JP2019218032A - Control device of four-wheel drive vehicle - Google Patents

Abstract

To provide a control device of a four-wheel drive vehicle which can suitably suppress vibration and noise during the traveling of the vehicle.SOLUTION: When a rotational speed Ne of an engine 12 at the establishment of a changeover condition from a two-wheel drive mode to a four-wheel drive mode is within a resonance region of a propeller shaft 28 in the four-wheel drive mode which is set in advance, the changeover from the two-wheel drive mode to the four-wheel drive mode is prohibited. By this constitution, it is avoided that resonance is generated in the propeller shaft 28 accompanied by the changeover from the two-wheel drive mode to the four-wheel drive mode during the traveling of a vehicle, and the generation of vibration and noise during the traveling of the vehicle can be thereby suitably suppressed.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a technique for suitably suppressing vibration and noise during vehicle running in a four-wheel drive vehicle that selectively switches between a two-wheel drive mode and a four-wheel drive mode according to a running state.

  There is known a four-wheel drive vehicle that selectively switches between a two-wheel drive mode and a four-wheel drive mode according to a traveling state. For example, the four-wheel drive vehicle described in Patent Literature 1 is such a vehicle. In such a four-wheel drive vehicle, resonance may occur in the drive system depending on the rotation speed of the engine, and vibration and noise may be generated. On the other hand, in Patent Literature 1, when traveling in the two-wheel drive mode, when the rotational speed of the engine is in the region where the torsional resonance of the drive system from the engine to the propeller shaft occurs, the mode is switched from the two-wheel drive mode to the four-wheel drive mode. A control device for a four-wheel drive vehicle has been proposed.

JP 2008-100546 A

  By the way, as a four-wheel drive vehicle, a four-wheel drive vehicle provided with a clutch for selectively disconnecting or connecting a power transmission path between an engine and a propeller shaft is known. In such a four-wheel drive vehicle, a two-wheel drive mode in which the clutch is released and a four-wheel drive mode in which the clutch is engaged are selectively operated by a control device provided in the four-wheel drive vehicle in accordance with a traveling state. However, when switching from the two-wheel drive mode to the four-wheel drive mode, there is a problem that resonance occurs in the propeller shaft depending on the rotation speed of the engine, and relatively large vibration and noise are generated. .

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a control device for a four-wheel drive vehicle that can appropriately suppress vibration and noise during running of the vehicle. It is in.

  The gist of the first invention is as follows: (a) a pair of main drive wheels driven to rotate by an engine, a transfer for distributing a part of the driving force output from the engine to a pair of sub-drive wheels, A propeller shaft that transmits the driving force distributed from the transfer to the pair of auxiliary driving wheels, and a clutch that is provided on the transfer and selectively disconnects or connects a power transmission path between the engine and the propeller shaft. A four-wheel drive vehicle that switches between a two-wheel drive mode in which the clutch is disengaged and a four-wheel drive mode in which the clutch is engaged in accordance with the traveling state, The four-wheel drive in which the engine speed is preset when a switching condition for switching from the two-wheel drive mode to the four-wheel drive mode is satisfied. When in the resonance region of the propeller shaft in the dynamic mode is to prohibit the switching from the two-wheel drive mode to the four-wheel drive mode.

  According to the first invention, the rotation speed of the engine when the switching condition for switching from the two-wheel drive mode to the four-wheel drive mode is satisfied is set to a preset resonance region of the propeller shaft in the four-wheel drive mode. In some cases, switching from the two-wheel drive mode to the four-wheel drive mode is prohibited. This prevents the resonance of the propeller shaft from being caused by switching from the two-wheel drive mode to the four-wheel drive mode while the vehicle is running, so that the generation of vibration and noise during the vehicle running is appropriately suppressed. can do.

1 is a diagram schematically illustrating a configuration of a four-wheel drive vehicle to which the present invention is suitably applied. FIG. 2 is a diagram illustrating a configuration of a propeller shaft provided in the four-wheel drive vehicle of FIG. 1. FIG. 3 is a cross-sectional view illustrating a periphery of a second joint in the propeller shaft of FIG. 2. 4 is a flowchart illustrating an example of a switching operation in which the electronic control device of FIG. 1 selectively switches between a two-wheel drive mode and a four-wheel drive mode while the vehicle is traveling.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram schematically illustrating a configuration of a four-wheel drive vehicle 10 to which the present invention is suitably applied. In FIG. 1, a four-wheel drive vehicle 10 uses an engine 12 as a driving force source, and transmits a driving force (drive torque) of the engine 12 to a pair of left and right front wheels 14L and 14R corresponding to main driving wheels. An FF-based four-wheel drive device including a path and a second power transmission path for transmitting the driving force of the engine 12 to the pair of left and right rear wheels 16L and 16R corresponding to the auxiliary driving wheels. . In the two-wheel drive state of the four-wheel drive vehicle 10, the driving force transmitted from the engine 12 via the automatic transmission 18 is transmitted through the front-wheel driving force distribution unit 20, which is a differential device, and the left and right front wheel axles 22L, 22R. The power is transmitted to the pair of left and right front wheels 14L and 14R. That is, in the two-wheel drive state of the four-wheel drive vehicle 10, the engine 12 drives the pair of left and right front wheels 14 </ b> L and 14 </ b> R to rotate. In this two-wheel drive state, at least the first clutch (clutch) 24 is released, and no driving force is transmitted to the transfer 26, the propeller shaft 28, the rear-wheel driving force distribution unit 30, and the rear wheels 16L and 16R. However, in the four-wheel drive state, in addition to the two-wheel drive state, the first clutch 24 and the second clutch 32 are both engaged, so that the rear wheel is driven from the propeller shaft 28 through the rear wheel driving force distribution unit 30. The driving force from engine 12 is transmitted to 16L and 16R. The automatic transmission 18 is, for example, a belt-type continuously variable transmission (belt-type CVT). The automatic transmission 18 is provided on a power transmission path between the engine 12 and the front wheel driving force distribution unit 20. I have.

  As shown in FIG. 1, the front wheel driving force distribution unit 20, which is a differential device, includes a ring gear 20r rotatably provided around the first rotation axis C1 and meshing with an output gear 18a of the automatic transmission 18, and a ring gear 20r. It has a fixed differential case 20c and a differential gear mechanism 20d housed in the differential case 20c, and transmits the driving force from the engine 12 to the left and right front wheel axles 22L, 22R while allowing their differential rotation. I do. In the differential case 20c, inner peripheral meshing teeth 20a that mesh with outer circumferential meshing teeth 34a formed at the end of the first rotating member 34 provided on the transfer 26 on the front wheel 14L side are formed.

  As shown in FIG. 1, the transfer 26 has a first rotation member 34 and a second rotation member 36 formed with a ring gear 36 a that meshes with a driven pinion 28 a formed at an end of the propeller shaft 28 on the front wheel 14 L, 14 R side. A member 36 and the first clutch 24 which is a meshing dog clutch for selectively connecting and disconnecting power transmission between the first rotating member 34 and the second rotating member 36 are provided. Further, the transfer 26 allows the first rotating member 34 and the second rotating member 36 to be connected by the first clutch 24 so that power can be transmitted, so that a part of the driving force output from the engine 12 is transferred to the rear wheels 16L and 16L. 16R, that is, to the propeller shaft 28. The first clutch 24 selectively disconnects or connects power transmission between the engine 12 and the propeller shaft 28. Further, the propeller shaft 28 transmits the driving force distributed from the transfer 26 to the pair of left and right rear wheels 16L and 16R when the first clutch 24 and the second clutch 32 are engaged. The first rotating member 34 has first clutch teeth 34b formed at the end of the first rotating member 34 on the front wheel 14R side, and the second rotating member 36 has a front wheel 14R of the second rotating member 36. A second clutch tooth 36b is formed at the side end.

  As shown in FIG. 1, the first clutch 24 is formed with inner peripheral teeth 38 a which are always meshed with the first clutch teeth 34 b so as to be relatively movable in the direction of the first rotation axis C <b> 1 and can also be meshed with the second clutch teeth 36 b. The first movable sleeve 38 and the first movable sleeve 38 are moved in the direction of the first rotation axis C1 between a first meshing position meshing with the second clutch teeth 36b and a first non-meshing position not meshing with the second clutch teeth 36b. And a first actuator 40 that causes the first actuator 40 to operate. The first actuator 40 moves the first movable sleeve 38 between the first meshing position and the first non-meshing position by a first clutch drive current Ic1 supplied from an electronic control device (control device) 100 described later. Selectively move.

  The rear wheel driving force distribution unit 30 that distributes driving force from the propeller shaft 28 to the pair of left and right rear wheels 16 includes a rotating member 42 rotatably provided around a second rotation axis C2, a differential device 44, A second clutch 32 which is a meshing dog clutch for selectively connecting and disconnecting power transmission between the differential device 44 and the rotating member 42. The rotating member 42 has a ring gear 42a formed at an end on the rear wheel 16L side of the rotating member 42 and meshing with the drive pinion 28b of the propeller shaft 28, and an end formed on the rear wheel 16R side of the rotating member 42. Clutch teeth 42b. The differential device 44 includes a ring gear 44r rotatably provided around the second rotation axis C2, a differential case 44c to which the ring gear 44r is fixed, and a differential gear mechanism 44d housed in the differential case 44c. Have.

  As shown in FIG. 1, the second clutch 32 is formed with inner peripheral teeth 46a which are always meshed with the ring gear 44r of the differential device 44 so as to be relatively movable in the direction of the second rotation axis C2 and which can be meshed with the clutch teeth 42b. A second movable sleeve 46 and a second actuator for moving the second movable sleeve 46 in the direction of the second rotation axis C2 between a second meshing position meshing with the clutch teeth 42b and a second non-meshing position not meshing with the clutch teeth 42b. 48. The second actuator 48 selectively moves the second movable sleeve 46 between the second meshing position and the second non-meshing position by the second clutch drive current Ic2 supplied from the electronic control unit 100.

  As shown in FIGS. 1 and 2, the propeller shaft 20 has a shaft-shaped first shaft portion 28d connected to a driven pinion 28a by a first joint 28c so as to transmit power, and a drive pinion 28b by a third joint 28e. The second shaft portion 28f, the first shaft portion 28d, and the second shaft portion 28f, which are connected to each other so as to be able to transmit power, are relatively movable in the direction of the third rotation axis C3, and the first shaft portion 28d is A second joint 28g (see FIG. 2) for joining the shaft portion 28f with the shaft portion 28f such that the shaft portion 28f cannot rotate relatively around the third rotation axis C3. The first joint 28c and the third joint 28e are universal joints (cross joints). As shown in FIGS. 2 and 3, the second joint 28g is rotatably fitted to a tripod 28h, which is a tripod formed at the end of the first shaft 28d on the side of the second shaft 28f. A tripod joint that fits the three rollers 28i into three grooves 28k formed in a housing 28j provided at the end of the second shaft 28f on the first shaft 28d side.

  In the four-wheel drive vehicle 10 configured as described above, when the electronic control unit 100 switches from the two-wheel drive mode to the four-wheel drive mode according to, for example, a running state, the first clutch 24 and the second clutch 32 are engaged. The driving force is transmitted from the engine 12 to the pair of left and right front wheels 14L and 14R via the front wheel driving force distribution unit 20 and the like, and the pair of right and left rear wheels 16L and 16R is transmitted from the engine 12 via the propeller shaft 28 and the like. A four-wheel drive state in which the driving force is also transmitted is formed. That is, the four-wheel drive mode is a drive mode in which the first clutch 24 and the second clutch 32 are respectively engaged. Further, when the electronic control unit 100 switches from, for example, the four-wheel drive mode to the two-wheel drive mode, the first clutch 24 and the second clutch 32 are respectively released, and the left and right wheels are separated from the engine 12 via the front wheel driving force distribution unit 20. A two-wheel drive state in which the driving force is transmitted to the pair of front wheels 14L and 14R is formed. That is, the two-wheel drive mode is a drive mode in which the first clutch 24 and the second clutch 32 are respectively released. In the first clutch 24, when the first movable sleeve 38 moves to the first meshing position, the first clutch 24 is engaged, and when the first movable sleeve 38 moves to the first non-meshing position, the first clutch 24 moves. Release. In the second clutch 32, when the second movable sleeve 46 moves to the second meshing position, the second clutch 32 is engaged, and when the second movable sleeve 46 moves to the second non-meshing position, the second clutch 32 Release.

  As shown in FIG. 1, the electronic control unit 100 provided in the four-wheel drive vehicle 10 includes a so-called microcomputer having, for example, a CPU, a RAM, a ROM, an input / output interface, and the like. Various controls of the four-wheel drive vehicle 10 are executed by performing signal processing in accordance with a program stored in the ROM in advance while utilizing the temporary storage function of (1). The electronic control unit 100 is supplied with various input signals detected by respective sensors provided in the four-wheel drive vehicle 10. For example, an ON / OFF signal indicating whether the first clutch 24 detected by the first position sensor 50 is engaged, that is, ON indicating whether the first movable sleeve 38 is at the first meshing position, An OFF signal and ON / OFF signals indicating whether the second clutch 32 detected by the second position sensor 52 is engaged, that is, indicating whether the second movable sleeve 46 is at the second meshing position. An ON / OFF signal, a signal representing the vehicle speed V (km / h) detected by the vehicle speed sensor 54, and a signal representing the rotational speed Ne (rpm) of the engine 12 detected by the engine rotational speed sensor 56 are electronically. It is input to the control device 100.

  Further, various output signals are supplied from the electronic control unit 100 to each device provided in the four-wheel drive vehicle 10. For example, the first clutch drive current Ic1 supplied to the first actuator 40 to engage or disengage the first clutch 24, and the second clutch 48 is supplied to the second actuator 48 to engage or disengage the second clutch 32. The second clutch drive current Ic2 is supplied from the electronic control unit 100 to each unit.

  As shown in FIG. 1, the electronic control unit 100 includes, for example, a 2WD determining unit 60, a mode switching condition satisfaction determining unit 62, a mode switching prohibition determining unit 64, a mode switching control unit 66, and a clutch control unit 68. And are provided.

  The 2WD determination unit 60 determines whether or not the vehicle is traveling in a two-wheel drive state in which the driving force from the engine 12 is transmitted to only the pair of left and right front wheels 14L and 14R. For example, the 2WD determination unit 60 detects that the first movable sleeve 38 is not at the first meshing position by the first position sensor 50, and that the second movable sleeve 46 is not at the second meshing position by the second position sensor 52. Is detected, it is determined that the vehicle is traveling in the two-wheel drive state. In addition, for example, the 2WD determination unit 60 detects that the first movable sleeve 38 is at the first meshing position by the first position sensor 50, and moves the second movable sleeve 46 to the second meshing position by the second position sensor 52. , The vehicle is not traveling in the two-wheel drive state, that is, traveling in the four-wheel drive state in which the driving force from the engine 12 is transmitted to the pair of left and right front wheels 14L, 14R and the pair of left and right rear wheels 16L, 16R. Is determined.

  When the 2WD determination unit 60 determines that the vehicle is traveling in the two-wheel drive state, the mode switching condition establishment determination unit 62 determines whether a switching condition for switching from the two-wheel drive mode to the four-wheel drive mode is satisfied. For example, when the vehicle speed V (km / h) becomes lower than a predetermined vehicle speed Vc (km / h), the mode switching condition establishment determination unit 62 establishes a switching condition for switching from the two-wheel drive mode to the four-wheel drive mode. It is determined that it has been done.

  When the 2WD determining unit 60 determines that the vehicle is traveling in the four-wheel drive state, the mode switching condition establishment determination unit 62 determines whether the switching condition for switching from the four-wheel drive mode to the two-wheel drive mode is satisfied. judge. For example, when the vehicle speed V (km / h) becomes equal to or higher than the predetermined vehicle speed Vc (km / h), the mode switching condition establishment determination unit 62 determines that the switching condition for switching from the four-wheel drive mode to the two-wheel drive mode is satisfied.

  The mode switching prohibition determination unit 64 prohibits the switching from the two-wheel drive mode to the four-wheel drive mode when the mode switching condition satisfaction determination unit 62 determines that the switching condition for switching from the two-wheel drive mode to the four-wheel drive mode is satisfied. It is determined whether or not to perform. For example, the mode switching prohibition determination unit 64 determines the rotation speed Ne (rpm) of the engine 12 when the switching condition for switching from the two-wheel drive mode to the four-wheel drive mode is satisfied. From the rotation speed Ne (rpm) of the engine 12 when the switching condition for switching from the two-wheel drive mode to the four-wheel drive mode is satisfied in the resonance region of the propeller shaft 28 in FIG. When the subtracted absolute value (| Ne-α |) is within a first threshold L1 (rpm) set in advance (| Ne-α | ≦ L1), switching from the two-wheel drive mode to the four-wheel drive mode is prohibited. I do. In the four-wheel drive state in which the first clutch 24 and the second clutch 32 are engaged, the first resonance rotation speed α (rpm) is a belt-type vibration caused by the explosion vibration of the engine 12 and the rotation of the engine 12. The rotational speed Ne of the engine 12 at which resonance occurs in the propeller shaft 28 due to belt vibration or the like in the automatic transmission 18 that is a CVT. When the rotation speed Ne of the engine 12 approaches the first resonance rotation speed α in the four-wheel drive state, resonance occurs between the second joint 28g and the third joint 28e of the propeller shaft 28, and for example, the propeller shaft The bending vibration of the second joint 28g and the rattling at the second joint 28g are caused.

  When the mode switching condition determination unit 62 determines that the switching condition for switching from the four-wheel drive mode to the two-wheel drive mode is satisfied, the mode switching prohibition determining unit 64 switches from the four-wheel drive mode to the two-wheel drive mode. It is determined whether or not to prohibit. For example, the mode switching prohibition determining unit 64 determines whether the rotation speed Ne (rpm) of the engine 12 when the switching condition for switching from the four-wheel drive mode to the two-wheel drive mode is satisfied is a preset two-wheel drive mode, that is, a two-wheel drive state. The second resonance rotational speed β (rpm) is subtracted from the rotational speed Ne (rpm) of the engine 12 when the propeller shaft 28 is in the resonance region, that is, when the switching condition for switching from the four-wheel drive mode to the two-wheel drive mode is satisfied. When the absolute value (| Ne-β |) is within the second threshold L2 (rpm) set in advance (| Ne-β | ≦ L2), switching from the four-wheel drive mode to the two-wheel drive mode is prohibited. In the two-wheel drive state in which the first clutch 24 and the second clutch 32 are disengaged, the second resonance rotational speed β transmits the driving force of the engine 12 to the propeller shaft 28 by disengaging the first clutch 24. However, the vibration itself is not interrupted, and the belt vibration and the like in the automatic transmission 18 of the belt type CVT accompanying the rotation of the engine 12 are transmitted to the propeller shaft 28, and the vibration accompanying the explosion of the engine 12 The rotational speed Ne of the engine 12 at which resonance occurs in the propeller shaft 28 due to transmission to the propeller shaft 28 via the case of the transfer 26 or transmission of the roll motion in the front-rear direction of the engine 12 to the propeller shaft 28. It is. When the rotation speed Ne of the engine 12 approaches the second resonance rotation speed β in the two-wheel drive state, for example, bending vibration of the propeller shaft 28 occurs between the first joint 28c and the second joint 28g of the propeller shaft 28. I do.

  The mode switching control unit 66 determines that the switching condition for switching from the two-wheel drive mode to the four-wheel drive mode is satisfied by the mode switching condition satisfaction determination unit 62, and the mode switching prohibition determination unit 64 changes the two-wheel drive mode to the four-wheel drive mode. When it is determined that the switching to the mode is prohibited, the switching from the two-wheel drive mode to the four-wheel drive mode is prohibited, and the two-wheel drive mode is continuously selected. Further, the mode switching control unit 66 determines that the switching condition for switching from the two-wheel drive mode to the four-wheel drive mode is satisfied by the mode switching condition satisfaction determination unit 62, and the mode switching prohibition determination unit 64 switches the two-wheel drive mode to the four-wheel drive mode. If it is determined that the switching to the wheel drive mode is not prohibited, the four-wheel drive mode is selected, that is, the mode is switched from the two-wheel drive mode to the four-wheel drive mode. The mode switching control unit 66 determines that the vehicle is traveling in the two-wheel drive state by the 2WD determination unit 60, and the switching condition for switching from the two-wheel drive mode to the four-wheel drive mode is satisfied by the mode switching condition satisfaction determination unit 62. If it is determined that it has not been performed, the two-wheel drive mode is continuously selected.

  In addition, the mode switching control unit 66 determines that the switching condition for switching from the four-wheel drive mode to the two-wheel drive mode is satisfied by the mode switching condition satisfaction determination unit 62, and the mode switching prohibition determination unit 64 switches the four-wheel drive mode from the four-wheel drive mode. When it is determined that the switching to the two-wheel drive mode is prohibited, the switching from the four-wheel drive mode to the two-wheel drive mode is prohibited, and the four-wheel drive mode is continuously selected. In addition, the mode switching control unit 66 determines that the switching condition for switching from the four-wheel drive mode to the two-wheel drive mode is satisfied by the mode switching condition satisfaction determination unit 62, and the mode switching prohibition determination unit 64 switches the four-wheel drive mode from the four-wheel drive mode. When it is determined that the switching to the two-wheel drive mode is not prohibited, the two-wheel drive mode is selected, that is, the four-wheel drive mode is switched to the two-wheel drive mode. The mode switching control unit 66 determines that the vehicle is traveling in the four-wheel drive state by the 2WD determination unit 60 and that the mode switching condition satisfaction determination unit 62 determines that the switching condition for switching from the four-wheel drive mode to the two-wheel drive mode is satisfied. When it is determined that the condition is not established, the four-wheel drive mode is continuously selected.

  When the two-wheel drive mode is selected by the mode switching control unit 66, the clutch control unit 68 releases the first clutch drive current Ic1 and the second clutch drive current Ic2 so as to release the first clutch 24 and the second clutch 32, respectively. Control. Also, when the four-wheel drive mode is selected by the mode switching control unit 66, the clutch control unit 68 causes the first clutch drive current Ic1 and the second clutch drive current Ic1 to engage the first clutch 24 and the second clutch 32, respectively. The clutch drive current Ic2 is controlled.

  FIG. 4 is a flowchart illustrating an example of a switching operation of the electronic control device 100 for selectively switching between the two-wheel drive mode and the four-wheel drive mode while the vehicle is traveling.

  First, in step S1 corresponding to the function of the 2WD determination unit 60 (hereinafter, step is omitted), it is determined whether the vehicle is traveling in the two-wheel drive state. When the determination in S1 is affirmative, that is, when the vehicle is traveling in the two-wheel drive state, S2 corresponding to the function of the mode switching condition satisfaction determination unit 62 is executed, and when the determination in S1 is negative, that is, in four-wheel drive. If the vehicle is traveling in the state, S3 corresponding to the function of the mode switching condition satisfaction determination unit 62 is executed.

  In S2, it is determined whether a switching condition for switching from the two-wheel drive mode to the four-wheel drive mode is satisfied. When the determination in S2 is affirmative, S4 corresponding to the function of the mode switching prohibition determining unit 64 is performed, but when the determination in S2 is negative, the function corresponding to the function of the mode switching control unit 66 is performed. S5 is executed. In S4, it is determined whether or not to prohibit switching from the two-wheel drive mode to the four-wheel drive mode, that is, the absolute value obtained by subtracting the first resonance rotation speed α from the rotation speed Ne of the engine 12 when the determination in S2 is affirmed. Is determined to be within a first threshold value L1 set in advance. When the determination in S4 is affirmative, that is, when switching from the two-wheel drive mode to the four-wheel drive mode is prohibited, S5 is executed, and when the determination in S4 is negative, that is, from the two-wheel drive mode to the four-wheel drive mode. If the switching is not prohibited, S3 is executed.

  In S3, it is determined whether a switching condition for switching from the four-wheel drive mode to the two-wheel drive mode is satisfied. If the determination in S3 is affirmative, S6 corresponding to the function of the mode switching prohibition determining unit 64 is performed, but if the determination in S3 is negative, the function corresponds to the function of the mode switching control unit 66. S7 is executed. In S6, it is determined whether or not the switching from the four-wheel drive mode to the two-wheel drive mode is prohibited, that is, the absolute value obtained by subtracting the second resonance rotation speed β from the rotation speed Ne of the engine 12 when the determination in S3 is affirmed. Is determined to be within a second threshold L2 set in advance. If the determination in S6 is affirmative, that is, if switching from the four-wheel drive mode to the two-wheel drive mode is prohibited, S7 is executed, but if the determination in S6 is negative, that is, from the four-wheel drive mode to the two-wheel drive mode. If the switching to the mode is not prohibited, S5 is executed. In S5, the two-wheel drive mode is selected. In S7, the four-wheel drive mode is selected.

  As described above, according to the electronic control device 100 of the four-wheel drive vehicle 10 of the present embodiment, the rotation speed Ne of the engine 12 when the switching condition for switching from the two-wheel drive mode to the four-wheel drive mode is satisfied is set in advance. When the propeller shaft 28 is in the resonance region in the four-wheel drive mode, switching from the two-wheel drive mode to the four-wheel drive mode is prohibited. This prevents the resonance of the propeller shaft 28 from occurring when the mode is switched from the two-wheel drive mode to the four-wheel drive mode while the vehicle is running, so that the generation of vibration and noise during the running of the vehicle is appropriately suppressed. can do.

  Although the embodiments of the present invention have been described in detail with reference to the drawings, the present invention is applicable to other aspects.

  For example, although the above-described four-wheel drive vehicle 10 includes the first clutch 24 and the second clutch 32, for example, the second clutch 32 is removed from the four-wheel drive vehicle 10 and the propeller shaft 28 is connected to the differential device 44. May be connected to the ring gear 44r so that power can be transmitted. That is, the four-wheel drive state may be formed by engaging the first clutch 24, and the two-wheel drive state may be formed by releasing the first clutch 24. The first clutch 24 and the second clutch 32 provided in the four-wheel drive vehicle 10 are mesh dog clutches, but may be other clutches, such as a friction clutch.

  The automatic transmission 18 provided in the four-wheel drive vehicle 10 is a belt-type continuously variable transmission (belt-type CVT), but other automatic transmissions such as a planetary gear-type stepped transmission. And so on. That is, when the rotation speed Ne of the engine 12 approaches the first resonance rotation speed α (in the four-wheel drive state) or the second resonance rotation speed β (in the two-wheel drive state), the automatic transmission 18 changes to the belt-type continuously variable transmission. In other automatic transmissions, resonance occurs in the propeller shaft 28.

  In the flowchart of FIG. 4, if it is determined in S4 that the switching from the two-wheel drive mode to the four-wheel drive mode is not prohibited, that is, if the determination in S4 is negative, S3 has been executed. May be executed if S is denied.

  The above description is merely an embodiment, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art.

10: Four-wheel drive vehicle 12: Engines 14L, 14R: Front wheels (main drive wheels)
16L, 16R: rear wheels (auxiliary drive wheels)
24: first clutch (clutch)
26: transfer 28: propeller shaft 64: mode switching prohibition determining unit 66: mode switching control unit 62: mode switching condition satisfaction determining unit 100: electronic control device (control device)
Ne: rotation speed

Claims (1)

A pair of main driving wheels that are rotationally driven by the engine, a transfer that distributes a part of the driving force output from the engine to a pair of sub driving wheels, and a driving force that is distributed from the transfer and the pair of sub driving A four-wheel drive vehicle including a propeller shaft that transmits to wheels, and a clutch that is provided on the transfer and that selectively disconnects or connects a power transmission path between the engine and the propeller shaft. A four-wheel drive vehicle control device that switches between a two-wheel drive mode in which the clutch is released and a four-wheel drive mode in which the clutch is engaged,
When the rotation speed of the engine is in a preset resonance region of the propeller shaft in the four-wheel drive mode when a switching condition for switching from the two-wheel drive mode to the four-wheel drive mode is satisfied, the two-wheel drive mode A control device for a four-wheel drive vehicle, wherein switching to the four-wheel drive mode is prohibited.

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