JP5215932B2 - Control device for four-wheel drive vehicle transfer clutch - Google Patents

Description

  The present invention relates to a control device for a transfer clutch of a four-wheel drive vehicle in which a driving force from a driving source is transmitted to either a front wheel side or a rear wheel side via a propeller shaft, and a clutch torque is set by duty control.

  Conventionally, in a transfer clutch of a four-wheel drive vehicle in which a driving force from a driving source is transmitted to either the front wheel side or the rear wheel side via a propeller shaft and the clutch torque is set by duty control, The drive frequency is set near a specific frequency (for example, 50 Hz). By the way, the torsion of the drive system from the transfer clutch to the propeller shaft and the rear wheel via the rear differential device, and the natural frequency of the vehicle transmission system from the differential mount to the vehicle body via the cross member are also near the above-mentioned specific frequency. If the duty ratio with respect to the transfer clutch is within a predetermined range, the vibration of the drive system may cause vehicle body resonance and generate sound and vibration.

  Therefore, it is conceivable to change the drive frequency of the duty solenoid of the transfer clutch. For example, Japanese Patent Application Laid-Open No. Sho 62-215158 (hereinafter referred to as Patent Document 1) discloses a technique of a fluid pressure control device for an automatic transmission provided with a control frequency changing means for changing a drive frequency of a duty solenoid over time. ing. Further, in Japanese Patent Laid-Open No. 10-318360 (hereinafter, referred to as Patent Document 2), when the engine speed becomes around 6000 rpm corresponding to an integral multiple of a normal line pressure solenoid drive frequency (50 Hz), the resonance frequency is indicated. A technology of a duty solenoid control device that avoids resonance of the solenoid and instability of the line pressure by switching to other 35 Hz is disclosed.

JP-A-62-215158 JP 10-318360 A

  However, the method of switching the driving frequency as in the above-described prior art effectively copes with all of various operating conditions (engine operating state, outside air temperature, road surface state, etc.) and various structures of the power transmission system. There is a problem that it is difficult. In general, the drive frequency at which the duty solenoid can exhibit the required characteristics is determined to some extent. Therefore, if the drive frequency is switched as in the above-described prior art, the desired performance may not be realized. There is. Further, since the duty solenoid tends to be difficult to set on the side where the driving frequency is increased due to the responsiveness of the spool, the duty solenoid is usually changed to the side where the driving frequency is lowered (for example, the above-mentioned patents). In Reference 2, the frequency is switched from 50 Hz to 35 Hz), but there is a possibility that the output hydraulic pressure will fluctuate greatly.

  The present invention has been made in view of the above circumstances, and it effectively suppresses the resonance of the vehicle body with respect to various driving conditions and the structure of the power transmission system, thereby reliably preventing the generation of sound and vibration, and the duty. An object of the present invention is to provide a stable and reliable control device for a transfer clutch of a four-wheel drive vehicle, in which a solenoid can exhibit its performance appropriately and does not cause a large fluctuation in the output hydraulic pressure. .

  The present invention provides a control device for a transfer clutch of a four-wheel drive vehicle that transmits a driving force from a drive source to either the front wheel side or the rear wheel side via a propeller shaft. Clutch torque setting means for setting to, a duty solenoid valve disposed in a hydraulic drive system for driving the transfer clutch, and an ON time and OFF within one cycle of a preset drive cycle for driving the duty solenoid valve Duty ratio setting means for setting the clutch torque with the duty ratio of time, and the start timing of either the ON time or the OFF time set by the duty ratio setting means is randomly variable for each period in the driving period. And a start timing varying means.

  According to the control device for a transfer clutch of a four-wheel drive vehicle according to the present invention, the resonance of the vehicle body is effectively suppressed even for various driving conditions and the structure of the power transmission system, thereby reliably preventing the generation of noise and vibration. In addition, the duty solenoid can exhibit its performance appropriately, and there is an excellent effect that the stability and reliability are high without causing a large fluctuation in the output hydraulic pressure.

1 is a skeleton diagram showing an outline of a drive system of a four-wheel drive vehicle according to an embodiment of the present invention. It is a schematic explanatory drawing of the transfer clutch and duty solenoid which concern on one Embodiment of this invention. It is a flowchart of the duty control program with respect to the duty solenoid which concerns on one Embodiment of this invention. It is explanatory drawing of the duty ratio map which concerns on one Embodiment of this invention. It is a time chart which shows an example of the output signal with respect to the duty solenoid which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, a drive system of a four-wheel drive vehicle to which the present invention is applied will be described with reference to FIG.

  In the figure, reference numeral 1 denotes an automatic transmission, and a transmission case 4 is joined to the rear part of the torque converter case 2 and the differential case 3, and an extension case 5 is joined to the rear part of the transmission case 4. An oil pan 6 for storing automatic transmission oil is attached to the lower part of the transmission case 3.

  A torque converter 8 having a lock-up clutch 7 is arranged inside the torque converter case 2, and an input element (impeller) of the torque converter 8 is connected to a crankshaft 9 a of the engine 9. An automatic transmission mechanism 10 is disposed inside the transmission case 4, and a transmission input shaft 11 of the automatic transmission mechanism 10 is connected to an output element (turbine) of the torque converter 8. The input shaft 11 and the transmission output shaft 12 of the automatic transmission mechanism 10 are coaxially disposed, and the transmission output shaft 12 is connected to a transfer device 13 disposed in the extension case 5.

  The automatic transmission mechanism 10 has a configuration in which two sets of front planetary gears 14 and rear planetary gears 15 obtain four forward speeds, one reverse speed, a high clutch 16, a reverse clutch 17, a multi-plate brake 18, a low clutch 19, An and reverse brake 20 and a one-way clutch 21 are arranged in parallel, and selectively engaged with each other to obtain four forward speeds and one reverse speed.

  In the transmission case 4, a front drive shaft 22 is disposed in parallel with the input shaft 11 and the output shaft 12, and the front end side of the front drive shaft 22 is connected to a front differential device 23 disposed in the differential case 3. To transmit the driving force to the front wheels. The rear end side of the front drive shaft 22 is connected to the transmission output shaft 12 via a pair of reduction drive gears 24 and a reduction driven gear 25.

  A rear drive shaft 26 is rotatably inserted into the rear end of the transmission output shaft 12, and a transfer device 13 is formed between the transmission output shaft 12 and the rear drive shaft 26. Driving force is transmitted to the rear wheels via the propeller shaft 27, the rear differential device 28, and the like.

  On the other hand, an oil pump housing 29a is sandwiched between the torque converter case 2 and the transmission case 4 on the front side of the automatic transmission mechanism 10, and the automatic transmission oil stored in the oil pan 6 is supplied to each part. An oil pump 29 is provided for pressure feeding.

  The drive shaft 30 of the oil pump 29 and the impeller sleeve 8a of the torque converter 8 are connected, and the oil pump 29 is directly connected to the engine 9 and is always driven during engine operation.

  The transmission input shaft 10 is rotated coaxially with the crankshaft 9a of the engine 9 via a bearing (not shown) by a hollow support 29c formed at the center of the oil pump cover 29b covering the oil pump housing 29a. It is supported freely.

  The automatic transmission oil pumped by the oil pump 29 is, as is well known, optimal line pressure and pilot pressure depending on the operating condition by the pressure regulator valve, pilot valve, etc. in the control valve unit 31 housed in the oil pan 6. And is supplied as hydraulic oil for the torque converter 8, valves, clutches, brakes, gears, and the like, and lubricating oil for each part.

  Further, as shown in FIG. 2, the transfer device 13 controls the hydraulic unit 50 by a transmission control unit (TCU) 60 constituted by a microcomputer or the like, and operates according to the hydraulic pressure of the automatic transmission oil from the hydraulic unit 50. A transfer clutch 40 composed of a wet hydraulic multi-plate clutch is arranged between the transmission output shaft 12 and the rear drive shaft 26.

  The transfer clutch 40 has a clutch hub 41 fixed to the transmission output shaft 12, a clutch drum 42 fixed to the rear drive shaft 26, a plurality of drive plates 43 from the clutch hub 41, and a plurality of driven from the clutch drum 42. The plate 44 is configured by alternately stacking the plates 43 and 44, respectively.

  Also, pistons 46 that press the plurality of plates 43, 44 by the hydraulic pressure of the automatic transmission oil supplied to the hydraulic chamber 45 are stored in portions of the clutch drum 42 facing the plates 43, 44.

  Here, the driving force from the transmission output shaft 12 is distributed by the transfer device 13 and transmitted to the front wheels via the reduction drive gear 24, the reduction driven gear 25, and the front drive shaft 22, while the clutch hub 41, the drive plate 43, the driven plate 44, the clutch drum 42, and the rear drive shaft 26, power is transmitted to the rear wheels. Therefore, by making the fastening force of the transfer clutch 40 variable by the hydraulic pressure of the ATF supplied to the hydraulic chamber 45, the power distribution amount for the front and rear wheels can be set between front wheel: rear wheel = 100: 0-50: 50. It can be set to be variable.

  On the other hand, in the hydraulic unit 50, a duty solenoid valve 52 that is duty-controlled according to the duty ratio of the duty signal output from the TCU 60 is connected to the transfer control valve 51 disposed on the side surface of the extension case 5 via the oil passage 53. And communicated.

  In the transfer control valve 51, the spool 51b is activated by the transfer duty pressure from the duty solenoid valve 52 acting on the land 51a via the oil passage 53, and is supplied via the oil passage 54. By adjusting the drain amount of the automatic transmission oil from 31 by the operation of the spool 51 b, the line pressure is adjusted to the transfer clutch pressure and supplied to the hydraulic chamber 45 of the transfer clutch 40 through the oil passage 55.

  That is, as is well known, a pressure pressure modifier solenoid valve (not shown) for operating a pressure modifier valve built in the control valve unit 31 is controlled by the TCU 60 in accordance with the operating state. A pressure modifier pressure (signal pressure) is applied to the pressure regulator valve by the valve, and the hydraulic pressure from the oil pump 29 is adjusted by the operation of the pressure regulator valve to obtain an appropriate line pressure according to the operating state. Further, the line pressure is adjusted to a constant pilot pressure by a pilot valve (not shown), and the pilot pressure is guided to the duty solenoid valve 52.

  The duty solenoid valve 52 is operated to open by the exciting force of the solenoid 52a generated corresponding to the duty ratio of the duty signal output from the TCU 60 to the solenoid 52a, thereby adjusting the drain amount. Is adjusted to the transfer duty pressure, and the transfer duty pressure is applied to the land 51 a of the transfer control valve 51 through the oil passage 53. In the transfer control valve 51, the spool 51b is operated according to the transfer duty pressure acting on the land 51a, and the operation of the spool 51b adjusts the line pressure supplied from the oil passage 54 to the transfer clutch pressure. The oil is supplied to the hydraulic chamber 45 of the transfer clutch 40 through the oil passage 55.

  The transfer clutch 40 is differentially limited by the transfer clutch pressure acting on the hydraulic chamber 45 to control the power distribution amount between the front and rear wheels.

  In this embodiment, for example, 20 ms is set as a unit time (one cycle) (with a driving frequency of 50 Hz), and the duty ratio of the duty signal is determined by the ratio of the ON time to the unit time.

  As the duty ratio increases, the drain amount of the automatic transmission oil by the duty solenoid valve 52 decreases, and accordingly, the transfer duty pressure acting on the land 51a of the transfer control valve 51 increases, and the transfer control valve 51 increases. As a result, the transfer clutch pressure that is regulated by the transfer control valve 51 and acts on the hydraulic chamber 45 of the transfer clutch 40 increases, thereby increasing the engagement force of the transfer clutch 40 and increasing the rear wheel side. Increased power distribution to Conversely, as the duty ratio decreases, the drain amount of the automatic transmission oil by the duty solenoid valve 52 increases, the transfer duty pressure acting on the land 51 a of the transfer control valve 51 decreases, and the transfer control valve 51. As the drain amount increases, the transfer clutch pressure acting on the hydraulic chamber 45 of the transfer clutch 40 decreases, and accordingly, the fastening force of the transfer clutch 40 decreases and the power distribution amount to the rear wheel side is reduced. Decrease.

  On the other hand, the transmission control unit (TCU) 60 is composed of peripheral circuits such as a microcomputer and a drive circuit. The transmission control unit (TCU) 60 is a vehicle speed sensor for detecting the rear wheel output shaft rotational speed as a vehicle speed, and an engine 9 throttle valve (not shown) is opened. A throttle opening sensor that detects the degree, a range switch that detects a select position (P, R, N, D, 3, 2, and 1 range positions) by a shift lever as a shift position, and a brake pedal that detects a brake operation A brake switch that is turned on and off in response to the depression and release of the engine, an automatic transmission oil temperature sensor that detects the oil temperature of the automatic transmission oil, and sensors such as a steering angle sensor (not shown) and switches 61 are connected. .

  The TCU 60 determines the operating state based on signals input from these sensors and switches, and controls each solenoid valve and duty solenoid valve (not shown) for operating each control valve built in the control valve unit 31. The control amount is calculated according to the operating state, and a drive signal corresponding to the control amount is output to each solenoid valve and duty solenoid valve to perform shift control.

  Further, the TCU 60 calculates the duty ratio of the duty signal for the duty solenoid valve 52 appropriate for obtaining the power distribution amount between the front and rear wheels according to the driving state, and outputs the duty signal of this duty ratio to the duty solenoid valve 52. To do. Then, the transfer duty pressure is adjusted by the duty solenoid valve 52, the transfer control valve 51 is operated in accordance with the transfer duty pressure, the line pressure supplied from the oil passage 54 is adjusted to the transfer clutch pressure, and the transfer clutch 40 The hydraulic chamber 45 is supplied. As described above, the TCU 60 differentially restricts the transfer clutch 40 according to the driving state, and controls the power distribution amount between the front and rear wheels.

  Here, in the power distribution control, the TCU 60 sets the duty ratio LSD_duty of the duty signal for the duty solenoid valve 52 for operating the transfer clutch 40 constituting the transfer device 13 to variably control the driving force distribution amount between the front and rear wheels. For example, the vehicle speed and the throttle opening are set as parameters using a map (see FIG. 4).

  The duty ratio LSD_duty of the duty signal for the duty solenoid valve 52 set in this way is output to the duty solenoid valve 52 in accordance with a duty control program for the duty solenoid described later.

  Specifically, the TCU 60 uses this duty control program to turn on the duty ratio within one cycle of 20 ms of the above-described drive cycle (drive frequency of 50 Hz in the present embodiment) for driving the duty solenoid valve 52. The start timing is randomly varied for each cycle in the drive cycle. Here, the random change of the start timing is executed when the duty ratio is a predetermined value C (for example, 30%) or less. As described above, the TCU 60 is configured to have functions as clutch torque setting means, duty ratio setting means, and start timing variable means.

Next, the above-described duty control program will be described with reference to the flowchart of FIG.
First, in step (hereinafter abbreviated as “S”) 101, the count value Cnt of the main counter is read. In the present embodiment, this main counter is a counter that counts 100 per cycle (20 ms) of the above-described 50 Hz driving cycle.

  Next, it progresses to S102 and reads duty ratio LSD_duty which TCU60 set according to the driving | running state.

  Then, the process proceeds to S103, where the duty ratio LSD_duty is compared with a predetermined value C (for example, 30%). If the duty ratio LSD_duty is equal to or less than the predetermined value C, the process proceeds to S104, and the ON time start timing t_delay is randomly set. Set and proceed to S106.

  The random setting of the start timing t_delay in S104 is set according to, for example, a random number corresponding to the preset count value Cnt of the main counter and the duty ratio LSD_duty set by the TCU 60 according to the operating state. The

The random number corresponding to the count value Cnt of the main counter set in advance is, for example, the random number N_R in the reference duty ratio D_B, and is, for example, 0 as the duty ratio based on the duty ratio of 30%. To (100-30) are set in advance, and are set in order such as “0, 32, 51, 28, 69...”. When the currently read random number is N_Rn with respect to the currently set duty ratio LSD_dutyn, the current start timing t_delayn is set by the following equation (1).
t_delayn = (100−LSD_dutyn) · N_Rn / (100−D_B) (1)
The random setting of the start timing t_delay described above may be set by other methods such as a setting by applying a predetermined random function, a setting by a map for each duty ratio, and the like.

  If the duty ratio LSD_duty exceeds the predetermined value C as a result of the comparison in S103, the process proceeds to S105, where the ON time start timing t_delay is started without delay, that is, from the beginning of one vibration cycle. The process proceeds to S106. That is, when the duty ratio LSD_duty exceeds the predetermined value C, the duty ratio is increased, the pulsation in the hydraulic circuit is reduced, and the influence of resonance with the vehicle body transmission system is reduced. The timing t_delay is not varied randomly.

  When the start timing t_delay is set in S104 or S105 and the process proceeds to S106, the count value Cnt of the main counter is equal to or less than the start timing t_delay (Cnt ≦ t_delay), or the count value Cnt of the main counter is greater than (t_delay + LSD_duty) ( It is determined whether or not Cnt> (t_delay + LSD_duty). If this condition is not satisfied, that is, if t_delay <Cnt ≦ (t_delay + LSD_duty), the routine proceeds to S107 where the duty solenoid valve 52 is turned on and the routine is exited. On the other hand, if Cnt ≦ t_delay or Cnt> (t_delay + LSD_duty), the routine proceeds to S108, where the duty solenoid valve 52 is turned OFF and the routine is exited.

  Next, an example of an output signal for the duty solenoid will be described with reference to a time chart of FIG. 5 (a) and 5 (b) both show an output signal with a driving frequency of 50 Hz and a duty ratio of 30%, FIG. 5 (a) shows a conventional output signal with a constant delay time of 0, FIG. 5B shows the embodiment in which the delay time is variably set randomly for each period in the drive period.

  In the conventional output signal of FIG. 5A, the drive system twists from the transfer clutch 40 to the rear wheel via the propeller shaft 27 and the rear differential device 28, or the vehicle body transmission from the differential mount to the vehicle body via the cross member. There is a possibility that the natural frequency of the system and the drive frequency of the duty solenoid resonate to generate sound and vibration.

  However, in the case of the present embodiment in FIG. 5B, the driving frequency for the duty solenoid is constant at 50 Hz, but apparently 38.5 Hz (period 26 ms), 58.8 (period 17 ms), 35.7 Hz. (Period 28 ms), and so on, the resonance of the natural frequency of the vehicle body transmission system and the like and the drive frequency of the duty solenoid is effectively suppressed, and the generation of sound and vibration is ensured. It is to be prevented.

  In FIG. 5 (b), the start time of the ON time in each cycle is indicated by time (0 → 6ms → 3ms → 11ms →...), But the value of the above start timing t_delay. Then, (0 → 30 → 15 → 55 →...)

  As described above, according to this embodiment, the start timing of the ON time, which is the duty ratio within one cycle of the drive cycle for driving the duty solenoid valve 52, is randomly varied for each cycle in the drive cycle. Therefore, regardless of the specific driving conditions and structure, it is possible to effectively prevent the generation of noise and vibration by effectively suppressing the resonance of the vehicle body for various driving conditions and the structure of the power transmission system. Is possible. In addition, since the drive cycle for driving the duty solenoid valve 52 is realized without changing, the duty solenoid can appropriately exhibit its performance, and the output hydraulic pressure may fluctuate greatly. It has an excellent effect of high stability and reliability.

  In the present embodiment, the start timing of the ON time is randomly varied for each cycle in the drive cycle, but the start timing of the OFF time is varied randomly for each cycle in the drive cycle. Anyway.

1 automatic transmission 9 engine 13 transfer device 26 rear drive shaft 27 propeller shaft 28 rear differential device 31 control valve unit 40 transfer clutch 46 piston 50 hydraulic unit 51 transfer control valve 52 duty solenoid valve 52a solenoid 60 transmission control device (clutch torque setting) Means, duty ratio setting means, start timing variable means)
61 Sensors and switches

Claims (2)

In a control device for a transfer clutch of a four-wheel drive vehicle that transmits a driving force from a driving source to either the front wheel side or the rear wheel side via a propeller shaft,
Clutch torque setting means for setting a predetermined clutch torque for fastening the transfer clutch;
A duty solenoid valve disposed in a hydraulic drive system for driving the transfer clutch;
A duty ratio setting means for setting the clutch torque at a duty ratio of an ON time and an OFF time within a preset driving cycle for driving the duty solenoid valve;
Start timing variable means for randomly changing the start timing of either the ON time or the OFF time set by the duty ratio setting means for each period in the drive period;
A control device for a transfer clutch of a four-wheel drive vehicle.   2. The four-wheel drive vehicle according to claim 1, wherein the start timing variable means changes the start timing when the duty ratio set by the duty ratio setting means is equal to or less than a preset duty ratio. Transfer clutch control device.

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