphragm 18 increases due to the negative pressure in the negative pressure chamber 24, and the second diaphragm 18 increases.
The diaphragm 18 moves to the left in FIG. 1 and comes into contact with the transmission member 36 (the state shown in the lower half of FIG. 1). That is, the second diaphragm 1
8 connects to the first diaphragm 16 via the transmission member 36
begins to exert a pushing force on the Second diaphragm 18
from the first diaphragm 16 via the transmission member 36
The force transmitted to the pump increases as the negative pressure increases. On the other hand, the force directed to the right in FIG. 1 against the first diaphragm 16 due to the negative pressure in the negative pressure chamber 24 decreases as the negative pressure increases. However, since the pressure receiving area of the second diaphragm 18 is larger than the pressure receiving area of the first diaphragm 16, the pushing force of the second diaphragm 18 increases at a larger rate than the force of the first diaphragm 16 in the opposite direction. . Therefore, a force acts on the rod 40 that increases as the negative pressure in the engine intake pipe increases. As a result, the throttle pressure in the oil passage 50, which is regulated by the throttle valve 12, also increases in accordance with the increase in engine intake pipe negative pressure. That is, it becomes as shown by the symbol b in FIG. As a result, the throttle pressure in the oil passage 50 obtained by the vacuum diaphragm unit 10 and the throttle valve 12 has characteristics as shown in FIG. If the throttle pressure in the oil passage 50 is applied to a line pressure regulating valve (not shown) and the line pressure is regulated according to the throttle pressure, it is possible to obtain a line pressure having characteristics as shown in FIG. 3, for example. . The line pressure characteristics shown in FIG. 3 correspond to the theoretically required torque capacity. This ensures proper line pressure across the entire range of engine intake pipe negative pressure, eliminates unnecessarily high pressure areas, reduces oil pump losses, and improves transmission efficiency in the case of V-belt continuously variable transmissions. will improve.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention. This second
The embodiment is different from the first embodiment shown in FIG.
Spring 60 that constantly applies force to spool 48
is added. The other configurations are the same as in the first embodiment. As a result, the pressure adjustment value increases by the force of the spring 60, so that hydraulic characteristics as shown in FIG. 5 can be obtained. In addition to this, if the negative pressure value at which the pushing force of the first diaphragm 16 becomes 0 is set to a value smaller than the negative pressure value at which the second diaphragm 18 contacts the transmission member 36 (this means that the first spring 32 and (which can be easily adjusted by changing one or both of the second springs 34), the hydraulic characteristics can be as shown in FIG. That is, rod 40
the first diaphragm 16 and the second diaphragm 1
A region is formed in which no force is applied from any of the springs 8, and a constant throttle pressure corresponding to the force of the spring 60 is obtained in this region (the portion indicated by the symbol c in FIG. 6). This makes it possible to obtain throttle pressure characteristics as shown in FIG. 6, and also to obtain line pressure characteristics corresponding to these characteristics. The line pressure characteristics in this case also approximate the required torque characteristics shown in FIG. Therefore, the same effects as in the first embodiment can be obtained. Incidentally, the inclination of the portions a and b in FIGS. 5 and 6 can be arbitrarily set by adjusting the pressure receiving areas of the first diaphragm 16 and the second diaphragm 18. The boundary between a and c in Figure 6 and b
It is clear that the negative pressure value at the boundary between c and c can also be set as desired.

(Third Embodiment) FIG. 7 shows a third embodiment of the present invention. This third
In this embodiment, the throttle valve 12 of the second embodiment shown in FIG. 4 is replaced with a line pressure regulating valve 70. The construction of the vacuum diaphragm unit 10 is similar to the embodiment described above. Line pressure regulating valve 7
0 is a general line pressure regulating valve that regulates the oil pressure of the oil passage 74, that is, the line pressure, by discharging a part of the oil in the oil passage 74, to which the oil discharged from the oil pump 72 is supplied, to the drain port 76. It is.
Since the line pressure of the oil passage 74 is regulated to balance the pushing force of the rod 40, it is possible to obtain line pressure characteristics as shown in FIG. 8, for example.

(G) Effects of the Invention As explained above, according to the present invention, the pressure regulating valve is controlled by a diaphragm unit that combines two diaphragms whose pushing force change characteristics with respect to changes in negative pressure are opposite to each other. Therefore, when the negative pressure is small, the oil pressure decreases as the negative pressure increases, and when the negative pressure becomes large, the oil pressure increases as the negative pressure increases, and the line pressure characteristics are appropriate according to the required torque. It can be done. This reduces oil pump loss and improves transmission efficiency in the case of a V-belt continuously variable transmission, resulting in a highly efficient transmission.

[Brief explanation of drawings]

1 is a diagram showing the first embodiment of the present invention, FIG. 2 is a diagram showing the throttle pressure characteristics obtained by the first embodiment, FIG. 3 is a diagram showing the line pressure characteristics, and FIG. 4 is a diagram showing the line pressure characteristics.
The figure shows a second embodiment of the present invention, and FIG.
FIG. 6 is a diagram showing another throttle pressure characteristic obtained by the second embodiment. FIG. 7 is a diagram showing the throttle pressure characteristic obtained by the second embodiment.
FIG. 8 is a diagram showing the line pressure characteristics obtained by the third embodiment, and FIG. 9 is a diagram showing the torque characteristics of the engine and the conventional line pressure characteristics. 10...Diaphragm unit, 12...Throttle valve (pressure regulating valve), 16...First diaphragm,
18...Second diaphragm, 24...Negative pressure chamber, 3
2...first spring, 34...second spring, 36...transmission member, 40...rod.

Claims (1)

[Scope of Claims] 1. A transmission having a vacuum diaphragm unit that generates a pushing force that changes based on the applied negative pressure, and a pressure regulating valve that regulates hydraulic pressure according to the pushing force from the vacuum diaphragm unit. In the hydraulic control device, a vacuum diaphragm unit is partitioned between a first diaphragm, a second diaphragm arranged parallel to the first diaphragm and having a larger pressure receiving area, and the first diaphragm and the second diaphragm. a negative pressure chamber, a rod that transmits the pushing force of the first diaphragm to the pressure regulating valve, and a first spring that applies a force to the first diaphragm from a surface on the negative pressure chamber side to a surface on the atmospheric pressure acting side; A transmission member capable of transmitting a pushing force between the first diaphragm and the second diaphragm when the distance between them decreases to a predetermined value; A hydraulic control device for a transmission, characterized in that it has a second spring that applies a force of. 2. The hydraulic control device for a transmission according to claim 1, wherein the pressure regulating valve has a spring that always applies a force in the direction of increasing the pressure regulating value to its spool.