JPS6150182B2 - - Google Patents

Description

[Detailed Description of the Invention] (1) Technical Field The present invention relates to a lock-up torque converter that is inserted into a power transmission system of an automatic transmission, etc., and particularly to a slip control that controls the relative rotation (slip) between input and output elements of the lock-up torque converter. It is related to the device.

(2) Prior art A lock-up torque converter converts the output element (usually a turbine runner) under the reaction force of a stator (reaction force element) by stirring hydraulic oil from an input element (usually a pump inverter) driven by an engine. There are two operating modes: one in which the input and output elements are directly connected by coupling the lock-up clutch and the rotation toward the input element is directly transmitted to the output element (lock-up condition). The former operating mode is used in relatively low engine speed ranges where engine torque fluctuations are a problem and an increase in torque is required, and the latter operating mode is used in other high engine speed ranges. . Therefore, compared to a normal torque converter that only has the former operating mode, a lock-up torque converter can eliminate slip between input and output elements in a high engine speed range (high vehicle speed range).
Engine fuel efficiency can be improved.

By the way, if the lock-up torque converter is used to switch only between the two operating modes mentioned above, the lock-up vehicle speed, which is the criterion for switching, cannot be set to such a level that the engine torque fluctuation becomes so small that the vehicle body no longer vibrates. It is necessary to set the vehicle speed to a high speed, and the lockup period becomes short, making it impossible to achieve a sufficient improvement in fuel efficiency.

Therefore, although engine torque fluctuations may be a slight problem, the lock-up clutch is engaged while sliding in a low engine speed range where the engine output torque is sufficient, thereby absorbing engine torque fluctuations so that they do not become a problem. At the same time, the applicant of the present application previously filed a patent application filed in 1983 for a slip-controlled lock-up torque converter which limits the slip of the torque converter and eliminates the above-mentioned problems.
It was previously proposed in No. 196897.

This slip-controlled torque converter connects an output element to a lock-up clutch that performs the above-mentioned slip restriction in response to a differential pressure between a converter chamber and a lock-up control chamber, and connects the output element to a pair of opposing hole grooves as shown in FIG. A, b and a ball c interposed between these pawl grooves drive the output element and the lock-up clutch so that they can be relatively displaced according to the transmission torque difference, and the opening degree can be changed by the relative displacement. The structure includes a variable orifice that can control the slip by adjusting the degree of communication between the converter chamber and the lockup control chamber.

However, in this lock-up torque converter, the angle θ formed by the bottom surfaces of ball grooves a and b and the rotating surfaces of the output element and lock-up clutch is the same over the entire length of the ball groove, and this angle θ is set between the output element and the lock-up clutch. The transmission torque ratio of the up clutch is determined to be constant. Here, if the transmission torque of the output element becomes excessive and the transmission torque ratio described above deviates from the constant value, the output element will be displaced relative to the lock-up clutch in the forward direction of rotation as shown by the solid line arrow in Fig. 10. By reducing the opening degree of the variable orifice and reducing the pressure in the lockup control chamber, the coupling force of the lockup clutch is strengthened to return the transmission torque ratio to a constant value, and conversely, the transmission torque of the output element becomes too small and the transmission torque increases. When the ratio deviates, the output element is displaced relative to the lock-up clutch in the direction of rotation shown by the dotted arrow in FIG. It functions to weaken the force and return the transmission torque ratio to a constant value. In other words, it functions to keep the transmission torque ratio constant by constantly feeding back changes in the transmission torque ratio to increase or decrease the opening degree of the variable orifice.

However, if the bottom surface inclination angle θ of the ball grooves a and b is made the same over the entire length of the ball groove, the above-mentioned relative displacement with respect to the deviation in the transmission torque ratio becomes large, and therefore the amount of feedback becomes large, and the variable orifice The change in the opening degree, that is, the change in the pressure in the lockup control chamber (lockup release pressure) (change in the coupling force of the lockup clutch) also increases.

On the other hand, in the slip control hydraulic system, as shown in FIG. 11, when the variable orifice opening decreases by ΔS and the lock-up release pressure decreases accordingly, the response delay T ₁ (approximately 0.1 seconds) and the delay time This is a first-order delay system that maintains the release pressure at a predetermined value with T ₂ (approximately 0.3 seconds). Therefore, when the relative displacement amount with respect to the deviation in the transmission torque ratio is large as described above, excessive feedback is applied, and as shown in FIG. The rotational speed also abnormally deviates from the torque converter output shaft rotational speed, or hunts abnormally close to it. At the former point, a humming noise occurs due to the increase in engine rotational speed, and at the latter point, vibrations due to lockup occur. It is inevitable that it will occur.

(3) Object of the Invention An object of the present invention is to solve the above-mentioned problem by reducing the ratio of the relative displacement to a change in the transmission torque ratio as the difference in the transmission torque ratio increases.

(4) Structure of the Invention For this purpose, the slip control device of the present invention, in the lock-up torque converter, adjusts the bottom inclination angle of the ball groove so that the transmission torque difference increases as the relative displacement of the variable orifice progresses in the closing direction. The structure is characterized in that the ratio of the relative displacement to a change in is reduced.

(5) Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a lock-up torque converter equipped with the device of the present invention. In this figure, 1 indicates a torque converter, and the torque converter 1 includes a pump impeller (torque converter input element) 2 and a turbine runner (torque converter output element) 3. It mainly consists of a stator 4 and a stator 4. The pump impeller 2 is drive-coupled to an engine crankshaft (not shown) via a converter cover 5 welded thereto, and is constantly driven by this during engine operation. A hollow pump drive shaft 6 is further welded to the pump impeller 2, and a pump 7 is constantly driven via this shaft during engine operation.

The turbine runner 3 has rivets 8 on its inner peripheral edge.
The turbine runner 3 is slidably fitted onto a sleeve 10 via which the turbine hub 9 is riveted, and the sleeve 10 is splined to the torque converter output shaft 11 so as not to move in the axial direction. It forms part of the output shaft 11. Flanges 9a and 10a facing each other and extending radially outward are integrally formed on the turbine hub 9 and the sleeve 10, respectively, and these flanges are slidably and rotatably fitted to each other to provide a connection between the two. A pressure chamber 12 is defined in the pressure chamber 12 . Ball grooves 13 and 14 are formed on the opposing surfaces of flanges 9a and 10a, respectively, and these ball grooves 13 and 1
4 extend at at least three locations along an arc of radius R centered on the torque converter output shaft 11, and are opposed to each other.

As shown expanded in FIG. 5, the ball grooves 13 and 14 are formed so that the ball 15 is rollingly clamped between the bottom surfaces 13a and 14a, and these grooves hold the flange 9a and therefore the turbine runner 3 against the flange 10a. A cam mechanism is configured for drive coupling so as to allow relative displacement according to the transmission torque difference between the two. Ball groove 1
3 and 14 are made point symmetrical with respect to the center of the ball 15 for this purpose, and the shape of the bottom surface of the ball groove 14 is selected as described below with reference to FIG.

In FIG. 6, the deepest point of the ball groove bottom surface 14a is designated as A, and the bottom surface 14a and the flange 10
Let the intersection point with the surface of a be B, and the groove bottom surface 1 at point A
Assuming an x-coordinate system in the same direction as the tangent line of 4a, and assuming that the point on the x-coordinate system corresponding to point A is 0 and the point on the x-coordinate system corresponding to point B is x ₁ , the pole 15 is in the groove. The angle θ that the tangent of the groove bottom surface 14a makes with the rotating surface of the flange 10a at the point x where it contacts the bottom surface 14a is θ ₁ when x=A (x=0), x=B (x=
x ₁ ) so that θ ₂ is obtained. And θ
₂ > θ ₁ , and points A and B so that the inclination angle θ of the groove bottom surface 14a gradually increases from θ ₁ to θ ₂ as you go from point The shape of the groove bottom surface 14a in between is selected.

As shown in FIG. 1, a lock-up clutch 16 is separately slidably fitted onto the sleeve 10, and when the lock-up clutch 16 presses its outer peripheral clutch facing 16a against the converter cover 5, the converter A lockup control room 18 isolated from the room 17 is created. The lockup control chamber 18 is a hole 1 formed in the sleeve 10.
0b and 10c to communicate with the pressure chamber 12 at all times, and communicate with the converter chamber 17 through holes 10b and 10d in the sleeve 10 and a hole 9b formed in the turbine hub 9. In addition, as shown in Fig. 7, the hole 9b
is a rectangular hole, and the hole 10d is a slit that overlaps the hole 9b and extends in the circumferential direction, and these constitute a variable orifice 19 whose opening degree S shown by diagonal lines in FIG. 7 is changed depending on the amount of overlapping. The variable orifice adjusts the degree of communication between the converter chamber 17 and the lockup control chamber 18 according to its opening degree. The variable orifice 19 is fully opened when its opening degree S is x=0 in relation to the cam mechanism;
It is fully closed when x=x ₁ , and is configured to change linearly between these as shown in FIG. It is also possible to form an orifice in the hole 10c in order to improve stability when feeding back the hydraulic pressure in the lockup control chamber 18 to the pressure chamber 12 and to prevent hunting during step response.

An annular member 20 having an L-shaped cross section is further fixed to the lock-up clutch 16, and the lock-up clutch 16 is fixed by meshing the teeth 20a formed on the free end edge of the annular member 20 with the teeth 10e formed on the outer peripheral edge of the flange 10a. It is drivingly coupled to the sleeve 10 for relative axial movement.

The stator 4 of the torque converter 1 is placed on a hollow fixed shaft 22 via a one-way clutch 21, and annular passages 23, 2 are provided between the shaft 22 and the pump drive shaft 6 and the torque converter output shaft 11, respectively.
Set 4. The annular passage 23 guides the hydraulic oil from the oil pump 7 into the torque converter 1 and removes this hydraulic oil from the annular passage 24.
During this time, the inside of the torque converter 1, that is, the inside of the converter chamber 17, is maintained at a constant pressure PC by a pressure holding valve (not shown) provided in the subsequent hydraulic oil passage.

The lock-up control chamber 18 communicates with the communication port 25a of the lock-up control valve 25 through the hollow hole 11a of the torque converter output shaft 11, and this control valve is connected to a shaft 25b, a plug 25c, and a spring that urges these rightward in the figure. It consists of 25d and 25e. The lock-up control valve 25 moves the spool 25b according to the governor pressure P _G corresponding to the vehicle speed supplied to the chamber 25f, and selectively connects the communication port 25a to the inlet port 25g, the drain port 25h with a fixed orifice 26, or the drain port 25i. The converter chamber pressure PC is introduced to the inlet port 25g.

The operation of the lock-up torque converter equipped with the slip control device of the present invention having the above-described structure will now be described.

When the vehicle speed is in the low converter region, the corresponding governor pressure P _G cannot push the spool 25b against the spring 25d, and the lock-up control valve 25 is in the first
Maintain the conditions shown in Figures and Figure 3. In this case, converter chamber pressure Pc is at ports 25g, 25a and hollow hole 1.
1a to the lockup control room 18,
Since this chamber 18 is brought to the same pressure as the converter chamber 17, the lock-up clutch 16 remains in the released position shown in FIG. 1, operating the lock-up torque converter in the converter condition. That is, the engine-driven pump impeller 2 directs hydraulic oil to the turbine runner 3, which then returns to the pump impeller 2 via the stator 4. During this time, the hydraulic oil rotates the turbine runner 3 with increasing torque under the reaction force of the stator 4, and this rotational power can be extracted from the torque converter output shaft 11 via the turbine hub 9, the pawl 15, and the sleeve 10.

On the other hand, when the vehicle speed is in the high lock-up region, the corresponding high governor pressure P _G can push the spool 25b not only against the spring 25d but also against the spring 25e, and the lock-up control valve 2
5 is in the state shown in FIG. In this case, the lockup control chamber 18 includes the hollow hole 11a and the port 25a.
The lockup clutch 16 is moved to the left in FIG. 1 by the converter chamber pressure Pc, and the clutch facing 16a is connected to the converter cover 5.
The lock-up torque converter is operated in the lock-up state by maintaining the joint position in pressure contact with the lock-up torque converter. That is, the engine rotation toward the pump impeller 2 does not pass through the torque converter 1, but passes through the lock-up clutch 16, the annular member 20, and the sleeve 10, and is directly extracted from the torque converter output shaft 11, thereby making the slip ratio of the torque converter zero. be able to.

When the vehicle speed is in the slip region between the above two values, the corresponding governor pressure P _G brings the lock-up control valve 25 into the state shown in FIG. 2. In this case, the pressure (lockup release pressure) P _L in the lockup control chamber 18 is extracted through the fixed orifice 26, while the pressure P _C from the converter chamber 17 is replenished through the variable orifice 19. Thus,
During this time, the pressure P _L in the lock-up control chamber 18 is determined by the opening degree of the variable orifice 19, and the lock-up clutch 16 is activated at a degree corresponding to this pressure P _L.
The converter cover 5 is frictionally coupled to the converter cover 5 while sliding, and power is transmitted in a slip control state intermediate between the converter state and the lock-up state.

Here, considering the force acting on the turbine hub 9, the frictional force between it and the ball 15 is slight, so if this is ignored, the turbine hub 9 has a generated torque as shown in FIG. (Transmission torque) The pressure difference between the force F _T due to T _T , the converter chamber pressure P _C and the lockup control chamber pressure P _L is the pressure difference in the chamber 12.
The pressure receiving area A of the turbine hub 9 (see Fig. 1)
The force F _L acting on the ball 15 is added to the ball 15.
has a drag force N that balances the resultant force of these forces. By the way, the above T _T and F _L are respectively F _T = T _T /R,...(1), F _L = (P _C - P _L ) x A... (2)
In the balanced state, F _T and F _L are also expressed by F _T =N sin θ and F _L = N cos θ, respectively, so the relational expression F _L tan θ = F _T (3) can be determined.

The transmission torque T _L of the lockup clutch 16 is expressed by the formula T _L = K (P _C - P _L ) (4), where K is a constant determined by its pressure receiving area and radius. From equations (1) to (3) above, T×A/Ktanθ=T _T /R can be found, and as a result, between T _L and T _T , T _L =K/A×1/Rtanθ×T _T The relational expression is established. In this formula, K, A, and R are fixed values, so K/A×1/R in the above formula is a constant,
If this is replaced with α, the above equation becomes T _L =α×T _T /tanθ (5).

From the above equation (5), the lockup clutch transmission torque T _L and the turbine runner transmission torque T _T are expressed by a function with θ as a parameter, and as is clear from the above, the relationship θ (x) where θ is x Therefore, T _L and T _T that change during time t are respectively T _L (t),
When T _T (t), the above equation (5) can be rewritten as T _L (t)·tanθ(x)=αT _T (t).

Control deviation Δ between stable slip control T _L and T _T [Δ=T _L (t)・tanθ(x)−αT _T (t)]
becomes zero, and the lockup clutch transmission torque T _L and the turbine runner generated torque T _T are balanced at a ratio determined by the angle θ at this time. In addition,
The position of the ball 15 at this time, therefore the flange 9a
(turbine runner 3) and flange 10a (lock-up clutch 16), and hole 9.
The following explanation will be developed assuming that the overlaps of b and 10d are as shown in FIGS. 5 and 7, respectively.

From this balanced state, the turbine runner transmission torque _{T T} increases due to an increase in the engine throttle opening.
If the slip amount of the torque converter increases from the stable state, the control deviation Δ changes from zero to _-αΔTT . At this time, the turbine hub 9
(Flange 9a) is the sleeve 10 (Flange 10
With respect to a), the opening S of the variable orifice 19 is decreased by relative displacement (relative rotation) in the direction of advance in the rotational direction shown by the solid line arrow in FIGS. 5 and 7. Because of this,
The pressure flowing from the converter chamber 17 to the lockup control chamber 18 decreases, and the lockup release pressure P
As a result of the decrease in _L , the coupling force of the lockup clutch 16 increases, and feedback control is performed so that the transmitted torque matches _ΔTT , that is, the deviation Δ becomes zero.

The above slip control can be expressed as follows. When the lockup clutch transmission torque in the initial balance state is T _Li and the turbine runner transmission torque is T _Ti , the deviation Δ is expressed by the following equation and becomes zero.

Δ=T _Li tanθ(x)−αT _Ti =0... The deviation Δ when the slip increases when the torque T _Ti increases by ΔT _T is expressed by the following equation.

Δ=T _Li tanθ(x)−α(T _Ti +ΔT _T ) =−αΔT _T ... Let ΔT _L be the increment due to feedback control (increase) of the lock-up clutch transmission torque T _L that returns Δ to zero, and the point x of X (see Figure 6)
When the amount of axial displacement is Δx, the deviation Δ is expressed by the following formula, Δ=(T _Li +ΔT _L )tanθ(x+Δx) −α(T _Ti +ΔT _T )... The torque T is adjusted so that this deviation becomes zero. Feedback control of _L is performed, and the ratio of the lockup clutch transmission torque T _L to the turbine runner transmission torque T _T is returned to the constant value in the balanced state.

In the above equation, the ball displacement amount Δx is the feedback amount to make the deviation Δ zero, but as mentioned above, since the hole groove bottom surfaces 13a and 14a are inclined so that dθ/dx>0, the lock-up clutch As the relative displacement of the variable orifice 16 and the turbine runner 3 in the variable orifice closing direction increases, the feedback amount Δx decreases. Therefore, the slip control described above is executed stably, the lock-up release pressure P _L does not greatly hunt as shown in Fig. 9, and the engine speed is approximately the same as the torque converter output shaft speed. Not only is it more stable, but it also prevents the engine from generating humming noise and vibrations due to lack of slip.

Conversely, from the balanced state, when the turbine runner transmission torque T _T becomes too small by ΔT _T due to a decrease in the engine throttle opening, and the slip amount of the torque converter decreases from the stable state, the deviation Δ changes from zero to αΔT _T becomes. At this time, the turbine hub 9 (flange 9a) is connected to the sleeve 10 (flange 10a).
5 and 7, the opening degree S of the variable orifice 19 is increased. As a result, more pressure flows from the converter chamber 17 to the lockup control chamber 18, and the lockup release pressure P _L increases. As a result, the coupling force of the lockup clutch 16 decreases, so that the transmitted torque matches ΔT _T .
In other words, feedback control is performed so that the deviation Δ becomes zero, and the ratio between the lockup clutch transmission torque T _L and the turbine runner transmission torque T _T is returned to the constant value in the balanced state.

The slip control during deceleration is +Δ in the above formula.
T _L is -ΔT _L , +Δx is -Δx, +ΔT _T is -ΔT _T
The lock-up clutch transmission torque T _L is reduced so that the deviation Δ expressed by the equation replaced by is small, and slip control can be performed stably without occurrence of hunting.

(6) Effects of the invention As described above, the present invention provides the ball groove bottom surface 1.
The inclination angle θ of 3a and 14a is changed as the relative displacement (relative rotation in the illustrated example, but axial relative movement is also possible) of the output element 3 and lockup clutch 16 in the closing direction of the variable orifice 19 progresses. Since the ratio of the relative displacement to the change in torque difference is selected to decrease (dθ/dx>0 in the illustrated example), the feedback amount (Δx in the illustrated example) with respect to the slip amount deviation is always appropriate and stable. can perform slip control,
It is possible to prevent engine humming noise and vibration from occurring due to the hunting.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional side view of a lock-up torque converter equipped with the slip control device of the present invention, FIGS. 2 to 4 are explanatory diagrams of the functions related to the lock-up control valve of the torque converter, and FIG. 5 is the same as that shown in FIG. 1. Figure 6 is a developed cross-sectional view on the - line of Figure 5.
Fig. 7 is a plan view of the variable orifice seen in the direction of the arrow in Fig. 1, Fig. 8 is an opening change characteristic diagram of the variable orifice,
Fig. 9 is an operation time chart of the lock-up torque converter according to the present invention; Fig. 10 is an exploded sectional view similar to Fig. 5 showing the cam mechanism of the slip control device previously proposed by the applicant; and Fig. 11. 12 is a time chart showing the response delay of the lockup release pressure to a change in the variable orifice opening, and FIG. 12 is an operation time chart of the lockup torque converter using the slip control device previously proposed by the applicant of the present application. 1... Torque converter, 2... Pump impeller (torque converter input element), 3... Turbine runner (torque converter output element), 4...
Stator, 5... Converter cover, 9... Turbine hub, 9a... Hub flange, 9b... Hole (variable orifice), 10... Sleeve, 10a...
...Sleeve flange, 10b, 10c, 10d...
...hole (10d...variable orifice), 10e...
Teeth, 11...Torque converter output shaft, 12...
Pressure chamber, 13, 14...Pole groove (cam mechanism),
13a, 14a... Pole groove bottom (cam mechanism),
15... Pole (cam mechanism), 17... Converter chamber, 18... Lockup control room, 19... Variable orifice, 20... Annular member, 20a...
Teeth, 21...One-way clutch, 22...Hollow fixed shaft, 25...Lock-up control valve, 26...Fixed orifice, S...Variable orifice opening degree.

Claims (1)

[Claims] 1 comprising an input/output element and a lockup clutch that limits the slip between these input/output elements in response to the differential pressure between the converter chamber and the lockup control chamber, the output element being coupled to the lockup clutch; A cam mechanism consisting of opposed ball grooves and balls interposed between these ball grooves drives and connects the output element and the lockup clutch so that they can be relatively displaced according to the difference in transmitted torque, and the relative displacement changes the opening degree. In the lock-up torque converter, the lock-up torque converter is provided with a variable orifice that can control the slip by adjusting the degree of communication between the converter chamber and the lock-up control chamber. and the rotating surface of the lock-up torque converter is selected such that as the relative displacement of the variable orifice in the closing direction progresses, the ratio of the relative displacement to the change in the transmission torque difference decreases. slip control device.