JP3112992B2 - Vehicle power transmission control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission control device for a vehicle having a differential device provided with an electromagnetic clutch type differential limiting mechanism.

[0002]

2. Description of the Related Art An output from a transmission is transmitted to a front wheel drive system and a rear wheel drive system via a center differential device (hereinafter referred to as a "center differential"), and the front wheel drive system and the rear wheel drive system are selectively used. In a four-wheel drive vehicle provided with a clutch for limiting the differential in the center differential to directly connect to the center differential, the clutch is actuated at extremely low speeds including when the vehicle is stopped to lock the center differential so that the center differential can be locked at start-up and A differential limiting control device capable of obtaining sufficient traveling performance during acceleration is known (Japanese Utility Model Application Laid-Open No. 61-2).
01939).

[0003]

When the differential limiting clutch is an electromagnetic clutch, the differential limiting amount is substantially proportional to the supplied current until the clutch is saturated. Therefore, if the center differential is locked when the vehicle does not actually need to be locked, power consumption increases, which increases the load on the alternator, and thus increases the load on the engine, thus deteriorating fuel efficiency.

[0004] Therefore, the present invention relates to a vehicle equipped with a differential device provided with an electromagnetic clutch type differential limiting mechanism and operating means capable of selecting a differential limiting amount of the differential limiting mechanism, which is used when the vehicle stops. It is an object of the present invention to provide a power transmission control device that reduces fuel consumption and improves fuel efficiency.

[0005]

According to a first aspect of the present invention, a current is supplied to the differential limiting mechanism after a lapse of a predetermined time from a point in time when the vehicle speed is zero and the shift position of the transmission is in a neutral state. The object is to solve the above-mentioned problem by providing a blocking means.

[0006]

According to the first aspect of the present invention, when the vehicle is stopped for a short time with the intention to immediately start by interrupting the current supply to the electromagnetic clutch only when there is no intention to start, Since the current supply is continued, unnecessary switching operation can be eliminated.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the four-wheel drive vehicle has a power train P including an engine 1, a transmission 2, and a transfer device 4 including a center differential 3 having an electromagnetic clutch type differential limiting mechanism (EMCD). The torque inputted to the center differential 3 is distributed to the front wheel side propeller shaft 5 and the rear wheel side propeller shaft 6 and outputted.

The torque of the front wheel side propeller shaft 5 is input to a front differential 7 having an electromagnetic clutch type differential limiting mechanism (EMCD), and further transmitted to a left front wheel 9 via a left front axle shaft 8. The power is transmitted to the right front wheel 11 via the right front axle shaft 10. On the other hand, the torque of the rear wheel side propeller shaft 6 is controlled by an electromagnetic clutch type differential limiting mechanism (EMC).
D), and is transmitted to the left rear wheel 14 via the left rear axle shaft 13 and to the right rear wheel 16 via the right rear axle shaft 15. Center differential 3,
The electromagnetic clutch type differential limiting mechanism (EMCD) provided in each of the front differential 7 and the rear differential 12 is configured such that each differential limiting amount is controlled by a current output from the differential limiting amount controller 20. .

The differential limit controller 20 is a digital controller constituted by a microcomputer, and is detected by a throttle sensor 21 provided for a throttle valve (not shown) in an intake passage of the engine 1. Throttle opening signal TVO, a brake switch 22 provided for a brake pedal (not shown).
ON / OFF signal generated by transmission, transmission 2
, A neutral signal output from a neutral switch 23 provided in the controller, an ABS operation signal output from an ABS controller 24 for controlling an antilock brake system (ABS), and the like are input to the differential limit controller 20.

Further, the left front axle shaft 8
, The front left wheel speed (rotation speed) NfL detected by the first rotation speed sensor 25 provided to the right front wheel speed (rotation speed) detected by the second rotation speed sensor 26 provided to the right front axle shaft 10. Rotation speed) NfR,
A third provided for the left rear axle shaft 13
The left rear wheel speed (rotation speed) NrR detected by the rotation speed sensor 27 and the right rear wheel speed (rotation speed) NrR detected by the fourth rotation speed sensor 28 provided for the right rear axle shaft 15 are respectively represented. Signal is AB
Differential limit controller 2 via S controller 24
0 is input. The differential limiting amount controller 20 uses these signals as input information in a manner to be described later, by using the center differential 3, the front differential 7, and the rear differential 12
Each of the differential limiting mechanisms is controlled by a current to improve the running stability, fuel efficiency, and the like of the four-wheel drive vehicle. The differential limit controller 20 is provided with an operation knob 29 capable of selecting four control modes of an auto mode Auto, a center differential lock mode C, a rear differential lock mode R, and a front differential lock mode F.

Hereinafter, a control method of the differential limiting force control by the differential limiting amount controller 20 will be described with reference to the flowchart of FIG.

FIG. 2 shows a routine for calculating the vehicle speed Vsp. In step S1, four wheel speeds (rotations) Nf are set.
L, NfR, NrL, and NrR are input. Then, in step S2, the minimum value of the four wheel speeds is defined as the vehicle speed Vsp.

FIG. 3 shows a routine for calculating a center differential differential rotation speed (rotational speed difference between front and rear wheels) ΔNc. In step S3, four wheel speeds NfL, NfR, NrL, Nr are determined.
R is input, and in step S4, the center differential rotation speed Δ
Nc is calculated by the following equation.

ΔNc = | (NfL + NfR) / 2− (N
rL + NrR) / 2 | FIG. 4 shows a rear differential differential speed (rotational speed difference between left and right rear wheels) Δ
This shows a calculation routine for Nr. In step S5, the rear wheel speeds NrL and NrR are input, and in the next step S26, the rear differential differential rotation speed ΔNr is calculated by the following equation.

ΔNr = | NrL−NrR | FIG. 5 shows a map control current value setting routine of the center differential 3. First, at step S7, the control current value I of the center differential 3
c is set as a function of the center differential rotation speed ΔNc and the throttle opening TVO. Next, in step S8, the control current value Ic is set to the maximum current value Imax (lock current value, Imax =
2.2 amps) or more, and if this determination is "YES", the timer Tc is reset in a step S9, and in the next step S10, the map control current value Ica =
Set to Imax. In step S11, the timer is incremented. In step S12, it is determined whether or not the timer time has become equal to or longer than a predetermined hold time Ta.
While it is Ta, the process returns to step S11 to increment the timer time. Then, the determination in step S12 is “Y
When "ES" is reached, the process returns to step S7. FIG. 10 is a map showing the relationship between the control current value Ica and the center differential rotation speed ΔNc.

FIG. 6 shows a map control current value setting routine for the rear differential 12. As in the case of FIG. 5, first, in step S13, the control current value Ir of the rear differential 12 is set as a function of the rear differential differential rotation speed ΔNr and the throttle opening TVO. Next, in step S14, it is determined whether or not the control current value Ir is greater than or equal to a maximum current value Imax (lock current value, Imax = 4.1 amps), and this determination is "YES".
If so, the timer Tr is reset in step S15,
In the next step S16, the map control current value Ira = Imax is set. Then, in step S17, the timer is incremented. In step S18, it is determined whether or not the timer time has exceeded a predetermined hold time Ta, and Tr <Ta
If so, the process returns to step S17 to increment the timer. When the determination in step S18 becomes "YES", the process returns to step S13. A map showing the relationship between the control current value Ira and the rear differential rotation speed ΔNr is shown in FIG.

FIGS. 7 to 9 are flowcharts of a control current value determination routine for the front differential 7, the center differential 3, and the rear differential 12. First, in step S19, the map control current values Ica, Ira, AB set in FIG. 5 and FIG.
The S signal, the brake signal, the control mode signal, and the vehicle speed Vsp calculated in FIG. 2 are input. And step S
At 20, it is determined whether the control mode is the auto mode. If the mode is the auto mode, the process proceeds to step S21, where it is determined whether or not the brake switch 22 is ON. If the mode is braking, If = 0, Ic in step S22.
= 0 and Ir = 0. If braking is not being performed, in step S23, the control current value If of the front differential is set to 0, and the control current values Ic of the center differential 3 and the rear differential 7,
Ir is the map control current values Ica and Ira set in FIGS. 5 and 6, respectively.

If the determination in step S20 is "NO", it is determined in next step S24 whether the control mode is the center lock mode. If the mode is the center lock mode, a center differential lock mode control routine shown in FIG. 8 is executed. The determination in step S24 is “N
If "O", the process proceeds to step S25, and it is determined whether the control mode is the rear differential lock mode. If the control mode is the rear lock mode, a rear lock mode control routine shown in FIG. 9 is executed. If the determination in step S25 is also "NO", the operation is in the front lock mode, and therefore, step S2
Then, the control current value is determined according to the vehicle speed Vsp.

In steps S26, S27 and S28, the vehicle speed Vsp is 100 km / h or more, less than 100 km / h, 50 km / h or more, less than 50 km / h, 30 km / h or more, or 30 km / h. It is respectively determined whether the number is less than or equal to. When the vehicle speed Vsp is 100 km / h, the control current value If of the front differential is set to 0 in step S29, and the control current values Ic and Ic of the center differential 3 and the rear differential 7 are set.
Ir is the map control current values Ica and Ira set in FIGS. 5 and 6, respectively. The vehicle speed Vsp is 100km /
If it is less than 50 km / h or less than h, in step S30, I
Let f = 0, Ic = 2.2 amps (Imax), and Ir = Ira. If the vehicle speed Vsp is less than 50 km / h and greater than 30 km / h, then in step S31, If = 0, Ic = 2.2 amps (Imax), and Ir = 4.1 amps (Imax).
Further, when the vehicle speed Vsp is 30 km / h or less, I
f = 2.1 amps (Imax), Ic = 2.2 amps (Ima
x) Lock all differentials as Ir = 4.1 amps (Imax).

In the center differential lock mode shown in FIG. 8, it is first determined in step S33 whether or not the brake switch 22 is ON. If the vehicle is not braking, it is determined in step S34 whether or not the vehicle speed Vsp is 100 km / h or more. Is determined. If it is 100 km / h or more, it is set to If = 0, Ic = Ica, and Ir = Ira in step S35. Also 10
If less than 0 km / h, If = 0, Ic = 2.2 amps
(Imax), Ir = Ira.

On the other hand, if the brake switch 22 is on, the flow advances to step S37 to determine whether or not the ABS has been activated. If the ABS has not been activated, the flow proceeds to step S3.
8, If = 0, Ic = 0.8 amps, and Ir = 0. When the ABS is operating, If = 0, Ic = 0, and Ir = 0 in step S39 so as not to hinder the ABS control.

Next, in the rear differential lock mode of FIG. 9, it is first determined in step S40 whether or not the brake switch 22 is on.
In S42, whether the vehicle speed Vsp is 100 km / h or more,
Less than 00km / h, 50km / h or more, or 50km
/ H is determined. If the vehicle speed Vsp is 100 km / h or more, If = 0 in step S43,
It is assumed that Ic = Ica and Ir = Ira. If the vehicle body speed Vsp is less than 100 km / h and greater than 50 km / h, step S44 is executed.
Where If = 0, Ic = 2.2 amps (Imax), Ir = Ira
It is said. Further, if the vehicle speed Vsp is less than 50 km / h, If = 0 and Ic = 2.2 amps (Im
ax), Ir = 4.1 amps (Imax), and the center differential 3 and the rear differential 12 are locked.

On the other hand, if the brake switch 22 is on, the flow advances to step S46 to determine whether or not the ABS has been activated. If the ABS has not been activated, the flow proceeds to step S4.
7, If = 0, Ic = 0.8 amps, and Ir = 1.2 amps. At the time of the operation of the ABS, in step S48, If = 0, Ic = 0,
Ir = 0 is set.

FIG. 10 is a diagram showing the relationship between the center differential differential rotation speed (= | front wheel rotation speed-rear wheel rotation speed |) ΔNc and the map control current value Ica of the center differential 3. In a region where α is equal to or less than Ica = 0, a front-wheel high-rotation-side dead zone is provided, and in a region where the center differential rotation speed ΔNc is between α and A,
Ica increases linearly with the increase of Nc, and the upper limit value Ima
to reach x. When Ica reaches Imax (2.2 amps), the center differential 3 is locked,
The differential between the front and rear wheels is completely stopped.

FIG. 11 is a diagram showing the relationship between the rear differential differential rotation speed (difference in rotation speed between the left and right rear wheels) ΔNr and the map control current value Ira of the rear differential 12, where the rear differential differential rotation speed ΔNr is β In the following region, Ira = 0 is set to provide a dead zone, and in the region where the rear differential differential rotation speed ΔNr is between β and B, Ira = 0 with respect to an increase in ΔNr.
Increases linearly to reach an upper limit value Imax (4.1 amps). When Ira reaches Imax, the differential between the left and right rear wheels is completely stopped.

The characteristic operation of the vehicle power transmission control device according to the present invention when the vehicle is stopped is shown in the flowchart of FIG. 12 and the timing chart of FIG.

In the flowchart of FIG. 12, first, in step S51, the vehicle speed Vsp calculated according to the flowchart of FIG. 2 and the neutral signal output from the neutral switch 23 provided in the transmission 2 in FIG. 1 are input. .

In the next step S52, it is checked whether or not the condition that Vsp = 0 and the condition that the shift position of the transmission 2 is neutral are satisfied at the same time. When this determination is "YES", That is, the time t in FIG.
In step S53, it is checked in step S53 whether a flag F for setting If, Ic, and Ir to zero is set. Since the determination in step S53 is "NO", the flow proceeds to step S54 to set the flag F, and at the same time, to step S5
At 5, the timer T for measuring, for example, 5 seconds is reset to start measuring time. In the next step S56, it is checked whether or not the timer T has timed out. Until the time is up, the control current values If, Ic, Ir of the front differential 7, the center differential 3, and the rear differential 12 are determined in step S57 in FIG.
To the current value according to the flow of FIG.

When step S53 is reached again through steps S51 and S52, the determination in step S53 is "YE
S ”, the timer T is incremented in step S58, and the process proceeds to step S56. At time t2 after 5 seconds from time t1 in FIG.
O ”, the process proceeds to step S59, If = 0, I
It is assumed that c = 0 and Ir = 0.

Next, when the transmission 2 is shifted to a position other than the neutral position at time t3 in FIG. 13 in order to start the vehicle in this stopped state, the determination in step S52 becomes "NO". Then, the flag F is defeated, and If, Ic,
Ir is returned to a current value according to the flow charts of FIGS.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a power transmission system of a four-wheel drive vehicle including a power transmission control device according to the present invention.

FIG. 2 is a flowchart of a vehicle speed calculation routine.

FIG. 3 is a flowchart of a routine for calculating a center differential differential rotation speed;

FIG. 4 is a flowchart of a rear differential differential speed calculation routine;

FIG. 5 is a flowchart of a center differential map control current value setting routine.

FIG. 6 is a flowchart of a rear differential map control current value setting routine.

FIG. 7 is a flowchart of a control current value determination routine.

FIG. 8 is a flowchart of a control current value determination routine connected to FIG. 7;

FIG. 9 is a flowchart of a control current value determination routine connected to FIG. 7;

FIG. 10 is a diagram showing a relationship between a center differential differential rotation speed and a center differential map control current value.

FIG. 11 is a diagram illustrating a relationship between a rear differential differential rotation speed and a map control current value of the rear differential.

FIG. 12 is a flowchart of a control current value determination routine when the vehicle stops.

FIG. 13 is a timing chart showing changes in a control current value with respect to a vehicle speed and a shift position of a transmission when the vehicle is stopped.

[Explanation of symbols]

 Reference Signs List 1 engine 2 transmission 3 center differential 4 transfer device 7 front differential 9 left front wheel 11 right front wheel 12 rear differential 14 left rear wheel 16 right rear wheel 20 differential limit controller 21 throttle sensor 22 brake switch 23 neutral switch 24 ABS controller 25-28 Speed sensor

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60K 17 / 35,23 / 04 F16H 48/30

Claims (2)

(57) [Claims] 1. A differential device having an electromagnetic clutch type differential limiting mechanism in which a differential limiting amount is varied according to a value of a supplied current, and a differential limiting amount of the differential limiting mechanism can be selected. A power transmission control device for a vehicle, comprising: an operating unit; and a means for interrupting a current supply to the differential limiting mechanism after a lapse of a predetermined time from a point in time when the vehicle speed becomes zero and the shift position of the transmission becomes neutral. A power transmission control device for a vehicle, comprising: 2. A blocked condition of the current supply device of claim 1, wherein a is released with the shift operation of the transmission.