Control device for four-wheel drive vehicles

Abstract

To provide a control device for a four-wheel drive vehicle which can stably control operation of a transmission and a hydraulic clutch in start of a driving power source.SOLUTION: A control device 100 has a travel state grasp part 102 for grasping a travel state of a vehicle 10, and a first clutch control part 104 for controlling the magnitude of an engaging degree of a first clutch transmitted through a clutch 46 for front wheel driving. The control device 100 performs control in start for prioritizing supply of oil to a transmission 20 over supply of oil to a clutch 46 for front wheel driving composed of a hydraulic clutch, until it satisfies such a condition that an oil discharge amount V in an oil pump 150 reaches a predetermined reference amount VS, under such a condition that a driving power source 12 starts output.SELECTED DRAWING: Figure 1

Description

Technical Field

[0004] ,

[0001] The present invention relates to a control device for a four-wheel drive vehicle.

Background Art

[0002] Conventionally, a control system and the like in an all-wheel drive vehicle disclosed in Patent Document 1 below have been provided as a control device for a four-wheel drive vehicle. The control system of Patent Document 1 below includes a first axle that is intermittently driven by a prime mover, a second axle that is constantly connected to the prime mover via a propeller shaft, and a sub-shaft that drivably connects the propeller shaft and the first axle. In an all-wheel drive vehicle, it controls the connection between the prime mover and the first axle. This control system includes a first clutch that connectably disconnects the propeller shaft and the sub-shaft, a second clutch that connectably disconnects the sub-shaft and the first axle, synchronization determination means for determining whether the second clutch can be connected, and connection determination means for determining whether the second clutch is connected. By adopting such a configuration, the control system of Patent Document 1 attempts to be able to quickly switch between the 2WD mode and the AWD mode while preventing the transmitted torque from having impactful or vibrational fluctuations.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, the inventors investigated the problems that might arise when, in a four-wheel drive vehicle with the configuration described above as the prior art, at least one of the first clutch and the second clutch is a hydraulically operated clutch. As a result, they found that in a four-wheel drive vehicle with a configuration that includes, in addition to a hydraulic clutch, an oil pump that operates using power output from an engine or the like which is a driving force source, and a transmission that operates using oil supplied by the oil pump, if the oil pump pressurized to operate both the transmission and the hydraulic clutch at the timing when the driving force source starts, there is a possibility that the operation control of the transmission and the hydraulic clutch may not be stable due to insufficient oil supply.

[0005] Therefore, the present invention aims to provide a control device for a four-wheel drive vehicle that can stably control the operation of the transmission and hydraulic clutch when the power source is started. [Means for solving the problem]

[0006] Through diligent research, the inventors have discovered that prioritizing the supply of oil to the transmission over the supply of oil to the hydraulic clutch during the startup of the power source allows for stable control of the operation of the transmission and hydraulic clutch while suppressing transmission failures and malfunctions.

[0007] (1) Based on the above findings, the control device for a four-wheel drive vehicle of the present invention comprises a first clutch for selectively disconnecting or connecting a power transmission path between a power source and a power transmission member, and a second clutch for selectively disconnecting or connecting a power transmission path between the power transmission member and a secondary drive wheel, and is capable of switching between a two-wheel drive state in which driving force is transmitted from the power source to the left and right main drive wheels by releasing at least one of the first clutch and the second clutch, and a four-wheel drive state in which driving force is transmitted from the power source to the left and right secondary drive wheels by engaging the first clutch and the second clutch, respectively, This invention relates to a four-wheel drive vehicle having an oil pump that operates using power output from a drive source and a transmission that operates using oil supplied by the oil pump, wherein at least one of the first clutch and the second clutch is a hydraulic clutch that operates using oil supplied by the oil pump, and is characterized by performing a starting control that prioritizes the supply of oil to the transmission over the supply of oil to the hydraulic clutch until the oil discharge amount from the oil pump reaches a predetermined standard amount, provided that the drive source starts outputting.

[0008] Based on the above-described findings, the control device for four-wheel drive vehicles of the present invention performs startup control that prioritizes the supply of oil to the transmission over the supply of oil to the hydraulic clutch until the oil discharge amount in the oil pump reaches a predetermined standard amount, provided that the power source starts outputting. Therefore, the control device for four-wheel drive vehicles of the present invention can stably control the operation of the transmission and the hydraulic clutch while suppressing failures and malfunctions of the transmission.

[0009] (2) The control device for a four-wheel drive vehicle of the present invention described above is characterized in that the starting control restricts the supply of oil to the hydraulic clutch by prohibiting or suppressing the supply of oil until the amount of oil discharged from the oil pump reaches a predetermined standard amount, and releases the clutch oil supply restriction on the condition that the amount of oil discharged from the oil pump reaches the standard amount.

[0010] The control device for four-wheel drive vehicles of the present invention, when performing startup control, prioritizes the supply of clutch oil over the supply of oil to the hydraulic clutch by restricting the supply of clutch oil until the amount of oil discharged from the oil pump reaches a predetermined standard amount. As a result, the control device for four-wheel drive vehicles of the present invention can prioritize the operation of the transmission, suppressing failures and malfunctions of the transmission while performing operation control. Furthermore, the control device for four-wheel drive vehicles of the present invention releases the restriction on the supply of clutch oil and starts the operation of the hydraulic clutch, provided that the amount of oil discharged from the oil pump reaches a standard amount. As a result, the control device for four-wheel drive vehicles of the present invention can also stably control the operation of the hydraulic clutch.

[0011] (3) The control device for a four-wheel drive vehicle of the present invention described above is characterized in that the driving force source is an engine, and the condition is met that the amount of oil discharged from the oil pump reaches a predetermined standard amount when the rotational speed of the engine is equal to or greater than a predetermined standard rotational speed, and that the starting control is performed using the rotational speed of the engine as an indicator.

[0012] The control device for four-wheel drive vehicles of the present invention can perform startup control using the engine speed as an indicator, based on the correlation between the engine speed, which is the driving force source, and the amount of oil discharged from the oil pump. Therefore, the control device for four-wheel drive vehicles of the present invention can appropriately control the supply of oil to the transmission and hydraulic clutch in accordance with the amount of oil discharged from the oil pump, without directly measuring the amount of oil discharged from the oil pump.

[0013] (4) The control device for a four-wheel drive vehicle of the present invention described above is characterized in that the reference amount is set to an amount of oil greater than or equal to the amount required in the transmission to suppress hardware failure of the transmission, and the starting control is performed by restricting the supply of clutch oil to the hydraulic clutch, which prohibits or restricts the supply of oil to the hydraulic clutch until the amount of oil discharged from the oil pump reaches the reference amount, and releasing the clutch oil supply restriction on the condition that the amount of oil discharged from the oil pump reaches the reference amount.

[0014] In the control device for four-wheel drive vehicles of the present invention, the reference amount is set to an amount of oil greater than or equal to the amount required by the transmission to suppress hardware failure of the transmission. Therefore, the control device for four-wheel drive vehicles of the present invention can supply sufficient oil to the transmission to suppress hardware failure before supplying oil to the hydraulic clutch. Accordingly, the control device for four-wheel drive vehicles of the present invention can stably control the operation of the transmission and the hydraulic clutch while suppressing failure of the transmission due to insufficient oil supply.

[0015] (5) The control device for a four-wheel drive vehicle of the present invention described above is characterized in that it performs an idle stop operation in which the four-wheel drive vehicle stops the drive source when predetermined idle stop conditions are met, and restarts the drive source when predetermined idle stop release conditions are met, and performs the startup control at the timing when the drive source restarts and begins outputting in conjunction with the idle stop operation.

[0016] The control device for four-wheel drive vehicles of the present invention, when a four-wheel drive vehicle performs an idle stop operation, performs startup control at the timing when the drive power source restarts and begins output in conjunction with the idle stop operation, thereby enabling stable control of the operation of the transmission and hydraulic clutch. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a control device for a four-wheel drive vehicle that can stably control the operation of the transmission and hydraulic clutch when the power source is started. [Brief explanation of the drawing]

[0018] [Figure 1] This is an explanatory diagram showing a control device according to one embodiment of the present invention and a vehicle equipped therewith. [Figure 2] This is a flowchart showing the startup control flow performed by a control device according to one embodiment of the present invention. [Figure 3] This is a timing chart corresponding to the control flow shown in Figure 2. [Modes for carrying out the invention]

[0019] Hereinafter, a control device for a four-wheel drive vehicle (control device 100) according to an embodiment of the present invention will be described with reference to the drawings, using a four-wheel drive vehicle (vehicle 10) employing it as an example. Before discussing the specific configuration of the control device 100 and the control performed by the control device 100, the general configuration of the vehicle 10 will be described below.

[0020] FIG. 1 is a diagram for explaining a schematic configuration of a vehicle 10 to which the present invention is applied. The vehicle 10 employs a front-engine rear-drive driving system. As shown in FIG. 1, the vehicle 10 includes a driving power source 12, a pair of left and right front wheels 14L and 14R, a pair of left and right rear wheels 16L and 16R, a power transmission device 18, a control device 100, and the like. The vehicle 10 is a four-wheel drive vehicle that can be appropriately switched between a two-wheel drive state in which driving force is transmitted to the rear wheels 16L and 16R to travel, and a four-wheel drive state in which driving force is transmitted to the front wheels 14L and 14R in addition to the rear wheels 16L and 16R to travel.

[0021] The driving power source 12 is for generating the driving power of the vehicle 10. The driving power source 12 can be constituted by, for example, an engine, a motor, or the like. Further, the front wheels 14L and 14R constitute auxiliary drive wheels in the vehicle 10. The front wheels 14L and 14R function as drive wheels in the four-wheel drive state and function as driven wheels in the two-wheel drive state. The rear wheels 16L and 16R constitute main drive wheels in the vehicle 10. The rear wheels 16L and 16R function as drive wheels in both the four-wheel drive state and the two-wheel drive state.

[0022] As shown in FIG. 1, the power transmission device 18 includes a transmission 20, a transfer 22, a front propeller shaft 24 (power transmission member), a rear propeller shaft 26, a differential gear device 28 for the front wheels, a differential gear device 30 for the rear wheels, a pair of left and right front wheel axles 32L and 32R, and a pair of left and right rear wheel axles 34L and 34R, and the like.

[0023] The power transmission device 18 can transmit the power generated by the drive power source 12 to the rear wheels 16L and 16R through a power transmission path that sequentially reaches the rear wheels 16L and 16R via the transfer 22, the rear propeller shaft 26, the differential gear device 30 for the rear wheels, the rear wheel axles 34L and 34R, etc. Further, the power transmission device 18 can also constitute a power transmission path that distributes and transmits a part of the drive power transmitted from the drive power source 12 to the transfer 22 to the front wheels 14L and 14R side. That is, the power transmission device 18 can transmit a part of the power generated by the drive power source 12 to the front wheels 14L and 14R through a power transmission path that sequentially reaches the front wheels 14L and 14R via the front propeller shaft 24, the differential gear device 28 for the front wheels, the front wheel axles 32L and 32R, etc. by adjusting the connection state of the clutch 46 for front-wheel drive, which will be described in detail later, from the transmission 20 through the transfer 22.

[0024] The transmission 20 operates by receiving the output from the drive power source 12 and is constituted by, for example, a conventionally known MT (manual transmission), AT (automatic transmission), CVT (continuously variable transmission), etc.

[0025] The transfer 22 has an input shaft 38, a rear-wheel side output shaft 40, a drive sprocket 42 for front-wheel drive, and a clutch 46 for front-wheel drive (first clutch) around the first rotation axis C1 inside the transfer case 36. Further, the transfer 22 has a front-wheel side output shaft 48 and a driven sprocket 50 for front-wheel drive around a second rotation axis C2 that extends in a direction along (substantially parallel in this embodiment) to the first rotation axis C1. Furthermore, the transfer 22 is configured such that a chain 52 for front-wheel drive is wound around the drive sprocket 42 for front-wheel drive and the driven sprocket 50 for front-wheel drive.

[0026] The input shaft 38 is connected to the transmission 20. This allows the input shaft 38 to receive power transmitted from the power source 12. The rear wheel output shaft 40 is connected to the rear propeller shaft 26 so as to transmit power. The front wheel drive sprocket 42 is supported on the rear wheel output shaft 40 so as to be rotatable relative to the rear wheel output shaft 40.

[0027] The front-wheel drive sprocket 42 can rotate integrally with the rear-wheel output shaft 40 by engaging the front-wheel drive clutch 46, and can transmit power to the front-wheel output shaft 48 via the front-wheel drive chain 52. Therefore, by engaging the front-wheel drive clutch 46, a portion of the driving force transmitted from the power source 12 to the rear propeller shaft 26 via the rear-wheel output shaft 40 can be distributed and transmitted to the front-wheel output shaft 48 via the front-wheel drive sprocket 42 and the front-wheel drive chain 52. On the other hand, by disengaging the front-wheel drive clutch 46, the driving force transmitted from the power source 12 to the rear-wheel output shaft 40 can be transmitted to the rear propeller shaft 26 without being transmitted (distributed) to the front-wheel drive sprocket 42.

[0028] The front-wheel drive clutch 46 is a hydraulic clutch. In this embodiment, a wet multi-plate clutch is used as the front-wheel drive clutch 46. The front-wheel drive clutch 46 is designed so that the transmission torque transmitted from the rear-wheel output shaft 40 to the front-wheel drive drive sprocket 42 can be adjusted by adjusting the degree of engagement. That is, the front-wheel drive clutch 46 functions as a clutch (first clutch) for selectively disconnecting or connecting the power transmission path between the drive source 12 and the front propeller shaft 24, which functions as a power transmission member to the front wheels 14L and 14R. The front-wheel drive clutch 46 is operated by hydraulic pressure, and the degree of engagement can be adjusted by controlling the magnitude of the hydraulic pressure.

[0029] The front wheel output shaft 48 is connected to the front propeller shaft 24 so as to transmit power. The front wheel drive driven sprocket 50 is provided so as to be able to rotate integrally with the front wheel output shaft 48. The front wheel drive chain 52 is wrapped around the front wheel drive sprocket 42 and the front wheel drive driven sprocket 50, and power can be transmitted between the two sprockets.

[0030] The front differential gear unit 28 is provided with a pinion shaft 82, a pair of side gears 84L and 84R, a pair of pinions 86a and 86b, and a ring gear 90 attached to a differential case 80. The pinions 86a and 86b are mounted to the differential case 80 with each pinion shaft 82 positioned at both ends. The side gears 84L and 84R are arranged opposite each other within the differential case 80 and mesh with the pinions 86a and 86b, respectively. The side gears 84L and 84R are connected to the front wheels 14L and 14R via the front axles 32L and 32R. The ring gear 90 is integrally mounted to the differential case 80. The front drive pinion 25, which is connected to the front propeller shaft 24, meshes with the ring gear 90. Furthermore, the front differential gear unit 28 is equipped with a meshing clutch 94 (second clutch). The meshing clutch 94 is designed to be engageable by applying pressure (negative pressure). The meshing clutch 94 functions as a second clutch that selectively disconnects or connects the power transmission path between the front propeller shaft 24, which functions as a power transmission member to the front wheels 14L and 14R, and the front axles 32L and 32R, which are auxiliary drive wheels.

[0031] The rear differential gear unit 30 is provided with a pinion shaft 122, a pair of side gears 124L and 124R, a pair of pinions 126a and 126b, and a ring gear 130 attached to the differential case 120. The pinions 126a and 126b are mounted to the differential case 120, with each pinion positioned at both ends of the pinion shaft 122. The side gears 124L and 124R are positioned opposite each other within the differential case 120 and mesh with the pinions 126a and 126b, respectively. The side gears 124L and 124R are connected to the rear wheels 16L and 16R via the rear axles 34L and 34R. The ring gear 130 is integrally mounted to the differential case 120. The rear drive pinion 27, which is connected to the rear propeller shaft 26, meshes with the ring gear 130.

[0032] Because the vehicle 10 has the configuration described above, when both the front-wheel drive clutch 46 and the meshing clutch 94 are connected (engaged) in a state that allows torque transmission, the power generated by the drive source 12 can be transmitted not only to the rear wheels 16L and 16R but also to the front wheels 14L and 14R (four-wheel drive state). On the other hand, if at least one of the front-wheel drive clutch 46 and the meshing clutch 94 of the vehicle 10 is disconnected (disengaged), the power transmission path to the front wheels 14L and 14R is cut off, and torque transmission becomes impossible. As a result, the vehicle 10 can transmit the power generated by the drive source 12 to the rear wheels 16L and 16R, but not to the front wheels 14L and 14R (two-wheel drive state).

[0033] Vehicle 10 is equipped with a selector switch 140 for switching the drive state. The selector switch 140 can be set to any of three drive states: "2WD", "4WD LOCK", and "4WD AUTO". When the selector switch 140 is set to "2WD", either or both of the front wheel drive clutch 46 and the meshing clutch 94 are disengaged. As a result, vehicle 10 is driven in a two-wheel drive state. When the selector switch 140 is set to "4WD LOCK", the meshing clutch 94 is engaged, and the front wheel drive clutch 46 is fully engaged. As a result, vehicle 10 is driven in a four-wheel drive state.

[0034] Furthermore, when the changeover switch 140 is set to "4WD AUTO", the drive control system is set to a state where it is possible to control the drive using a standby control method (variable drive distribution state) that increases the distribution of driving force transmitted to the front wheels 14L and 14R relative to the driving force transmitted to the rear wheels 16L and 16R by changing the engagement degree of the front wheel drive clutch 46 while engaging the mesh clutch 94, provided that slip is detected in the vehicle 10. Specifically, when the changeover switch 140 is set to "4WD AUTO", the mesh clutch 94 is engaged, and the front wheel drive clutch 46 is set to a standby state engaged at a predetermined standby engagement degree S in preparation for the occurrence of slip. When the changeover switch 140 is set to "4WD AUTO", if slip occurs in the main drive wheels, the rear wheels 16L and 16R, the drive state of the vehicle 10 is switched by fully engaging the front wheel drive clutch 46 while the mesh clutch 94 remains engaged.

[0035] Vehicle 10 is equipped with an oil pump 150. The oil pump 150 is capable of discharging oil by operating using power output from the engine, which is the drive source 12. The oil pump 150 is capable of supplying oil under pressure to the transmission 20 and the front-wheel drive clutch 46, which is composed of a hydraulic clutch.

[0036] The control device 100 is capable of controlling the connection state (engagement state) of the front-wheel drive clutch 46 and the meshing clutch 94 described above. The control device 100 is composed of a microcomputer equipped with, for example, a CPU, RAM, ROM, input / output interface, etc. The control device 100 includes a pump output sensing unit 102, a first clutch control unit 104 (first clutch control unit), and a second clutch control unit 106.

[0037] The pump output sensing unit 102 is for determining the cumulative amount of oil (oil discharge amount V) discharged by the oil pump 150 since the start of the drive power source 12. Here, the oil discharge amount V has a predetermined correlation with the engine speed N. Therefore, in this embodiment, the pump output sensing unit 102 can determine the amount of oil (oil discharge amount V) discharged by the oil pump 150 after the engine has started, using the engine speed N, which increases from a state where the engine, which is the drive power source 12, is stopped (a state where the rotation speed N is zero), as an indicator.

[0038] Specifically, the pump output sensing unit 102 can determine that the cumulative amount of oil discharged by the oil pump 150 after the engine starts (oil discharge amount V) has reached a predetermined reference amount Vs, provided that the rotational speed N of the drive power source 12 (engine) rotates from zero until it reaches or exceeds a predetermined reference rotational speed Ns. In this embodiment, the reference amount Vs is defined as an amount of oil greater than or equal to the amount required to suppress hardware failure of the transmission 20. Furthermore, the engine rotational speed N at the timing when the reference amount Vs of oil is discharged is defined as the reference rotational speed Ns.

[0039] The first clutch control unit 104 controls the transmitted torque (engagement degree of the first clutch) transmitted to the front propeller shaft 24 via the front wheel drive clutch 46. As described above, in this embodiment, the front wheel drive clutch 46 is a hydraulic clutch (wet multi-plate clutch) whose engagement degree (engagement pressure) can be adjusted by controlling the magnitude of the hydraulic pressure. Therefore, the first clutch control unit 104 controls the magnitude of the transmitted torque to the front propeller shaft 24 by controlling the magnitude of the hydraulic pressure acting on the front wheel drive clutch 46.

[0040] The second clutch control unit 106 controls the transmission of torque from the front wheel drive clutch 46 to the front wheel differential gear unit 28 by controlling the operation of the meshing clutch 94. As described above, the meshing clutch 94 is designed to be engageable by applying pressure (negative pressure). Therefore, the second clutch control unit 106 can switch the meshing clutch 94 between an engaged state and an unengaged state by controlling the magnitude of the pressure applied to the meshing clutch 94.

[0041] Here, the control device 100 described above is characterized in that, provided that the drive power source 12 starts outputting, it prioritizes the supply of oil to the transmission 20 over the supply of oil to the front wheel drive clutch 46, which is a hydraulic clutch, until the oil discharge amount from the oil pump 150 reaches a predetermined reference amount Vs. The starting control performed by the control device 100 will be explained in detail below, following the flowchart in Figure 2 and referring to the timing chart in Figure 3.

[0042] (Step 1) In step 1, the control device 100 checks whether the power source 12 of the vehicle 10 has started. If the power source 12 has already started or is stopped, the control flow remains in step 1. On the other hand, if the power source 12 starts to start, the control flow proceeds to step 2.

[0043] (Step 2) In step 2, the control device 100 uses the pump output sensing unit 102 to grasp the amount of oil discharged V from the oil pump 150 after the drive power source 12 has started, and confirms whether the amount of oil discharged V has reached a predetermined reference amount Vs. In this embodiment, as shown in Figure 3, the determination of whether the amount of oil discharged V has reached a predetermined reference amount Vs is made based on whether the rotational speed N of the engine constituting the drive power source 12 has reached a reference rotational speed Ns. If it is confirmed that the amount of oil discharged V has reached a predetermined reference amount Vs (in this embodiment, the rotational speed N of the engine has reached a reference rotational speed Ns), the control flow proceeds to step 4; otherwise, the control flow proceeds to step 3.

[0044] (Step 3) If the control flow proceeds to step 3, the oil discharge amount V is less than a predetermined reference amount Vs and does not reach the amount required to suppress hard failure of the transmission 20. Therefore, in step 3, the control device 100 restricts the clutch oil supply by prohibiting or suppressing (prohibiting in this embodiment) the supply of oil to the front wheel drive clutch 46, which is a hydraulic clutch. As a result, the oil discharged by the oil pump 150 is preferentially supplied to the transmission 20 over the front wheel drive clutch 46. After that, the control flow returns to step 2.

[0045] (Step 4) On the other hand, if it is confirmed in step 2 above that the oil discharge amount V has reached a predetermined reference amount Vs (in this embodiment, that the engine speed N has reached a reference speed Ns), the control device 100 releases the clutch oil supply restriction in step 4. This allows the engagement control of the front wheel drive clutch 46 to be performed according to the drive state set by the changeover switch 140, under the control of the first clutch control unit 104. In this state, the transmission 20 is already supplied with sufficient oil and is in a state where it can transmit power at a predetermined reduction ratio. Therefore, as shown in Figure 3, the vehicle 10 becomes capable of traveling at the desired speed. Once the control in step 4 is completed, the startup control shown in Figure 2 is completed.

[0046] The control device 100 mounted on the vehicle 10 described above has the following characteristic configurations (A) to (D), and is therefore capable of exhibiting distinctive effects. Furthermore, by configuring the control device 100 as shown in (E) below, distinctive effects that cannot be achieved with conventional technology can also be obtained.

[0047] (A) The control device 100 of this embodiment includes a front-wheel drive clutch 46 (first clutch) that selectively disconnects or connects the power transmission path between the drive source 12 and the front propeller shaft 24 (power transmission member), and a meshing clutch 94 (second clutch) that selectively disconnects or connects the power transmission path between the front propeller shaft 24 and the front wheels 14L, 14R (auxiliary drive wheels). By releasing at least one of the front-wheel drive clutch 46 and the meshing clutch 94, a two-wheel drive state is achieved in which driving force is transmitted from the drive source 12 to the left and right rear wheels 16L, 16R (main drive wheels), and the front The vehicle 10 is equipped with a four-wheel drive system that can switch between a four-wheel drive state, in which driving force is transmitted from the power source 12 to the left and right front wheels 14L and 14R by engaging a front-wheel drive clutch 46 and a meshing clutch 94, respectively, and a transmission 20 that operates using the oil supplied by the oil pump 150, wherein at least one of the front-wheel drive clutch 46 and the meshing clutch 94 is a hydraulic clutch that operates using the oil supplied by the oil pump 150. The control device 100 is equipped with a control device that, when the power source 12 starts outputting, prioritizes the supply of oil to the transmission 20 over the supply of oil to the hydraulic clutch until the oil discharge amount V from the oil pump 150 reaches a predetermined reference amount Vs.

[0048] The control device 100 of this embodiment performs startup control that prioritizes the supply of oil to the transmission 20 over the supply of oil to the front wheel drive clutch 46, which is a hydraulic clutch, until the oil discharge amount V in the oil pump 150 reaches a predetermined reference amount Vs (in this embodiment, until the rotational speed N of the engine constituting the drive power source 12 is equal to or greater than a predetermined reference rotational speed Ns), provided that the drive power source 12 starts outputting. Therefore, the control device 100 of this embodiment can stably control the operation of the transmission 20 and the front wheel drive clutch 46 while suppressing failures and malfunctions of the transmission 20.

[0049] In this embodiment, the rotational speed N of the engine constituting the driving force source 12 is set to be equal to or greater than a predetermined reference rotational speed Ns, which is used as a criterion for determining that the oil discharge amount V from the oil pump 150 has reached a predetermined reference amount Vs. However, the present invention is not limited to this. For example, it is possible to provide a sensor or the like that directly or indirectly measures the oil discharge amount V from the oil pump 150, and perform startup control based on the oil discharge amount V determined based on the output of the sensor or the like.

[0050] (B) The control device 100 of this embodiment performs clutch oil supply restriction during startup, which prohibits or suppresses the supply of oil to the hydraulic clutch until the oil discharge amount V from the oil pump 150 reaches a predetermined standard amount Vs, and releases the clutch oil supply restriction once the condition that the oil discharge amount V from the oil pump 150 reaches a standard amount Vs is met.

[0051] In this embodiment, the control device 100 restricts the clutch oil supply when performing startup control until the oil discharge amount V from the oil pump 150 reaches a predetermined standard amount Vs. This allows the control device 100 to prioritize the supply of oil to the hydraulic clutch (front-wheel drive clutch 46) over the transmission 20, thereby suppressing failures and malfunctions of the transmission 20 while performing operation control. Furthermore, once the oil discharge amount V from the oil pump 150 reaches the standard amount Vs and the transmission 20 is stable and no malfunctions occur, the control device 100 releases the clutch oil supply restriction and supplies oil to the front-wheel drive clutch 46. As a result, the control device 100 in this embodiment can also stably control the operation of the hydraulic clutch.

[0052] In this embodiment, an example was shown in which the clutch oil supply restriction is completely released on the condition that the oil discharge amount V in the oil pump 150 reaches a standard amount Vs. However, the present invention is not limited to this. For example, the control device 100 can release the clutch oil supply restriction in stages or continuously on the condition that the oil discharge amount V reaches a standard amount Vs.

[0053] (C) The control device 100 of this embodiment satisfies the condition that the oil discharge amount V from the oil pump 150 reaches a predetermined standard amount Vs when the engine speed N is equal to or greater than a predetermined standard speed Ns, and performs startup control using the engine speed N as an indicator.

[0054] The control device 100 of this embodiment can perform startup control using the engine speed N as an indicator, based on the correlation between the engine speed N, which is the driving force source 12, and the oil discharge amount V from the oil pump 150. Therefore, the control device 100 can appropriately control the supply of oil to the transmission 20 and the hydraulic clutch (front-wheel drive clutch 46) in accordance with the oil discharge amount V from the oil pump 150, without directly measuring the oil discharge amount V from the oil pump 150.

[0055] In this embodiment, an example is shown where the driving force source 12 is an engine, but the present invention is not limited to this, and it is possible to use a power source such as a motor as the driving force source 12. Even when the driving force source 12 is a motor or the like, if there is a certain correlation between the output characteristics of the motor or the like and the oil discharge amount V, it is preferable to estimate the oil discharge amount V based on that correlation and perform startup control based on the result.

[0056] (D) In ​​this embodiment, the control device 100 is configured such that the reference amount Vs is set to an amount of oil greater than or equal to the amount of oil required in the transmission 20 to suppress hard failure of the transmission 20, and the starting control is performed by restricting the supply of clutch oil to the hydraulic clutch (front wheel drive clutch 46) by prohibiting or suppressing the supply of oil until the oil discharge amount V from the oil pump 150 reaches the reference amount Vs, and releasing the clutch oil supply restriction on the condition that the oil discharge amount V from the oil pump 150 reaches the reference amount Vs.

[0057] In the control device 100 of this embodiment, since it is configured as described in (D) above, sufficient oil can be supplied to the transmission 20 to suppress hardware failures before supplying oil to the front wheel drive clutch 46. Therefore, the control device 100 can stably control the operation of the transmission 20 and the hydraulic front wheel drive clutch 46 while suppressing failures of the transmission 20 due to insufficient oil supply.

[0058] In this embodiment, the reference amount Vs is defined as an amount of oil greater than or equal to the amount required in the transmission 20 to suppress hardware failure of the transmission 20, but the present invention is not limited to this. For example, the reference amount Vs may be set to a predetermined amount that is higher or lower than the amount of oil required to suppress hardware failure of the transmission 20.

[0059] (E) The control device 100 of this embodiment described above is also applicable when the vehicle 10 performs an idle stop operation in which it stops the drive power source 12 when predetermined idle stop conditions are met, and restarts the drive power source 12 when predetermined idle stop release conditions are met. When the vehicle 10 performs an idle stop operation, it is preferable that the control device 100 performs startup control at the timing when the drive power source 12 restarts and begins output in conjunction with the idle stop operation.

[0060] If the vehicle 10 is equipped with an idle stop function, and the control device 100 performs startup control at the timing when the drive power source 12 restarts and begins outputting power in conjunction with the idle stop function, then the operation of the transmission 20 and the front-wheel drive clutch 46 can be stably controlled when the vehicle 10 restarts after it has stopped due to the idle stop function.

[0061] In this embodiment, as described above, a hydraulic clutch is used for the first clutch, the front-wheel drive clutch 46, and a mechanical clutch is used for the second clutch, the meshing clutch 94. However, a hydraulic clutch, such as the front-wheel drive clutch 46, may be used instead of the meshing clutch 94. Alternatively, a mechanical clutch, such as the meshing clutch 94, may be used instead of the first clutch, the front-wheel drive clutch 46, while a hydraulic clutch, such as the front-wheel drive clutch 46, may be used instead of the second clutch, the meshing clutch 94. In these cases, when either or both of the first and second clutches are hydraulic clutches, the supply of oil to the hydraulic clutch is subject to the startup control described above, thereby suppressing failures and malfunctions of the transmission 20 while stably controlling the operation of the transmission 20 and the hydraulic clutch.

[0062] The present invention is not limited to the embodiments and modifications described above, and other embodiments may be possible in the spirit and teachings thereof, without departing from the scope of the claims. The components of the embodiments described above may be arbitrarily selected and combined. Furthermore, any component of the embodiments may be arbitrarily combined with any component described in the means for solving the invention, or any component that embodies any component described in the means for solving the invention. We intend to obtain rights for these as well in amendments or divisional applications of this application. [Industrial applicability]

[0063] The present invention can be suitably used in control devices for four-wheel drive vehicles in general, which include a first clutch that selectively disconnects or connects the power transmission path between a drive source and a power transmission member, and a second clutch that selectively disconnects or connects the power transmission path between the power transmission member and a sub-drive wheel. [Explanation of Symbols]

[0064] 10: Vehicles (four-wheel drive vehicles) 12: Driving force source 14L, 14R: Front wheels (auxiliary drive wheels) 16L, 16R: Rear wheels (main drive wheels) 18: Power transmission device 24: Front propeller shaft (power transmission component) 46: Front-wheel drive clutch (first clutch) 94: Meshing clutch (second clutch) 100: Control device 102: Driving status monitoring unit 104: First clutch control unit

Claims

1. A first clutch that selectively disconnects or connects the power transmission path between the drive source and the power transmission member, The system includes a second clutch that selectively disconnects or connects the power transmission path between the power transmission member and the auxiliary drive wheel, A two-wheel drive state is achieved by releasing at least one of the first clutch and the second clutch, thereby transmitting driving force from the power source to the left and right main drive wheels, By engaging the first clutch and the second clutch, a four-wheel drive state is achieved in which driving force is transmitted from the driving force source to the left and right auxiliary drive wheels, The drive state can be switched, An oil pump that operates using power output from the aforementioned drive source, A transmission that operates using oil supplied by the aforementioned oil pump, It has, A control device for a four-wheel drive vehicle used in a four-wheel drive vehicle, wherein at least one of the first clutch and the second clutch is a hydraulic clutch that operates using oil supplied by the oil pump, A control device for a four-wheel drive vehicle, characterized in that, provided that the drive source starts outputting, regardless of the vehicle's driving state, it performs a starting control that prioritizes the supply of oil to the transmission over the supply of oil to the hydraulic clutch from the time the drive source starts outputting until the amount of oil discharged from the oil pump reaches a predetermined standard amount.

2. The aforementioned startup control, Until the oil discharge amount from the oil pump reaches a predetermined standard amount, the clutch oil supply restriction is performed by prohibiting or suppressing the supply of oil to the hydraulic clutch. The control device for a four-wheel drive vehicle according to claim 1, characterized in that the clutch oil supply restriction is released on the condition that the amount of oil discharged from the oil pump reaches the standard amount.

3. The aforementioned power source is an engine, The condition is met that the amount of oil discharged from the oil pump reaches a predetermined standard amount when the engine rotates from zero to a predetermined standard rotation speed or higher. A control device for a four-wheel drive vehicle according to claim 1 or 2, characterized in that it performs the startup control using the rotational speed of the engine as an indicator.

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