JP6946025B2 - Stepped transmission control device - Google Patents

Description

The present invention relates to a control device for a stepped transmission that applies a precharge pressure when engaging friction engaging elements to reduce backlash.

A friction engagement element that switches from an released state to an engagement state in a stepped transmission that achieves a desired shift by selectively engaging a plurality of friction engagement elements (clutch or brake) by operating hydraulically. There is known a technique for eliminating the dead zone of the clutch by applying a precharge pressure to the oil chamber that drives the engagement piston to fill the backlash.

Further, when the precharge pressure is generated by using the line pressure as the original pressure, if the line pressure decreases, a predetermined precharge pressure cannot be generated. In this case, the precharge pressure depends on the degree of decrease in the line pressure. Also disclosed is a technique for lowering the pressure of the first fill control and lengthening the time accordingly (Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-173641

By the way, in a stepped transmission for a vehicle, the line pressure may be significantly higher than the precharge pressure depending on the running condition of the vehicle. In this case, even if a predetermined precharge pressure is applied to the oil chamber. It has been found that the backlash filling of the friction engaging element may not be completed without obtaining a predetermined flow rate.

The present invention was devised in view of such a problem, and the backlash of the friction engaging element is completed by applying the precharge pressure to the oil chamber even when the line pressure becomes significantly higher than the precharge pressure. It is an object of the present invention to provide a control device for a stepped transmission capable of being operated.

(1) In order to achieve the above object, the control device for the stepped transmission of the present invention includes a hydraulic control unit that supplies pressure to the oil chamber of the friction engaging element for establishing the shift stage, and the hydraulic pressure. In the control device of the stepped transmission provided with the control means for controlling the control unit, the hydraulic control unit has a regulator valve that generates a line pressure and the oil of the friction engagement element using the line pressure as a source pressure. A pressure adjusting valve for adjusting the pressure supplied to the chamber is provided, and the control means sets the pressure adjusting valve on the friction engaging element for switching from the released state to the engaged state based on the precharge pressure reading value. It is a control that controls and precharges the oil chamber to close the backlash of the friction engaging element. At the start of the control, the precharge pressure is gradually increased to the precharge pressure for a predetermined time, and then to the predetermined pressure. When the backlash filling control is performed and the backlash filling control is performed, the difference pressure between the line pressure and the preset precharge pressure indicated value is larger than a predetermined value. Is characterized in that the precharge pressure indicated value is upwardly corrected.

(2) It is preferable that the control means increases and corrects the precharge pressure higher as the differential pressure increases.
(3) It is preferable that the control means increases and corrects the precharge pressure indicated value based on the flow rate decrease characteristic with respect to the differential pressure.
(4) The regulator valve may be capable of changing the level of the line pressure.

According to the present invention, when the differential pressure between the line pressure and the preset precharge pressure indicated value is larger than a predetermined value, the precharge pressure indicated value is corrected to increase, so that the precharge pressure is pre-charged with respect to the line pressure. Even when the charge pressure is significantly small, it is possible to suppress the shortage of the flow rate of the oil to be precharged in the oil chamber and appropriately carry out the backlash filling.
The larger the differential pressure, the larger the shortage of the flow rate. However, by correcting the precharge pressure indicated value to be higher, the shortage of the oil flow rate can be appropriately compensated and the backlash can be packed more appropriately.

It is a block diagram which shows the vehicle which provided the stepped transmission which concerns on one Embodiment, and the control device of a stepped transmission. It is sectional drawing which shows the pressure adjustment valve which concerns on one Embodiment, (a) is an overall view, (b) is a partially enlarged view. It is a time chart which shows the characteristic of the precharge pressure by the control device of the stepped transmission which concerns on one Embodiment. It is a graph which shows the flow rate characteristic with respect to the line pressure and the precharge pressure of the stepped transmission which concerns on one Embodiment. It is a flowchart explaining the backlash packing control by the control device of the stepped transmission which concerns on one Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the embodiments shown below are merely examples, and there is no intention of excluding the application of various modifications and techniques not specified in the following embodiments. Each configuration of the following embodiments can be variously modified and implemented without departing from their gist, can be selected as necessary, or can be combined as appropriate.

[Vehicles equipped with stepped transmissions and stepped transmissions]
The stepped transmission according to this embodiment is applied to the drive system of a vehicle.
As shown in FIG. 1, the vehicle drive system includes an engine (internal combustion engine) 1 which is a vehicle drive source, a torque converter 2, a stepped automatic transmission mechanism 3, and a power transmission direction of the automatic transmission mechanism 3. A downstream power transmission system 4 and a drive wheel (not shown) downstream of the power transmission direction are provided. The stepped automatic transmission (stepped transmission) 10 is configured by housing the torque converter 2 and the automatic transmission mechanism 3 in the transmission case 10A.

The automatic transmission mechanism 3 achieves a plurality of forward stages and reverse stages. Each shift stage of the automatic transmission mechanism 3 is achieved by selectively engaging a plurality of friction engaging elements 31 such as a clutch or a brake. For example, when starting forward, the friction engaging element 31 that achieves the first speed is engaged, and when starting backward, the friction engaging element 31 that achieves the reverse stage is engaged. When traveling forward, the friction engaging element 31 that achieves the shift stage selected according to the vehicle speed and the engine load (here, the throttle valve opening degree) is engaged.

The engaging and disengaging states of each friction engaging element 31 are performed by adjusting the hydraulic pressure supplied to the friction engaging element 31 by hydraulic control through the respective hydraulic control valves 50. The hydraulic control valve 50 is a solenoid valve installed in the hydraulic control unit 5, and is operated by a command signal of an automatic transmission control unit (hereinafter, referred to as ATCU) 6 as a control means. This control device includes a hydraulic control unit 5 and an ATCU 6.

[Flood control valve]
The solenoid valve applied to the hydraulic control valve 50 can be applied to any of a linear solenoid and a duty solenoid, but here, the linear solenoid will be described as being applied.
The hydraulic control valve 50 adjusts the line pressure PL to a predetermined oil pressure by using the hydraulic oil of the hydraulic oil supplied from the oil pump 7 and adjusted to the line pressure PL by the pressure regulating valve (pressure regulator valve) 70 as the main pressure. Is supplied to the oil chamber (not shown) of the friction engaging element 31. Each friction engaging element 31 is adjusted to an engaging state according to the engaging hydraulic pressure (clutch pressure) supplied to the oil chamber.

As shown in FIG. 2A, for example, the hydraulic control valve 50 has a spool 52 movably inserted in the spool chamber 51 in the axial direction and a spool 52 in one of the axial directions (left side in the drawing). It includes an urging return spring 53 and a solenoid 54 that drives the spool 52 to the other axial direction (to the right in the figure) against the return spring 53.

In the spool chamber 51, an input port 51a into which the hydraulic oil of the original pressure (line pressure PL) is introduced, an output port 51b that outputs the hydraulic oil whose original pressure is adjusted, and a pressure adjustment output from the output port 51b. A feedback port 51c in which the subsequent hydraulic oil is introduced as a feedback pressure and drain ports 51d and 51e for discharging the hydraulic oil are formed.

The spool 52 includes land portions 52a, 52b, 52c formed at intervals from each other, and diameter-reduced portions 52d, 52e formed between the land portions 52a, 52b, 52c. The outer diameter of the land portion 52c is set to be smaller than that of the land portions 52a and 52b. The spool 52 moves in the axial direction to take a hydraulic oil supply position, a hydraulic oil discharge position, and a supply / discharge stop position.

The reduced diameter portion 52d between the land portions 52a and 52b communicates the input port 51a and the output port 51b when the spool 52 is in the hydraulic oil supply position, and the output port assumes that the spool 52 is in the hydraulic oil discharge position. The 51b and the drain port 51c are communicated with each other, and when the spool 52 is in the supply / discharge stop position, the communication between the input port 51a and the drain port 51c with respect to the output port 51b is cut off.

The solenoid 54 has a coil 54a and a plunger 54b, and is excited when a current is supplied to the coil 54a, and the plunger 54b is pressed against the spool 52 by magnetic force. As a result, when the current is not supplied to the coil 54a, the spool 52 takes the hydraulic oil discharge position, and when the current is supplied to the coil 54a, the spool 52 takes the supply / discharge stop position, and a larger current is supplied to the coil 54a. And the spool 52 take the hydraulic oil supply position.

When the spool 52 is in the hydraulic oil supply position, the space around the reduced diameter portion 52e between the land portions 52b and 52c communicates with the feedback port 51c and functions as a feedback hydraulic chamber 52f. When a feedback pressure (the oil pressure of the output port 51b) is introduced into the feedback hydraulic chamber 52f, this feedback pressure acts on the end face of the land portion 52b having a larger pressure receiving area than the end face of the land portion 52c, and the return spring 53 The spool 52 is urged in one axial direction against the urging force of the solenoid 54.

Therefore, when the solenoid 54 is supplied with the indicated current corresponding to the engaging hydraulic pressure to be supplied to the oil chamber of the friction engaging element 31, the solenoid 54 applies a predetermined urging force to the spool 52, and the spool 52 is subjected to the feedback pressure. It is adjusted to a position where the engagement hydraulic pressure can be output. As a result, the engagement hydraulic pressure can be adjusted linearly.

[Rattling control]
By the way, in ATCU 6, the frictional engagement element 31 that switches from the released state to the engaged state is precharged (pre-supplied) with hydraulic oil to the oil chamber as a preparatory step for the engagement switching, and is frictionally engaged. Performs backlash control to reduce backlash of elements.

In this backlash filling control, for example, the engagement hydraulic pressure is controlled by the indicated pressure Pd shown by the thick solid line in FIG. That is, at the start of control, the engagement hydraulic pressure is first stepped up to a predetermined pressure (precharge shelf pressure, also simply referred to as precharge pressure) Pa for a predetermined time (very short time), and then the predetermined pressure is increased. Reduce to Pb. As a result, hydraulic oil is supplied into the oil chamber of the friction engaging element 31 with a flow rate characteristic as shown by a fine solid line in FIG.

Since there is a wasted time (response delay) in the rise of the oil pressure with respect to the indicated pressure Pd of the precharge pressure Pa, the flow rate of the hydraulic oil supplied to the oil chamber is relative to the indicated pressure Pd of the precharge pressure Pa. It stands up with this response delay. At this time, the flow rate of the hydraulic oil supplied to the oil chamber is usually large according to the magnitude of the precharge pressure Pa. When the indicated pressure Pd is reduced from the precharge pressure Pa to the predetermined pressure Pb, the flow rate of the hydraulic oil supplied to the oil chamber also decreases with a delay. By applying the precharge pressure Pa that is raised in a stepwise manner, the hydraulic oil is quickly supplied to the oil chamber, and the backlash of the friction engaging element is achieved.

However, the friction engaging element must not be engaged by the backlash of the friction engaging element, and it is necessary to carry out the backlash of the friction engaging element within the range where the friction engaging element is not engaged. Therefore, by setting the height h of the precharge pressure Pa and the time t for giving the precharge pressure Pa, the friction engaging element engages with the amount of hydraulic oil supplied to the oil chamber corresponding to the integrated value of the flow rate. I am trying to be in the state just before.

However, it has been found that even if a predetermined precharge pressure is applied to the oil chamber, a predetermined flow rate may not be obtained and the backlash of the friction engaging element may not be completed. It was also found that this situation occurs when the differential pressure between the line pressure and the precharge pressure becomes significantly large. When the line pressure can be changed, the line pressure may be significantly increased depending on the traveling condition of the vehicle, and the precharge pressure also changes depending on the friction engaging element of the target and the traveling condition of the vehicle. As a result, depending on the traveling state of the vehicle, the line pressure may be significantly higher than the precharge pressure, and there is a problem that a predetermined flow rate cannot be obtained even if a predetermined precharge pressure is applied.

FIG. 4 is a graph showing the flow rate characteristics with respect to the line pressure PL and the precharge pressure Pa based on the test results for a certain friction engaging element. In FIG. 4, P1 to P9 indicate the pressure values of the precharge pressure Pa, and the pressure values increase in the order of P1, P2, P3, .... Further, PL1 to PL4 indicate the pressure value of the line pressure PL, and the pressure value increases in the order of PL1, PL2, PL3 ... Further, there is a relationship of P6 = PL1, P7 = PL2, P9 = PL4.

Unless the precharge pressure Pa is set higher than the line pressure PL, the flow rate increases as the precharge pressure Pa increases, but it is presumed that the flow rate is constant with respect to the line pressure PL. However, as shown in FIG. 4, for example, when the precharge pressure Pa is P4 or P5, when the precharge pressure Pa is P6 when the line pressure PL is PL2 or more, or when the line pressure PL is PL3 or more, the precharge pressure is It was found that when Pa is P7 or P8, the flow rate decreases as the line pressure PL increases.

Considering this cause, when the line pressure PL is high and the precharge pressure Pa is low, as shown in FIG. 2B, the flow of hydraulic fluid flowing between the input port or output port and the inside of the spool chamber 51 ( It is presumed that the flow rate of the hydraulic oil is reduced by a hydrodynamic action such as (fluid force) acting on the spool 52 [FIG. 2 (b) illustrates the flow of the fluid with an arrow]. For example, in FIG. 2B, it is presumed that the flow rate of the hydraulic oil decreases when the spool 52 is pushed to the left in the drawing by the flow of the hydraulic oil and the opening of the input port is narrowed. It is also presumed that the large pressure difference from the line pressure increases the flow velocity of the oil, which causes a violent turbulence in the spool chamber and reduces the output flow rate.
As described above, when the flow rate of the hydraulic oil decreases, the backlash of the friction engaging element may not be completed due to precharging, so countermeasures are required.

Therefore, in this control device, the ATCU 6 has a differential pressure ΔP (= PL−) between the line pressure PL and the initially set precharge pressure indicated value (precharge pressure Pa indicated pressure) Pds during the backlash control. When Pds) is larger than the predetermined value P0, the precharge pressure indicated value Pd is increased and corrected. Further, the ATCU 6 sets the increase correction amount α at this time to be larger as the differential pressure ΔP is larger. Therefore, the larger the differential pressure ΔP, the higher the precharge pressure indicated value Pd will be corrected.

[Action and effect]
Since the control device for the stepped transmission according to the present embodiment is configured as described above, rattling control can be performed, for example, as shown in the flowchart of FIG. Since the target of this backlash packing control is the friction engagement element for establishing the shift stage, if a shift instruction is sent to the shift stage that requires a state change from the release of the friction engagement element to the engagement. Assuming that the start condition of the backlash packing control is satisfied for the friction engaging element to be engaged, the backlash filling control is started.

As shown in FIG. 5, first, it is determined whether or not to start the backlash filling control (whether the start condition of the backlash filling control is satisfied) (step S10), and if the backlash filling control is not started, the current control is performed. End the cycle processing. When starting the backlash filling control, the line pressure PL (indicated value or actual value) at that time and the precharge indicated value Pds preset in advance according to the friction engaging element to be controlled and the driving state of the vehicle. And are read (step S20).

Next, the differential pressure ΔP (= PL-Pds) between the line pressure PL and the initially set precharge indicated value Pds is calculated, and it is determined whether or not this differential pressure ΔP is larger than the predetermined value P0 (step). S30). If the differential pressure ΔP is not larger than the predetermined value P0, the initially set precharge instruction value Pds is used as it is as the precharge instruction value Pd (step S60), and precharge is performed (step S70).

On the other hand, when the differential pressure ΔP is larger than the predetermined value P0, the correction amount α corresponding to the differential pressure ΔP set for each friction engaging element is set (step S40), and the precharge pressure indicated value Pds is set to this. The precharge pressure indicated value Pd that has been upwardly corrected by adding the correction amount α is set (step S50). Then, precharging is performed using the precharge pressure indicated value Pd corrected for the increase (step S70).

In this way, when the differential pressure ΔP between the line pressure PL and the precharge pressure indicated value Pds is larger than the predetermined value P0, when the precharge pressure indicated value Pd is corrected for increase, the operation of precharging by the amount of the increase correction is performed. The flow rate of oil can be increased, and even when the precharge pressure Pas is significantly smaller than the line pressure PL, the shortage of the flow rate of the oil to be precharged in the oil chamber is suppressed, and the backlash is properly packed. be able to.

Further, the larger the differential pressure ΔP, the larger the shortage of the flow rate, but the increase correction amount α of the precharge pressure indicated value Pd is increased accordingly to correct the precharge pressure Pa to a higher oil pressure. It is possible to properly compensate for the shortage of the flow rate and to carry out the backlash filling more appropriately.

〔others〕
Although the embodiment has been described above, the present invention is not limited to such an embodiment, and the embodiment may be appropriately modified and implemented.
For example, in the above embodiment, when the differential pressure ΔP between the line pressure PL and the precharge pressure indicated value Pds is larger than the predetermined value P0, the larger the differential pressure ΔP, the larger the increase correction amount α and the precharge pressure instruction. Although the value Pd is corrected to a higher oil pressure value, a certain effect can be obtained even if the correction amount α is set uniformly.

Further, as shown in FIG. 4, since the flow rate reduction characteristics with respect to the differential pressure ΔP and the line pressure PL differ depending on the precharge pressure Pa, the precharge pressure indicated value Pd may be corrected for increase based on the flow rate reduction characteristics. good.

1 Engine (internal combustion engine) that is the drive source
2 Torque converter 3 Stepped automatic transmission mechanism 4 Power transmission system 5 Flood control unit 6 Automatic transmission control unit as a control means (hereinafter ATCU)
7 Oil pump 10 Stepped automatic transmission (stepped transmission)
31 Friction engagement element 50 Hydraulic control valve 51 Spool chamber 52 Spool 53 Return spring 54 Solenoid 70 Pressure regulating valve (pressure regulator valve)
PL line pressure Pa Precharge pressure Pd Precharge pressure indicated value Pds Initially set precharge pressure indicated value

Claims (4)

In a stepped transmission control device provided with a hydraulic control unit for supplying hydraulic pressure to an oil chamber of a friction engaging element for establishing a shift stage and a control means for controlling the hydraulic control unit.
The hydraulic control unit includes a regulator valve that generates a line pressure and a pressure adjusting valve that adjusts the hydraulic pressure supplied to the oil chamber of the friction engaging element using the line pressure as a source pressure.
The control means controls the pressure adjusting valve based on the precharge pressure indicated value with respect to the friction engagement element that switches from the released state to the engagement state, precharges the oil chamber, and causes the friction engagement. It is a control to reduce the backlash of the elements, and at the start of the control, the backlash filling control is performed in which the pressure is gradually increased to the precharge pressure for a predetermined time and then decreased to the predetermined pressure.
In the case of the backlash filling control, the control means sets the precharge pressure instruction value when the difference pressure between the line pressure and the preset precharge pressure instruction value is larger than a predetermined value. A stepped transmission control device characterized by upward correction. The control device for a stepped transmission according to claim 1, wherein the control means increases and corrects the precharge pressure indicated value higher as the differential pressure increases. The control device for a stepped transmission according to claim 1 or 2, wherein the control means increases and corrects the precharge pressure indicated value based on the flow rate decrease characteristic with respect to the differential pressure. The control device for a stepped transmission according to any one of claims 1 to 3, wherein the regulator valve can change the level of the line pressure.

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