JP4070435B2 - Oil quantity balance control device for forward / reverse switching mechanism of continuously variable transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an oil amount balance control device in which a friction element in a forward / reverse switching mechanism of a continuously variable transmission does not cause a shortage of oil when a high load is selected.
[0002]
[Prior art]
A continuously variable transmission has a forward / reverse switching mechanism at the front stage or the rear stage (usually the front stage) of the continuously variable transmission mechanism because the continuously variable transmission mechanism does not have a function of switching the rotation direction by itself, and the forward friction within the continuously variable transmission mechanism. An element (clutch or brake) or a reverse friction element (clutch or brake) is engaged so that the continuously variable transmission can be set in a forward rotation transmission state or a reverse rotation transmission state.
[0003]
As a hydraulic circuit for engaging and releasing the forward friction element or the reverse friction element, the excess oil from the line pressure control valve for controlling the line pressure used for the shift control of the continuously variable transmission mechanism is used as the clutch original pressure control valve. The pressure is controlled by this, whereby the forward friction element or the reverse friction element of the forward / reverse switching mechanism is fastened or released.
[0004]
By the way, the line pressure is, for example, described for a V-belt type continuously variable transmission, and is used to transmit torque from the prime mover by pressing the V-belt between pulley V-groove side walls when used for shift control. Therefore, it is necessary to match the load condition of the motor. Otherwise, when the line pressure (transmission torque capacity) is excessive, excessive tension is applied to the V-belt, and the line pressure (transmission torque capacity) ) Is insufficient, the V-belt is slipped, and in any case, durability is lowered.
[0005]
On the other hand, the clutch original pressure for fastening the forward friction element and the reverse friction element in the forward / reverse switching mechanism also matches the load state of the prime mover because the transmission torque capacity of these friction elements is determined. Otherwise, a large select shock occurs when the clutch base pressure (transmission torque capacity) is excessive, and a large select response delay occurs when the clutch (transmission torque capacity) is insufficient.
[0006]
Therefore, conventionally, as described in, for example, Japanese Patent Application Laid-Open No. 8-210449, when the prime mover is in a high load state at the time of selection, the target value of the line pressure is higher than that at the low load, up to a limit value that does not cause belt slip. A technology to enhance was proposed.
[0007]
[Problems to be solved by the invention]
When such a conventional technique is applied to the above-described line pressure control system and clutch source pressure control system, when the accelerator pedal is depressed within a predetermined time after the selection operation from the non-traveling range to the traveling range, at the time of high load selection. To explain, the line pressure target value is increased from the moment of depression to the ultimate line pressure for high load, and the actual line pressure is controlled to increase along this.
[0008]
However, in the above-described line pressure control system and clutch source pressure control system, excess oil discharged from the line pressure control valve after the line pressure control valve has been controlled to increase the line pressure as described above is used as the clutch source pressure. High load selection that rapidly increases the line pressure because the pressure is adjusted by the control valve to generate the clutch original pressure, which is supplied to the forward friction element and the reverse friction element to generate the engagement pressure (clutch pressure). At times, the clutch base pressure drops significantly due to insufficient oil amount.
[0009]
For this reason, the fastening delay of the friction element occurs, and the engine speed also increases during this period due to the high load. Therefore, the forward friction element and the reverse friction element are suddenly caused by the clutch pressure increased after the increase of the engine speed. Will be concluded.
As a result, vibration of the torque transmission system is induced to cause a peak torque exceeding the allowable limit torque to act on the V belt, thereby reducing the durability of the V belt and causing a shock.
[0010]
However, if a large-capacity oil pump is used to satisfy the oil amount balance so that the clutch original pressure Pco is generated as specified even when the high load is selected, the driving load of the pump increases and the fuel consumption is reduced. It is accompanied by deterioration, and if it is attempted to satisfy the oil amount balance by reducing the amount of oil leakage, the cost increases and it is not practical.
[0011]
The present invention determines a region where the oil amount balance of the forward / reverse switching control unit is not established at the time of high load selection by the line pressure limit value, and prevents the line pressure from increasing beyond this limit value. The oil amount balance of the forward / reverse switching control unit on the downstream side of the control can be reliably established,
Therefore, the oil amount balance in the forward / reverse switching mechanism of the continuously variable transmission mechanism that can avoid the fastening delay of the forward friction element and the reverse friction element as described above, and the occurrence of the peak torque and shock associated therewith can be avoided. The purpose is to propose a control device.
[0012]
[Means for Solving the Problems]
For this purpose, an oil amount balance control device for a continuously variable transmission according to the first aspect of the present invention comprises:
In the continuously variable transmission in which the excess oil from the line pressure control valve that controls the line pressure used for the shift control of the continuously variable transmission mechanism is controlled by the clutch source pressure control valve and used for the control of the forward / reverse switching mechanism.
If the prime mover is in a high load state when selecting from the non-travel range to the travel range, the clutch pressure control valve can produce a predetermined pressure, the line pressure limit value on the oil amount balance, and when the high load is selected The line pressure control valve is configured such that the lower one of the line pressure target value is the pressure regulation value of the line pressure control valve.
[0013]
In the invention of claim 2, the line pressure limit value in the invention of claim 1 is set to a smaller value as the rotational speed of the oil pump that discharges hydraulic oil that is a medium of the line pressure and the clutch original pressure is lower. It is a thing.
[0014]
Further, the invention of claim 3 is such that the line pressure limit value in the invention of claim 1 or 2 is set to a smaller value as the oil temperature of the hydraulic oil that is the medium of the line pressure and the clutch original pressure is higher. is there.
[0015]
【The invention's effect】
In claim 1, the surplus oil from the line pressure control valve that controls the line pressure for continuously variable transmission control is pressure-controlled by the clutch original pressure control valve and used for controlling the forward / reverse switching mechanism.
At this time, if the prime mover is in a high load state during selection from the non-travel range to the travel range, the clutch pressure control valve can produce a predetermined pressure, the line pressure limit value on the oil amount balance, and the high load The lower one of the line pressure target value at the time of selection is set as the pressure adjustment value of the line pressure control valve.
Therefore, at the time of high load selection, the line pressure does not increase beyond the line pressure limit value that makes it impossible to establish the oil amount balance of the forward / reverse switching control unit, and the forward / reverse switching control on the downstream side of the line pressure control The oil amount balance of the head portion can be established reliably, thereby avoiding the problem of the fastening delay of the forward friction element and the reverse friction element as described above, and the occurrence of peak torque and shock associated therewith. .
[0016]
In claim 2, since the line pressure limit value in the invention of claim 1 is made smaller as the rotational speed of the oil pump is lower,
In line with the fact that the line pressure limit value, which makes it impossible to establish the oil amount balance of the forward / reverse switching control unit, becomes smaller as the oil pump speed decreases, the line pressure under any oil pump speed Can be limited to the minimum necessary.
[0017]
In claim 3, since the line pressure limit value in claim 1 or 2 is set to a smaller value as the hydraulic oil temperature is higher,
In line with the fact that the line pressure limit value, which makes it impossible to establish the oil amount balance of the forward / reverse switching control unit, becomes smaller due to leakage as the oil temperature rises, the line pressure can be adjusted under any oil temperature. It can be limited to the minimum necessary.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 to 4 show an example in which an oil amount balance control device according to an embodiment of the present invention is applied to a V-belt type continuously variable transmission.
[0019]
FIG. 1 shows a transmission system of the same V-belt type continuously variable transmission configured as a transaxle. This transmission system includes an input shaft 3 that receives rotation from an engine 1 as a prime mover via a torque converter 2, and It comprises a forward / reverse switching mechanism 4, a V-belt transmission mechanism 5, and a differential gear device 6.
The forward / reverse switching mechanism 4 includes a double pinion planetary gear set 7 and can transmit the rotation of the input shaft 3 to the V-belt transmission mechanism 5 as it is when the forward clutch 8 is engaged. 3 is reversely transmitted to the V-belt transmission mechanism 5.
[0020]
The V-belt transmission mechanism 5 includes a drive-side primary pulley 10 to which rotation from the forward / reverse switching mechanism 4 is input, a driven-side secondary pulley 11, and a V-belt 12 that spans between these pulleys 10 and 11. Constitute.
Here, each of the primary pulley 10 and the secondary pulley 11 rotates one flange 10a, 11a together with the other flange 10b, 11b, but is a movable flange that can be displaced in the axial direction, and the position of these movable flanges 10a, 11a is a cylinder. Control is possible by the pressure in the chambers 10c and 11c.
[0021]
The V-belt transmission mechanism 5 sequentially transmits the rotation to the primary pulley 10 to the secondary pulley 11 and the output shaft 13 via the V-belt 12.
This transmission in the secondary pulley cylinder chamber 11c, to supply the line pressure P _L, which is controlled by the system of FIG. 2, the primary pulley cylinder chamber 10c, (not shown) the shift control valve as source pressure line pressure P _L Is supplied with the shift control pressure (primary pulley pressure) determined.
Then, by the ratio of the primary pulley pressure in the primary pulley cylinder chamber 10c to the line pressure _{P L} in the secondary pulley cylinder chamber 11c, and determines the moving flange 10a, the position of 11a, wrapping the V belt 12 with respect to the pulleys 10 and 11 The arc diameter, that is, the transmission ratio (transmission ratio) between pulleys is determined.
[0022]
Therefore, the V-belt transmission mechanism 5 can increase the primary pulley pressure to change the gear ratio continuously from the lowest speed gear ratio toward the high speed gear ratio in a stepless manner. By reducing the gear ratio, the gear ratio can be continuously changed in a stepless manner continuously toward the lowest speed gear ratio.
[0023]
The rotation from the V-belt transmission mechanism 5 to the output shaft 13 is input to the differential gear device 6 via the parallel shaft gear set 14, and the differential gear device 6 is driven to the left and right of the vehicle (not shown) via the axles 15 and 16. The wheels shall be driven differentially.
[0024]
Figure 2 is entered into a forward clutch 8 and the reverse brake 9 pressure Pc, ON of Pb, fastened by OFF, the hydraulic circuit to release control, shown with the control circuit of the line pressure P _L, the hydraulic fluid is a medium of pressure An oil pump 22 for sucking and discharging from the oil pan 21 is provided.
The oil pump 22 is driven by the engine 1, the discharge oil from the oil pump 22, the shift control unit of the V-belt transmission mechanism 5 are pressure adjusted to a predetermined line pressure P _L by the line pressure control valve 23 (see FIG. 1) Heading to 24, it is used for the shift control.
[0025]
Surplus oil remaining during the above-described line pressure control by the valve 23 is sent from the valve 23 to the circuit 25, and the clutch source pressure control valve 26 uses the excess oil as a medium to convert the excess oil in the circuit 25 to a predetermined clutch source pressure Pco. Adjust pressure.
The line pressure control valve 23 and the clutch source pressure control valve 26 are responsive to the control pressure Ps generated by the solenoid valve 28 according to the duty D based on a constant pilot pressure from the control source pressure generator 27, and the line pressure P _L and the clutch source pressure control Pco pressure Ps, i.e. the controls as illustrated according to FIG. 3, for example the solenoid valve drive duty D.
Incidentally, the line pressure _{P L} is changed to as shown in the drawing between the minimum value _{P LMIN} and a maximum value _{P LMAX} corresponding to the solenoid valve drive duty D, the minimum value _{P CMIN} clutch source pressure Pco is according to the solenoid valve drive duty D and it shall be changed as shown in the drawing between the maximum value P _CMAX.
[0026]
The clutch original pressure Pco is supplied to the forward / reverse switching valve 31.
The forward / reverse switching valve 31 supplies the clutch original pressure Pco to the forward clutch 8 in the forward range to generate the engagement pressure Pc, and drains the engagement pressure Pb of the reverse brake 9,
In addition, the clutch original pressure Pco is supplied to the reverse brake 9 in the reverse range to generate the engagement pressure Pb, and the engagement pressure Pc of the forward clutch 8 is drained.
Further, it is assumed that both the engagement pressure Pc of the forward clutch 8 and the engagement pressure Pb of the reverse brake 9 are drained in a state where the clutch original pressure Pco is shut off in the parking / stopping range.
[0027]
The accumulators 34 and 35 are connected to the engagement pressure circuit 32 of the forward clutch 8 and the engagement pressure circuit 33 of the reverse brake 9, respectively. And the clutch original pressure Pco acts as an accumulator back pressure in a direction opposite to this.
Thus, the accumulators 34 and 35 can transiently control the corresponding engagement pressure Pc of the forward clutch 8 and the engagement pressure Pb of the reverse brake 9 according to the clutch original pressure Pco applied as the accumulator back pressure.
[0028]
By the way, in the present embodiment, the line pressure P _L is set by executing the control program shown in FIG. 4 in order to achieve the oil amount balance in the control system of the forward clutch 8 and the reverse brake 9 targeted by the present invention. The control is performed as shown in FIG.
Control program in FIG. 4 is a controller 41 shown in FIG. 2, and controls the line pressure P _L through the duty control of the solenoid valve 28, the controller 41, detects the selected range of the V-belt type continuously variable transmission The range signal from the inhibitor switch 42, the signal from the engine rotation sensor 43 that detects the engine speed Ne, the signal from the throttle opening sensor 44 that detects the engine throttle opening TVO, and the vehicle speed that detects the vehicle speed VSP. A signal from the sensor 45 and a signal from the oil temperature sensor 46 that detects the hydraulic oil temperature TMP are input.
[0029]
The controller 41 is repeatedly executed by a regular interrupt at regular intervals. First, the selection range is read in step S51, and whether or not there is a selection from the non-traveling range to the traveling range in step S52 based on this. Determine.
When it is determined in step S52 that there is a selection from the non-traveling range to the traveling range, in step S65, the selection timer for measuring the elapsed time from the selection is reset and started, and in step S53, the high load determination is performed. The throttle opening TVO, the engine speed Ne, and the vehicle speed VSP are read.
[0030]
In step S54, when the throttle opening TVO, the engine speed Ne, and the vehicle speed VSP are all less than the set value, it is determined that the load is low.
When it is determined that the load is high in step S54, it is during the high load selection, so the hydraulic oil temperature TMP is read in step S55, and then in step S56, the hydraulic oil is obtained based on the map of FIG. From the temperature TMP and the engine rotational speed Ne (oil pump rotational speed), the line pressure limit value P _LLIM on the oil amount balance that the clutch original pressure control valve 26 can produce a predetermined pressure at the time of high load selection is _obtained by searching. .
[0031]
Here, the line pressure limit value P _LLIM is changed according to the engine speed Ne (oil pump speed) with the hydraulic oil temperature TMP as a parameter, as shown in FIG. Since the above oil amount balance becomes strict, the line pressure limit value P _LLIM is made smaller as the temperature is _higher, and the lower the engine speed Ne (oil pump speed) is, the lower the oil amount balance becomes. The line pressure limit value P _LLIM is decreased as the engine rotates.
[0032]
In the next step S64, determined by the line pressure target value P _LO at high load selector as shown in Figure 5, for example.
In step S71 of FIG. 5, it is checked whether or not the high load select flag has already been set. If it has not been set, the high load select flag is set in step S72 to indicate that the high load select is being performed. In step S73, the high load timer is reset and started in order to measure the elapsed time from the time of the high load selection (accelerator stepping instant after the selection).
If it is determined in step S71 that the high load select flag has already been set, steps S72 and S73 are unnecessary and are not executed by skipping them.
[0033]
In the next step S74 and step S75, it is determined whether or not the select timer activated in step S65 in FIG. 4 is less than the set time a, and whether the high load timer activated in step S73 in FIG. 5 is less than the set time b. Check whether or not.
If the high-load timer is less than the set time b while the select timer is less than the set time a or more than the set time a, the line pressure target value P _LO at the time of high load is selected in step S76. A constant initial pressure lower than the control maximum value (final hydraulic pressure), which is the final target at the time of high load selection, is commanded.
[0034]
After the moment when it is determined in step S74 that the select timer has reached the set time a or more and in step S75 it is determined that the high load timer has become the set time b or more, in step S77, the line pressure target at the time of high load select is determined. It is checked whether or not the first hydraulic pressure inclination flag indicating that the control for increasing the value P _LO with a gentle first gradient is being performed has been set. If it has not been set yet, in step S78, from that instant. launch resets the first hydraulic gradient timer for measuring an elapsed time, already skips step S78 if set, it advances the control to step S79, where a high load select line pressure target value P _LO The first hydraulic pressure inclination flag is set to indicate that the ascent at the first gradient has started.
[0035]
In the next step S80, it is checked whether or not the first hydraulic pressure inclination timer is less than the set time c. Until the set time c elapses, in step S81, the line pressure target value P _LO at the time of high load selection is set to the above-described value. The hydraulic pressure value is commanded so as to rise from the initial pressure at a relatively gentle first gradient.
In step S80, when determined that the first hydraulic gradient timer is more than the set time c, the control maximum high load select line pressure target value P _LO at step S82 is a final goal of high load selector As long as it is determined that the value is lower than the reached hydraulic pressure _{PLmax, the} hydraulic pressure value is commanded in step S83 so as to increase to the high load select line pressure target value _PLO with a relatively steep second gradient.
[0036]
After high load select line pressure target value P _LO is determined to have reached the control maximum value a is reached hydraulic P _Lmax an ultimate goal of high load selection at step S82, the in step S84, the high load The ultimate oil pressure P _Lmax is commanded to the line pressure target value P _LO during selection.
As described above, after the high load selection line pressure target value _PLO is determined in step S76, step S81, step S83, or step S84, the control returns to step S57 in FIG.
[0037]
In this step S57, the line pressure limit value P _LLIM obtained in step S56 is compared with the high load select line pressure target value P _LO obtained in step S64, and if P _LLIM ≧ P _LO , the line pressure command is issued in step S58. sets the value _{P L} to the line pressure target value _{P LO,} sets the _P LLIM _{<P LO} if the step S59 in the line pressure command value line pressure limit value _{P Llim} to _{P L.}
[0038]
When it is determined in step S52 that there is no selection from the non-traveling range to the traveling range, the high load selection flag is reset in step S66, the first hydraulic pressure inclination flag is reset in step S67, setting the non-select line pressure to the line pressure command value P _L in S60.
[0039]
When it is determined in step S54 that the load is not high, the high load select flag is reset in step S68, the first hydraulic pressure inclination flag is reset in step S69, and then in step S61, the example illustrated in FIG. calculated by searching a low load select line pressure from the transmission ratio and input torque based on the map corresponding to the characteristic, and sets the low load select line pressure to the line pressure command value P _L.
After determining the line pressure command value P _L to as described above in step S58~ step S61, the solenoid drive duty D for causing achieve the line pressure command value P _L calculated in step S62, then in step S63 This duty D is output to the solenoid valve 28 (see FIG. 2).
[0040]
According to the above control, when the high load is selected, the lower one of the line pressure _limit value P _LLIM and the line pressure target value P _LO is set to the pressure regulation value P _L of the line pressure control valve 23 (see FIG. 2). That is, the control is performed so that the line pressure does not become an oil amount balance non-established region on the higher line pressure side than the characteristic line of the line pressure _limit value PLLIM shown in FIG.
[0041]
Therefore, referring to FIG. 8 showing an operation time chart at the time of high load selection, the line pressure command value P _L is not the line pressure target value P _LO but the line pressure limit value P _LLIM in the hatched region where P _LLIM <P _LO. Limited.
Therefore, the clutch source pressure by applying regulated by the surplus oil clutch source pressure control valve 26 to the line pressure control valve 23 is discharged from the line pressure control valve 23 after controlling the line pressure P _L to the circuit 25 as shown in FIG. 2 Pco ungated, even hydraulic circuit using this engagement control of the forward clutch 8 and the reverse brake 9, that the clutch source pressure Pco at high load selection to increase the line pressure P _L is significantly reduced by the oil amount shortage Such a thing disappears.
[0042]
Therefore, as is apparent from the waveform related to the transmission torque Ti of the forward clutch 8 or the reverse brake 9 with and without vibration, the engagement delay of these friction elements can be eliminated, and after the engine speed Ne increases. Since the forward clutch 8 or the reverse brake 9 is not suddenly engaged, the peak torque exceeding the allowable limit torque Lim can be prevented as shown in FIG. It is possible to solve the above-mentioned problems such as inviting and shocking.
[0043]
In the present embodiment, as illustrated in FIG. 7, the line pressure limit value P _LLIM is set to a smaller value as the oil pump speed (engine speed Ne) is lower, and the hydraulic oil temperature TMP is higher. Because it was set to a small value,
_Any oil in line with the fact that the line pressure limit value _{PLLIM, which} makes it impossible to establish the oil quantity balance of the forward / reverse switching control unit, becomes smaller as the oil pump rotational speed is lower and as the oil temperature is higher. The line pressure can be limited to the minimum necessary under the pump rotation speed and at any oil temperature, and the influence of the restriction can be almost eliminated.
[0044]
In the above description, the automatic transmission is a V-belt type continuously variable transmission. However, the present invention is similarly applied to other types of continuously variable transmissions such as a toroidal type continuously variable transmission, and has the same effect. It goes without saying that can be achieved.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a transmission system of a V-belt type continuously variable transmission including an oil amount balance control device during high load selection according to an embodiment of the present invention.
FIG. 2 is a hydraulic circuit diagram showing a forward / reverse switching hydraulic system for the V-belt continuously variable transmission.
FIG. 3 is a diagram showing the relationship between solenoid drive duty, line pressure, and clutch source pressure in the system.
FIG. 4 is a flowchart showing a control program executed by a controller of the oil amount balance control apparatus according to the embodiment;
FIG. 5 is a flowchart showing a subroutine related to processing for obtaining a line pressure target value at the time of high load selection in the control program.
FIG. 6 is a change characteristic diagram of a low load line pressure used for obtaining a line pressure at the time of low load selection in the control program.
FIG. 7 is a diagram showing a line pressure limit value at which the oil amount balance of the forward / reverse switching mechanism control unit in the hydraulic circuit is established.
FIG. 8 is an operation time chart showing an oil amount balance control operation at the time of high load selection according to the same embodiment.
[Explanation of symbols]
1 engine (motor)
2 Torque converter 3 Input shaft 4 Forward / reverse switching mechanism 5 V-belt transmission mechanism 6 Differential gear device 7 Planetary gear set 8 Forward clutch 9 Reverse brake
10 Primary pulley
10a Movable flange
11 Secondary pulley
11a Movable flange
12 V belt
13 Output shaft
21 Oil pan
22 Oil pump
23 Line pressure control valve
24 V-belt type continuously variable transmission control unit
26 Clutch source pressure control valve
27 Control source pressure generator
31 Forward / reverse selector valve
34 Accumulator
35 Accumulator
41 Controller
42 Inhibitor switch
43 Engine rotation sensor
44 Throttle opening sensor
45 Vehicle speed sensor
46 Oil temperature sensor

Claims (3)

In the continuously variable transmission in which the excess oil from the line pressure control valve that controls the line pressure used for the shift control of the continuously variable transmission mechanism is controlled by the clutch source pressure control valve and used for the control of the forward / reverse switching mechanism.
If the prime mover is in a high load state when selecting from the non-travel range to the travel range, the clutch pressure control valve can produce a predetermined pressure, the line pressure limit value on the oil amount balance, and when the high load is selected An oil amount balance control device for a forward / reverse switching mechanism of a continuously variable transmission, wherein the line pressure control valve has a lower pressure value as a pressure regulation value. 2. The continuously variable transmission according to claim 1, wherein the line pressure limit value is set to a smaller value as the rotational speed of an oil pump that discharges hydraulic oil that is a medium of line pressure and clutch original pressure is lower. Oil quantity balance control device for the forward / reverse switching mechanism. 3. The forward / reverse travel of a continuously variable transmission according to claim 1, wherein the line pressure limit value is set to a smaller value as the temperature of hydraulic oil as a medium of the line pressure and the clutch base pressure is higher. Oil quantity balance control device in switching mechanism.

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