Dog clutch engagement control system

Abstract

To provide a meshing clutch engagement control system for improving responsiveness of clutch engagement.SOLUTION: The clutch phase difference can be calculated based on the detection value of the phase difference sensor. The control device performs a synchronization operation for causing the input / output shaft rotation speed difference to reach the target rotation speed difference in accordance with the engagement instruction. The control device outputs a drive instruction to the clutch actuator so as to engage the dog clutch at an engagement timing at which the dog clutch is in a clutch phase difference in which the dog clutch can be engaged. Based on the clutch phase difference detected during the synchronization operation or after the completion of the synchronization operation, the control device determines whether the forward rotation mode (output shaft rotation speed>input shaft rotation speed) or the reverse rotation mode (output shaft rotation speed<input shaft rotation speed) is the early arrival rotation mode in which the arrival time to the engagement timing is shorter. When the current rotation mode is different from the early arrival rotation mode, the control device controls the input / output shaft rotation speed difference so as to switch from the current rotation mode to the early arrival rotation mode.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a dog clutch engagement control system. [Background technology]

[0002] 2. Description of the Related Art Conventionally, a dog clutch engagement control system is known that engages an input shaft and an output shaft that rotate at different rotational speeds in a released state.

[0003] For example, Patent Document 1 discloses a technology for predicting future engagement times based on multiple past engagement times (meshing timings) detected from the output of a phase difference sensor. The control device performs a synchronization operation so that the rotational speed difference between the motor and the axle (i.e., the input / output shaft rotational speed difference) reaches a predetermined target rotational speed difference. Then, the control device drives the clutch actuator in advance so that the dog clutch will engage at the predicted engagement time after the input / output shaft rotational speed difference reaches the target rotational speed difference. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-025561 Summary of the Invention [Problem to be solved by the invention]

[0005] In the technology of Patent Document 1, the control device stores multiple past engagement times and calculates an approximate line passing through each point to predict future engagement times. Because future engagement times are predicted by approximation from past engagement times, the error from actual operation increases, and responsiveness to engagement commands decreases.

[0006] Here, we focus on the clutch phase difference between the first clutch member connected to the input shaft and the second clutch member connected to the output shaft. If we define a state in which the rotational phases of the engagement teeth of both clutch members are the same as "clutch phase difference = 0," then the first clutch member and the second clutch member can be engaged when the clutch phase difference is ±1 / 2 of the pitch angle of the engagement teeth. Therefore, to improve clutch engagement responsiveness, it is necessary to quickly reach the state of "clutch phase difference = ±(1 / 2) × pitch angle" after the input / output shaft rotational speed difference reaches the target rotational speed difference.

[0007] The present invention was created in consideration of the above points, and its object is to provide a dog clutch engagement control system that improves the responsiveness of clutch engagement by appropriately controlling the difference in input and output shaft rotational speed. [Means for solving the problem]

[0008] The dog clutch engagement control system (100) of the present invention includes a dog clutch (10), a clutch actuator (5), a phase difference sensor (6), and a control device (7).

[0009] The dog clutch has a first clutch member (11) and a second clutch member (12), and the first clutch member and the second clutch member are switched between an engaged state and a released state. The first clutch member is connected to an input shaft (3) and has a plurality of first engagement teeth (13) arranged in the circumferential direction. The second clutch member is connected to an output shaft (4) and has a plurality of second engagement teeth (14) arranged in the circumferential direction, which can mesh with the first engagement teeth directly or via an intermediate member. In a dog clutch engagement control system mounted on a vehicle, the input shaft is connected to a motor or an internal combustion engine, for example, via a reducer. The output shaft is connected to drive wheels via an axle.

[0010] The clutch actuator moves the first clutch member and the second clutch member relative to each other in the axial direction, or, if an intermediate member is used, moves the intermediate member relative to the first clutch member and the second clutch member in the axial direction.

[0011] The phase difference sensor detects the phase (θ1) of the first clutch member and the phase (θ2) of the second clutch member. Based on the detected values, the clutch phase difference, which is the phase difference between the first clutch member and the second clutch member, can be calculated. The phase difference sensor itself may calculate and output the clutch phase difference, or a control device that acquires the output of the phase difference sensor may calculate the clutch phase difference.

[0012] The control device controls the input / output shaft rotation speed difference (ΔN, ω), which is the difference between the rotation speed of the output shaft (Nout) and the rotation speed of the input shaft (Nin).The control device performs a synchronization operation by issuing an engagement command to engage the released dog clutch, thereby reducing the absolute value of the input / output shaft rotation speed difference and reaching the target rotation speed difference (ωs, -ωs).The control device outputs a drive command to the clutch actuator to engage the dog clutch at an engagement time that provides a clutch phase difference that allows the dog clutch to be engaged.

[0013] A rotation mode in which the rotation speed of the output shaft is greater than the rotation speed of the input shaft is defined as a positive rotation mode, and a rotation mode in which the rotation speed of the output shaft is smaller than the rotation speed of the input shaft is defined as a negative rotation mode.

[0014] The control device performs an early-arrival determination based on the clutch phase difference detected during or after the synchronization operation, determining whether the forward rotation mode or the negative rotation mode is the early-arrival rotation mode, which has a shorter time until engagement. When the current rotation mode is different from the early-arrival rotation mode, the control device controls the input / output shaft rotation speed difference so as to switch from the current rotation mode to the early-arrival rotation mode.

[0015] For example, in a moving vehicle, when the motor speed is increased to engage the first clutch member on the input shaft side with respect to the second clutch member on the rotating axle (output shaft), a synchronization operation is performed in forward rotation mode to bring the input / output shaft speed difference to a target speed difference. If the negative rotation mode is determined to be the early rotation mode based on the clutch phase difference during or after the synchronization operation is completed, the control device increases the input shaft speed relative to the output shaft speed to switch from the current forward rotation mode to the negative rotation mode. This shortens the time until clutch engagement and improves responsiveness. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram showing an example of the configuration of a vehicle to which a dog clutch engagement control system is applied; [Figure 2] Schematic diagram showing switching between 2WD and 4WD. [Figure 3] 5A and 5B are diagrams illustrating a clutch engagement operation when switching from 2WD to 4WD. [Figure 4] FIG. 4 is a schematic diagram showing state transitions of a dog clutch. [Figure 5] FIG. 2 is a diagram illustrating the configuration of a dog clutch engagement control system according to the present embodiment. [Figure 6] FIG. 4 is a diagram illustrating the definition of a clutch phase difference in the present embodiment. [Figure 7] FIG. 4 is a waveform diagram of each phase of the first clutch member and the second clutch member. [Figure 8] 6 is a diagram comparing the clutch phase difference detection timing between the present embodiment and a comparative example. FIG. [Figure 9] 5 is a diagram illustrating selection of a positive rotation mode or a negative rotation mode according to a clutch phase difference. FIG. [Figure 10] 4 is a time chart of clutch engagement control according to the first embodiment. [Figure 11] 4 is a time chart of clutch engagement control according to the first embodiment. [Figure 12] 4 is a flowchart of clutch engagement control according to the first embodiment. [Figure 13]10 is a time chart of clutch engagement control according to the second embodiment. [Figure 14] 10 is a flowchart of clutch engagement control according to a second embodiment. [Figure 15] FIG. 10 is an explanatory diagram of a phase change amount calculation method in the second embodiment. [Figure 16] 10 is a time chart of clutch engagement control according to the third embodiment. [Figure 17] 10 is a flowchart of clutch engagement control according to a third embodiment. [Figure 18] FIG. 11 is an explanatory diagram of a phase change amount calculation method in the third embodiment. [Figure 19] 10 is a time chart of clutch engagement control according to a modification of the third embodiment. [Figure 20] FIG. 11 is an explanatory diagram of a phase change amount calculation method in a modified example of the third embodiment. [Figure 21] 10 is a time chart of clutch engagement control according to the fourth embodiment. [Figure 22] 10 is a flowchart of clutch engagement control according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] A dog clutch engagement control system according to multiple embodiments of the present invention will be described with reference to the drawings. The basic system configurations of the first to fourth embodiments are the same, but the control configurations by the control device are different. The first to fourth embodiments are collectively referred to as "the present embodiment." The dog clutch engagement control system of the present embodiment is a system that, when a dog clutch provided in a vehicle powertrain system is in a released state, drives a clutch actuator in accordance with the engagement timing to engage the dog clutch.

[0018] [Vehicle, dog clutch engagement control system] 1 and 2, a configuration example of a vehicle 90 to which a dog clutch engagement control system is applied will be described. This vehicle 90 is an electric vehicle powered by two MGs (motor generators): a front-wheel MG 81 and a rear-wheel MG 82. The MGs 81 and 82 function as electric motors during power running and as generators during regenerative running. This vehicle 90 can switch between two-wheel drive (2WD) using only the front wheels 91 and four-wheel drive (4WD) using the front wheels 91 and the rear wheels 92.

[0019] The front-wheel MG 81 is always connected to the front wheels 91 via a differential 93 and a connecting shaft 95. Therefore, the front wheels 91 are always driven wheels. Meanwhile, a dog clutch 10 is provided in the power transmission path from the rear-wheel MG 82 to the rear wheels 92. In the example shown in FIG. 1 , the dog clutch 10 is provided between the rear-wheel MG 82 and the differential 94, but the dog clutch 10 may be provided closer to the rear wheels 92 than the differential 94.

[0020] When the dog clutch 10 is in a disengaged state, the rear wheel MG 82 is not connected to the rear wheels 92, and the rear wheels 92 rotate as driven wheels of the front wheels 91. When the dog clutch 10 is in an engaged state, the rear wheel MG 82 is connected to the rear wheels 92 via a differential 94 and a connecting shaft 96. At this time, the rear wheels 92 become driving wheels in addition to the front wheels 91. It should be noted that speed reducers 87, 88 may be provided on the output shafts of the front wheel MG 81 and the rear wheel MG 82, respectively.

[0021] In this way, the vehicle 90 switches between 2WD and 4WD by switching the dog clutch 10 between the released and engaged states. For example, 2WD with 1MG driving is selected on flat roads with low load, and 4WD with 2MG driving is selected on slopes where high driving force is required. When switching from 4WD to 2WD, it is necessary to reduce drag loss by disengaging the clutch and improve power consumption. When switching from 2WD to 4WD, it is necessary to achieve responsive acceleration performance by engaging a highly responsive clutch. If clutch engagement is delayed, the torque response of the disengaged rear wheel MG82 is delayed, which delays the torque response of the entire vehicle. As a result, torque response to the driver's accelerator operation is delayed, affecting drivability.

[0022] When a higher-level vehicle control device (not shown) determines that a switch from 2WD to 4WD is necessary based on the vehicle's driving state, external environment such as the road surface, or a driver's instruction, it sends an engagement command to dog clutch engagement control system 100. When dog clutch engagement control system 100 receives the engagement command when dog clutch 10 is released, it engages dog clutch 10. Dog clutch engagement control system 100 includes dog clutch 10, clutch actuator 5, phase difference sensor 6, and control device 7. In the following specification and drawings, clutch actuator 5 may be referred to as "ACT" as appropriate.

[0023] The dog clutch 10 has a first clutch member 11 connected to the input shaft 3 and a second clutch member 12 connected to the output shaft 4. The first clutch member 11 has a plurality of first engagement teeth 13 arranged in the circumferential direction and rotates about its axis. The second clutch member 12 has second engagement teeth 14 formed in the circumferential direction that can directly mesh with the first engagement teeth 13 and rotates coaxially and in the same direction as the first clutch member 11. The dog clutch engagement control system 100 of this embodiment is mounted on a vehicle 90 whose output shaft 4 is connected to rear wheels 92, which are drive wheels. In the configuration example of FIG. 1 , a reducer 88 is provided between the rear-wheel MG 82 and the first clutch member 11. The rotation of a motor shaft 83 of the rear-wheel MG 82 is reduced in speed by the reducer 88 and transmitted to the input shaft 3.

[0024] The clutch actuator 5 moves the first clutch member 11 and the second clutch member 12 relative to each other in the axial direction. The clutch actuator 5 is not limited to being provided on the first clutch member 11 side, but may also be provided on the second clutch member 12 side. When the first clutch member 11 and the second clutch member 12 move toward each other, they enter an engaged state in which the first engagement teeth 13 and the second engagement teeth 14 mesh with each other. When the first clutch member 11 and the second clutch member 12 move away from each other, they enter a released state in which they are no longer meshed with each other. In other words, the relative axial movement of the first clutch member 11 and the second clutch member 12 switches between the engaged state and the released state of the first clutch member 11 and the second clutch member 12. Note that a sleeve-type clutch other than this type of clutch will be described in the "Other Embodiments" section.

[0025] The phase difference between the first clutch member 11 and the second clutch member 12 when the dog clutch 10 is in a disengaged state and the input shaft 3 and the output shaft 4 are rotating at different rotational speeds, i.e., the phase difference between the input shaft 3 and the output shaft 4, is referred to as the "clutch phase difference." In this specification, "phase difference" refers to the clutch phase difference. The phase difference sensor 6 detects the phase θ1 of the first clutch member 11 and the phase θ2 of the second clutch member 12. The clutch phase difference can be calculated based on the detection value of the phase difference sensor 6.

[0026] Hereinafter, the rotation speed of the input shaft 3 will be referred to as the "input shaft rotation speed," and the rotation speed of the output shaft 4 will be referred to as the "output shaft rotation speed." The difference between the output shaft rotation speed and the input shaft rotation speed will be referred to as the "input / output shaft rotation speed difference." In this embodiment, the value obtained by subtracting the input shaft rotation speed from the output shaft rotation speed is defined as the input / output shaft rotation speed difference, and the positive or negative value of this value is indicated. However, in other embodiments, the value obtained by subtracting the output shaft rotation speed from the input shaft rotation speed may be defined as the input / output shaft rotation speed difference.

[0027] The control device 7 controls the input / output shaft rotation speed difference. In this embodiment, the control device 7 basically does not change the output shaft rotation speed, but changes the input shaft rotation speed by controlling the rotation of the rear wheel MG 82. The control device 7 performs a "synchronization operation" to reduce the absolute value of the input / output shaft rotation speed difference to reach the target rotation speed difference by issuing an engagement command to engage the dog clutch 10, which is in a released state. In addition, the "time when the clutch phase difference becomes such that the dog clutch 10 can be engaged" is defined as the "engagement time." The control device 7 outputs a drive command to the clutch actuator 5 to engage the dog clutch 10 at the engagement time.

[0028] The clutch engagement operation when switching from 2WD to 4WD will be described with reference to Figures 3 and 4. In Figure 3, the symbols "τ0 to τ5" are used to indicate time, and the changes in input / output shaft rotation speed and ACT stroke are shown. During period I from time τ0 to τ1, the control device 7 receives a switching command and determines the start of the switching operation. The command to switch from 2WD to 4WD generates an "engagement command to engage the dog clutch in a released state."

[0029] The input shaft rotation speed Nin before time τ1 is 0, and the output shaft rotation speed Nout is a positive value corresponding to the axle rotation speed proportional to the vehicle speed. Therefore, the input / output shaft rotation speed difference ΔN is a positive value. Here, the rotation speeds Nin, Nout, and rotation speed difference ΔN are expressed in units of [rpm], for example. However, as will be described later, in relation to expressing the target rotation speed differences ωs, -ωs in units of the phase difference change rate [deg / sec], "ω" is used as the symbol for the input / output shaft rotation speed difference together with "ΔN". Hereinafter, "input / output shaft rotation speed difference" will be appropriately abbreviated and referred to as "rotation speed difference".

[0030] During periods I and II, the dog clutch 10 is in the released state shown in Figure 4, and the engagement teeth 13, 14 are separated from each other. In response to the engagement command, the control device 7 drives the rear wheel MG 82 during period II from time τ1 to τ2, and increases the input shaft rotation speed Nin toward the output shaft rotation speed Nout so as to synchronize the rotation of the input shaft 3 with the rotation of the output shaft 4. This operation is the "synchronization operation."

[0031] Regarding the rotation mode of the dog clutch 10 during synchronization, the rotation mode in which the output shaft rotation speed Nout is greater than the input shaft rotation speed Nin is defined as the "positive rotation mode," and the rotation mode in which the output shaft rotation speed Nout is smaller than the input shaft rotation speed Nin is defined as the "negative rotation mode." The positive rotation mode is always in effect at the beginning of period II. The solid line indicates operation in which the positive rotation mode continues until the clutch is engaged. On the other hand, the two-dot chain line indicates operation in which the positive rotation mode switches to the negative rotation mode during synchronization.

[0032] If the forward rotation mode continues through the synchronization operation, the control device 7 controls the rotation speed difference ω so that the absolute value of the positive rotation speed difference ω decreases and reaches the positive target rotation speed difference ωs. The target rotation speed difference ωs is set so that the engagement shock falls within an acceptable range. When the positive rotation speed difference ω reaches the target rotation speed difference ωs at time τ2, the control device 7 outputs a drive command to the clutch actuator 5.

[0033] On the other hand, when switching from positive rotation mode to negative rotation mode during synchronization operation, the control device 7 controls the input shaft rotation speed Nin to be greater than the output shaft rotation speed Nout, thereby reducing the absolute value of the rotation speed difference ω that has turned from positive to negative until it reaches the negative rotation speed difference -ωs. When the negative rotation speed difference ω reaches the negative target rotation speed difference -ωs at time τ2, the control device 7 outputs a drive command to the clutch actuator 5.

[0034] During period III from time τ2 to time τ3, the ACT stroke changes from 0 to the standby stroke Stsb, and the dog clutch 10 transitions from the released state shown in Fig. 4 to the standby position. At the standby position, the top surfaces of the first engagement tooth 13 and the second engagement tooth 14 come into contact with each other, leaving no gap.

[0035] During period IV from time τ3 to τ4, phase alignment is performed between the first clutch member 11 and the second clutch member 12. Once phase alignment is complete and engagement is possible, the ACT stroke changes from the standby stroke Stsb to the full stroke Stfl during period V from time τ4 to τ5, and the dog clutch 10 transitions from the standby position in Figure 4 to the fully engaged state. The sum of periods III, IV, and V constitutes the clutch operation period.

[0036] In the conventional technology of Patent Document 1 (JP 2021-025561 A), future engagement times are predicted approximately from past engagement times, which increases the error with actual operation and lengthens the time required for phase alignment. The time required for phase alignment becomes dominant in the clutch operation time, reducing responsiveness to engagement commands. Therefore, this embodiment aims to improve the responsiveness of clutch engagement by appropriately controlling the difference in input / output shaft speed. This achieves highly responsive switching from 2WD to 4WD via clutch engagement.

[0037] The configuration of the dog clutch engagement control system of this embodiment will be described with reference to Figures 5 to 9. In Figure 5 and subsequent figures, attention will be focused only on clutch engagement on the rear wheel 92 side of the vehicle 90, and the rear wheel MG 82 will be simply referred to as "MG82".

[0038] The control device 7 switches between engagement and release of the dog clutch 10 in response to an external engagement command or release command. The control device 7 acquires the phases θ1 and θ2 of the first and second clutch members 11 and 12, the input shaft rotation speed Nin, and the output shaft rotation speed Nout from the phase difference sensor 6. The control device 7 controls the rotation of the MG 82 based on the acquired information, and outputs an ACT drive command to the clutch actuator 5.

[0039] When the control device 7 receives an engagement command to engage the released dog clutch 10, it rotates the MG 82 and starts a synchronization operation. In practice, the drive of the MG 82 is performed by a functional link between an MG speed control unit in the control device 7 and a separate MG control device. The MG control device controls the power supply from the power source to the MG 82 by operating the inverter, with the aim of mainly controlling the drive during the power regeneration operation of the rear wheels 92 after the clutch is engaged. Meanwhile, the MG speed control unit in the control device 7 exclusively controls the input shaft speed Nin during the synchronization operation before the clutch is engaged. In other words, part of the function of driving the MG 82 that performs the synchronization operation is executed by the control device 7 of the dog clutch engagement control system 100.

[0040] Regarding the driving of the clutch actuator 5, the control device 7 drives the clutch actuator 5 in the forward direction in two stages in response to an engagement command. First, the control device 7 moves the clutch actuator 5 to a standby stroke Stsb (see FIG. 3) position where the top surfaces of the first engagement teeth 13 and the second engagement teeth 14 are in contact with each other. Thereafter, when the clutch phase difference reaches the engagement phase difference, the control device 7 moves the clutch actuator 5 to a full stroke Stfl position, thereby engaging the dog clutch 10. Then, in response to a release command, the control device 7 drives the clutch actuator 5 in the reverse direction, thereby disengaging the dog clutch 10.

[0041] The phase difference sensor 6 includes a first phase detection unit 61 that detects the phase θ1 of the first clutch member 11, and a second phase detection unit 62 that detects the phase θ2 of the second clutch member 12. In the configuration example shown in Figure 5, the control device 7 calculates the clutch phase difference Δθ (= θ2 - θ1) based on the phases θ1 and θ2 output by the phase difference sensor 6. In other configuration examples, the clutch phase difference Δθ may be calculated inside the phase difference sensor 6 and output to the control device 7.

[0042] With reference to FIG. 6, the definition of the clutch phase difference Δθ in this embodiment will be described. Note that a different definition of the clutch phase difference will be described in the "Other Embodiments" section. As shown in the upper diagram, a state in which the rotational phases of the first engagement teeth 13 and the second engagement teeth 14 match is defined as a state in which "clutch phase difference Δθ = 0." In this state, the first clutch member 11 and the second clutch member 12 cannot be engaged. The pitch angle P is the angle obtained by dividing the angle of one rotation of the first clutch member 11 and the second clutch member 12 (i.e., 360 degrees) by the number of teeth. In this embodiment, the number of teeth of the first engagement teeth 13 and the second engagement teeth 14 is 36, and the pitch angle P is 10 degrees.

[0043] When the rotation of the second clutch member 12 is leading the rotation of the first clutch member 11, the clutch phase difference is "Δθ>0". On the other hand, when the rotation of the second clutch member 12 is lagging the rotation of the first clutch member 11, the clutch phase difference Δθ is "Δθ<0". With respect to the pitch angle P, the clutch phase difference Δθ is defined in the range of "-(1 / 2)P≦Δθ≦(1 / 2)P". In the example where the pitch angle P is 10 degrees, the range of the clutch phase difference Δθ is "-5 degrees≦Δθ≦5 degrees". As shown in the lower diagram, when the clutch phase difference Δθ=±(1 / 2)P (=±5 degrees), the first clutch member 11 and the second clutch member 12 can be engaged. The clutch phase difference at this time is called the "engagement phase difference".

[0044] FIG. 7 shows waveforms of the phases θ1 and θ2 of the first clutch member 11 and the second clutch member 12 detected by the phase difference sensor 6. The first phase detection unit 61 and the second phase detection unit 62 of the phase difference sensor 6 detect the edges (shown by thick lines) of the first engagement tooth 13 and the second engagement tooth 14, respectively, and output pulse waveforms. The output pulse period T1 of the first phase detection unit 61 is proportional to the input shaft rotation speed Nin. The output pulse period T2 of the second phase detection unit 62 is proportional to the output shaft rotation speed Nout. In this way, the phase difference sensor 6 of this embodiment also functions as a rotation speed sensor for the input shaft 3 and the output shaft 4. Note that the control device 7 may acquire sensor values ​​from the rotation speed sensor, wheel speed sensor, etc. of the MG82 and refer to the rotational speed value converted using the reduction ratio.

[0045] Furthermore, the time difference ΔT between the output pulse edge of the first phase detector 61 and the output pulse edge of the second phase detector 62 is proportional to the clutch phase difference Δθ. For example, when the output pulse period T2 of the second phase detector 62 is used as a reference, the clutch phase difference Δθ is calculated by equation (1).

[0046] Δθ[deg]=P[deg]×(ΔT / T2) ···(1)

[0047] As shown in the upper part of FIG. 8, the configuration of the phase difference sensor 6 of this embodiment can detect the clutch phase difference Δθ at the timing of each pulse edge detection of the reference shaft (the input shaft in this embodiment), allowing for continuous detection. In the configuration used in Patent Document 1 as a comparative example to this embodiment, the total area of ​​both engaging teeth 13, 14 within a detection range set at the boundary between the first clutch member 11 and the second clutch member 12 is detected, and a beat waveform is output. As shown in the lower part of FIG. 8, the configuration of the comparative example can detect the clutch phase difference Δθ only at the engagement timing corresponding to the node of the beat wave, resulting in discontinuous detection. Therefore, the configuration of the comparative example cannot obtain information on the clutch phase difference Δθ at the timing required for control in this embodiment.

[0048] Next, referring to Figure 9, we will explain the selection of forward rotation mode or negative rotation mode according to the clutch phase difference Δθ. When the clutch phase difference Δθ is "0 < Δθ < (1 / 2)P", rotation in forward rotation mode where "output shaft rotation speed Nout > input shaft rotation speed Nin" reaches the engagement time earlier than rotation in negative rotation mode. Therefore, if rotation is currently in forward rotation mode, highly responsive clutch engagement can be achieved by continuing to operate in forward rotation mode.

[0049] On the other hand, when the clutch phase difference Δθ is "-(1 / 2)P<Δθ<0," rotation in negative rotation mode, where "output shaft rotation speed Nout < input shaft rotation speed Nin," reaches the engagement time earlier than rotation in positive rotation mode. Therefore, if the clutch is currently rotating in positive rotation mode, high-response clutch engagement can be achieved by increasing the input shaft rotation speed Nin and switching to negative rotation mode.

[0050] Here, the rotation mode with a shorter arrival time until the engagement time is referred to as the "early rotation mode." The process of determining whether the forward rotation mode or the negative rotation mode is the early rotation mode is referred to as the "early determination." The control device 7 of this embodiment performs the early determination based on the clutch phase difference Δθ detected during or after the synchronization operation is completed. When the current rotation mode differs from the early rotation mode, the control device 7 controls the input / output shaft rotation speed difference to switch from the current rotation mode to the early rotation mode. This shortens the time until clutch engagement and improves responsiveness.

[0051] Next, the clutch engagement control of the first to fourth embodiments will be described with reference to time charts, flowcharts, and diagrams illustrating the phase change calculation method in the second and third embodiments. The time charts show the rotation speed difference, clutch phase difference, and ACT stroke.

[0052] The rotation speed difference (difference in rotation speed between input and output shafts) is converted from rotation speed units [rpm] to phase difference change speed units [deg / sec]. More specifically, the rotation speed difference ΔN (= Nout - Nin) [rpm] is converted to ω [deg / sec] using equation (2).

[0053] ω[deg / sec] =ΔN[rpm]×360[deg]÷60[sec] ···(2)

[0054] At the start of the synchronization operation, it is assumed that the output shaft rotation speed Nout is greater than the input shaft rotation speed Nin, so the rotation speed difference ω0 at the start of the synchronization operation is a positive value. During the synchronization operation, the dog clutch 10 rotates in the forward rotation mode, and the rotation speed difference ω decreases at a predetermined gradient a0 from the initial value ω0 toward the positive target rotation speed difference ωs. If the rotation mode is switched to the negative rotation mode as a result of the early arrival determination, the rotation speed difference ω reaches the negative target rotation speed difference (-ωs).

[0055] The target rotation speed differences ωs and -ωs are set to values ​​that allow the engagement shock from the positive rotation mode and the engagement shock from the negative rotation mode to fall within the allowable range, respectively. Here, the absolute values ​​of the positive target rotation speed difference ωs and the negative target rotation speed difference (-ωs) do not have to be the same. In each time chart and explanatory diagram of the phase change amount calculation method, the absolute value of the negative target rotation speed difference (-ωs) is shown to be larger than the positive target rotation speed difference ωs.

[0056] The clutch phase difference Δθ is expressed in the range of "-5° to +5°" for the clutch configuration with 36 teeth shown in Figure 6. In reality, many cycles of sawtooth waveforms appear during synchronization operation, but only two cycles are shown in the figure. Furthermore, while the rotation speed difference ω changes, the hypotenuse of the sawtooth waveform is strictly speaking a curved line, but for convenience it is shown as a straight line.

[0057] In each embodiment, the rotation speed difference ω and clutch phase difference Δθ after the phase difference detection timing td are shown with a solid line for the early rotation mode out of the forward rotation mode and the negative rotation mode with a dashed line for the non-early rotation mode. The clutch engagement timing in the forward rotation mode is denoted as teP, and the clutch engagement timing in the negative rotation mode is denoted as teN. The diagram for the case where the early rotation mode is the forward rotation mode is exemplified only in FIG. 10 of the first embodiment. The other time charts show diagrams for the case where the early rotation mode is the negative rotation mode.

[0058] The ACT stroke diagram corresponds to Figure 3. In order to perform the clutch engagement operation, the engagement time must arrive after the ACT stroke reaches the standby stroke Stsb. In other words, the synchronization operation must be completed so that the ACT stroke reaches the standby stroke Stsb before the engagement time teP or teN in the early rotation mode, and the clutch actuator 5 must start operating.

[0059] In the explanation of the flowcharts, the symbol "S" means a step. The horizontal axis of the time chart shows part of the corresponding step number. The same step number in each flowchart corresponds to a substantially common step. Because common step numbers are used, the step numbers in each flowchart are not necessarily consecutive and include missing numbers. S1, S7Y, S7N, and S10 are common to the first to fourth embodiments.

[0060] S8 in the first and second embodiments and S2 in the third and fourth embodiments are all steps for determining whether the synchronization operation is complete, and the step numbers are differentiated based on the order of execution relative to the early arrival determination step. Similarly, S9 in the first and second embodiments, S3 in the third embodiment, and S3A in the fourth embodiment are all steps for operating the clutch actuator, and the step numbers are differentiated based on the order of execution relative to the early arrival determination step.

[0061] S41 is a clutch phase difference detection step corresponding to the first and second embodiments, S43 is a clutch phase difference detection step corresponding to the third embodiment, and S44 is a clutch phase difference detection step corresponding to the fourth embodiment. S61 is a clutch phase difference detection step corresponding to the first embodiment, S62 is a clutch phase difference detection step corresponding to the second and third embodiments, and S64 is a clutch phase difference detection step corresponding to the fourth embodiment. S3B is a clutch phase difference detection step corresponding to the fourth embodiment, ... first embodiment, S62 is a clutch phase difference detection step corresponding to the second and third embodiments, and S64 is a clutch phase difference detection step corresponding to the fourth embodiment.

[0062] In the second and third embodiments, in order to predict the clutch phase difference after the advance time Tdf has elapsed from the phase difference detection timing td, the phase difference change amount is calculated by calculating the area of ​​"time x rotation speed difference." The area calculation method is shown in each explanatory diagram.

[0063] (First embodiment) Clutch engagement control according to the first embodiment will be described with reference to Figures 10 to 12. In the first embodiment, the control device 7 makes an early engagement determination based on the clutch phase difference at the timing when the clutch phase difference is detected during the synchronization operation. Since the early engagement determination is made based on the clutch phase difference information at an early stage during the synchronization operation, clutch engagement with high response is possible.

[0064] Figure 10 shows a time chart when the early rotation mode is the forward rotation mode, and Figure 11 shows a time chart when the early rotation mode is the reverse rotation mode. In both cases, the rotation speed difference ω decreases toward the positive target rotation speed difference ωs in the forward rotation mode during synchronization. The clutch phase difference Δθd is detected at timing td before time ts when the rotation speed difference ω reaches the target rotation speed difference ωs (i.e., during synchronization).

[0065] During synchronization, as indicated by the dashed circle, the clutch phase difference Δθd is detected and repeatedly updated at multiple times according to the calculation cycle of the control device 7. If the detection timing td of the clutch phase difference Δθd is too early, the accuracy of the early arrival determination may be low. Therefore, it is preferable to use the clutch phase difference Δθd detected at the timing td immediately before the target rotational speed difference reaching time ts, out of the repeatedly updated clutch phase difference Δθd.

[0066] The detected clutch phase difference Δθd is compared with a threshold value Δθth. In the example of Figure 10, the clutch phase difference Δθd at the phase difference detection timing td is equal to or greater than the threshold value Δθth. In this case, if the forward rotation mode continues, the rotation speed difference ω is maintained at the positive target rotation speed difference ωs after the target rotation speed difference arrival time ts. The clutch phase difference Δθ increases at a constant rate toward the engagement phase difference of +5 degrees. This allows the clutch to be engaged at an engagement time teP that is earlier than the engagement time teN when switching to the negative rotation mode.

[0067] On the other hand, in the example of Figure 11, the clutch phase difference Δθd at the phase difference detection timing td is smaller than the threshold value Δθth. In this case, when the mode is switched to the negative rotation mode, the rotation speed difference ω decreases to the negative target rotation speed difference -ωs after the target rotation speed difference arrival time ts. The clutch phase difference Δθ decreases in positive slope and passes a maximum point when the rotation speed difference ω is 0. Then, it changes to a negative slope and approaches the engagement phase difference of -5 degrees. This allows the clutch to be engaged at engagement time teN, which is earlier than engagement time teP if the forward rotation mode is continued.

[0068] If it is assumed that the gradient of the clutch phase difference Δθ changes instantaneously when determining whether to switch from the positive rotation mode to the negative rotation mode, the threshold value Δθth is considered to be 0°. However, in reality, there is a time lag due to the transition time from the positive target rotation speed difference ωs to the negative target rotation speed difference −ωs and the operational response time of the MG82 for increasing the input shaft rotation speed Nin. Therefore, it is preferable to set the threshold value Δθth to a value slightly smaller than 0°, for example, -2 to -1°.

[0069] The flowchart in Figure 12 shows the clutch engagement control process according to the first embodiment. This process starts when an engagement command is input. In S1, synchronization of the input and output shafts is initiated, and the absolute value of the rotational speed difference |ω| gradually decreases at a slope a0. In S41, the control device 7 detects the clutch phase difference Δθ at timing td during the synchronization process.

[0070] In S61 for determining whether the clutch is fast, the clutch phase difference Δθd at the phase difference detection timing td is compared with a threshold value Δθth. If "Δθd≧Δθth", the fast rotation mode is determined to be a positive rotation mode in S7Y. If "Δθd<Δθth", the fast rotation mode is determined to be a negative rotation mode in S7N. In the determination of "Δθd≧Δθth?", "≧" may be replaced with ">".

[0071] When the current rotation mode is the quick-arrange rotation mode, the control device 7 continues the current rotation mode. When the current rotation mode is different from the quick-arrange rotation mode, the control device 7 switches from the current rotation mode to the quick-arrange rotation mode.

[0072] In S8, it is determined whether the synchronization operation has been completed. That is, in the positive rotation mode, it is determined whether the positive rotation speed difference ω has reached the target rotation speed difference ωs or less, and in the negative rotation mode, it is determined whether the negative rotation speed difference ω has reached the target rotation speed difference −ωs or more. If the determination in S8 is YES, the clutch actuator 5 starts operating in S9. In S10, the clutch is engaged at the earlier of the engagement timing teP or teN.

[0073] (Second embodiment) Clutch engagement control according to the second embodiment will be described with reference to Figures 13 to 15. In the second embodiment, the control device 7 predicts the clutch phase difference after a predetermined progression time has elapsed from the timing at which the clutch phase difference is detected during synchronization operation, and performs early engagement determination. Here, "progression time" means the time during which the clutch rotation progresses. Since early engagement determination is performed based on clutch phase difference information at an early stage during synchronization operation, clutch engagement can be performed with high response.

[0074] The time chart in Figure 13 differs from Figure 11 of the first embodiment only in that a predicted time tf after the progression time Tdf has elapsed since the phase difference detection time td is added. During synchronization, the rotation speed difference ω decreases toward the positive target rotation speed difference ωs in the forward rotation mode. The clutch phase difference Δθd is detected at time td before the rotation speed difference ω reaches the target rotation speed difference ωs (i.e., during synchronization).

[0075] When the positive rotation mode is continued from the phase difference detection timing td, the rotation speed difference ω reaches the positive target rotation speed difference ωs and is maintained thereafter. When switching to the negative rotation mode, the rotation speed difference ω decreases to the negative target rotation speed difference -ωs and is maintained thereafter. When the positive rotation mode is continued and when switching to the negative rotation mode, the clutch phase differences Δθp and Δθn are predicted at the prediction time tf after the advance time Tdf has elapsed from the phase difference detection timing td.

[0076] In the flowchart of Fig. 14, S5 and S62 are executed instead of S61 in Fig. 12. In S5, the control device 7 predicts the clutch phase difference Δθp in the forward rotation mode and the clutch phase difference Δθn in the negative rotation mode at a prediction time tf after the lapse of the advance time Tdf from the phase difference detection timing td.

[0077] In S62, which determines whether the clutch phase differences Δθp and (-Δθn) at the prediction time tf are large or small, the rotation mode corresponding to the smaller clutch phase difference is determined to be the early-arrival rotation mode. If "Δθp ≧ (-Δθn)", S7Y determines that the early-arrival rotation mode is the positive rotation mode. If "Δθp < (-Δθn)", S7N determines that the early-arrival rotation mode is the negative rotation mode. Note that "≧" in the determination of "Δθp ≧ (-Δθn)?" may be replaced with ">". Depending on whether the current rotation mode is the early-arrival rotation mode, the control device 7 either continues the current rotation mode or switches to the early-arrival rotation mode. S8-S10 are the same as those in the first embodiment (FIG. 12).

[0078] Fig. 15 shows a method for calculating the amount of phase change from the clutch phase difference detection timing td to the predicted time tf in the second embodiment. The amount of phase change is calculated as the area of ​​a figure on a coordinate system where the horizontal axis is time [sec] and the vertical axis is the rotation speed difference [deg / sec]. Here, the following symbols are defined:

[0079] ωd: Rotation speed difference at phase difference detection timing td ts: Time when the rotation speed difference ω reaches the target rotation speed difference ωs Tds: Time from the phase difference detection timing td to the target rotation speed difference arrival time ts Tsf: Time from the target rotation speed difference arrival time ts to the predicted time tf Txp: The time it takes for the rotation speed difference ω to decrease from the positive target rotation speed difference ωs to 0 Txn: Time required for the rotation speed difference ω to decrease from 0 to the negative target rotation speed difference ωs

[0080] The amount of phase change in positive rotation mode is calculated using the total area C of the area of ​​the right triangle Ca and the area of ​​the rectangle Cb. The equations for Ca and Cb are shown in the figure. In the equations for Ca and Cb, Tds can be eliminated by using the decreasing gradient a0 of the rotation speed difference ω (= (ωd - ωs) / Tds). The amount of phase change in negative rotation mode is calculated using the area D obtained by subtracting the area Dn of the trapezoid from the area Dp of the right triangle. The equations for Dp and Dn are shown in the figure.

[0081] (Third embodiment) Referring to Figures 16 to 18, clutch engagement control according to the third embodiment will be described. In the third embodiment, the control device 7 predicts the clutch phase difference after a predetermined progression time has elapsed from the timing at which the clutch phase difference is detected after the synchronization operation is completed, and performs an early engagement determination. As in the second embodiment, the "progression time" refers to the time during which the clutch rotation progresses. Since the early engagement determination is performed based on accurate clutch phase difference information after the synchronization operation is completed, highly responsive and accurate clutch engagement is possible.

[0082] As shown in the time chart of Figure 16, the rotation speed difference ω decreases in the forward rotation mode and reaches 0 after the rotation speed difference ωs has passed the positive target rotation speed difference ωs "after the synchronization operation is completed." The clutch phase difference Δθd is detected at timing td after the rotation speed difference ω reaches 0. Note that in the third embodiment, unlike the fourth embodiment described below, the ACT stroke has not reached the standby stroke Stsb (see Figure 3) at the phase difference detection timing td.

[0083] When the positive rotation mode is continued from the phase difference detection timing td, the rotation speed difference ω increases from 0 to the positive target rotation speed difference ωs and is then maintained. When switching to the negative rotation mode, the rotation speed difference ω decreases from 0 to the negative target rotation speed difference -ωs and is then maintained. When continuing the positive rotation mode and when switching to the negative rotation mode, the clutch phase differences Δθp and Δθn are predicted at the prediction time tf after the advance time Tdf has elapsed from the phase difference detection timing td.

[0084] In the flowchart of Figure 17, S2 and S3 are executed after S1. If it is determined in S2 that the positive rotation speed difference ω is equal to or less than the target rotation speed difference ωs, or if the negative rotation speed difference ω is equal to or greater than the target rotation speed difference -ωs, the clutch actuator 5 starts operating in S3. In S43, the control device 7 detects the clutch phase difference Δθd after the synchronization operation is completed. The prediction in S5 and the early arrival determination in S62 are the same as those in the second embodiment (Figure 14).

[0085] Depending on whether the current rotation mode is the early rotation mode determined in S7Y or S7N, the control device 7 continues the current rotation mode or switches to the early rotation mode. In S10, the clutch is engaged at the earlier of the engagement timings teP or teN.

[0086] Fig. 18 shows a method for calculating the phase change amount from the clutch phase difference detection timing td to the prediction time tf in the third embodiment. The phase change amount in the positive rotation mode is calculated using the area E of the trapezoid. The phase change amount in the negative rotation mode is calculated using -(area F of the trapezoid). The formulas for E and F are shown in the figure.

[0087] (Modification of the third embodiment) A modified example of the third embodiment will be described with reference to Figures 19 and 20. As shown in the time chart of Figure 19, in this modified example, when the rotation speed difference ω decreases in the forward rotation mode to reach the positive target rotation speed difference ωs and the synchronization operation is completed, the clutch phase difference Δθd is detected at timing td with the target rotation speed difference ωs maintained.

[0088] If the forward rotation mode is continued from the phase difference detection timing td, the rotation speed difference ω is maintained as the target rotation speed difference ωs. If the mode is switched to the negative rotation mode, the rotation speed difference ω decreases from the positive target rotation speed difference 0 to the negative target rotation speed difference -ωs. When the forward rotation mode is continued and when the mode is switched to the negative rotation mode, the clutch phase differences Δθp and Δθn are predicted at the prediction time tf after the advance time Tdf has elapsed from the phase difference detection timing td.

[0089] If the relationship between the clutch phase difference Δθp in the positive rotation mode and the clutch phase difference Δθn in the negative rotation mode at the predicted time tf is "Δθp<-(Δθn)" as shown in Figure 19, it is determined that the negative rotation mode is the early rotation mode.

[0090] Fig. 20 shows a method for calculating the phase change amount from the clutch phase difference detection timing td to the prediction time tf in a modified example of the third embodiment. The phase change amount in the positive rotation mode is calculated using the area G of a rectangle. The phase change amount in the negative rotation mode is calculated using the area H obtained by subtracting the area Hn of a trapezoid from the area Hp of a right triangle. The equations for the areas G, Hp, and Hn are shown in the figure.

[0091] (Fourth embodiment) Referring to Figures 21 and 22, clutch engagement control according to the fourth embodiment will be described. In the fourth embodiment, the control device 7 performs an early engagement determination based on the clutch phase difference at the timing when the clutch phase difference is detected after the synchronization operation is completed and the clutch actuator 5 is actuated and the top surfaces of the first engagement teeth 13 and the second engagement teeth 14 have reached a contact state. Since the early engagement determination is performed based on accurate clutch phase difference information after the synchronization operation is completed and the top surfaces have come into contact, it is possible to perform clutch engagement with high response and high accuracy. Furthermore, since prediction as in the second and third embodiments is not required, the calculation load can be reduced.

[0092] As shown in the time chart of Figure 21, when the rotation speed difference ω decreases in the forward rotation mode and reaches the positive target rotation speed difference ωs, the synchronization operation is completed and the clutch actuator 5 starts to operate. Then, the ACT stroke reaches the standby stroke Stsb (see Figure 3), that is, the clutch phase difference Δθd is detected at timing td after the top surfaces of the first engagement tooth 13 and the second engagement tooth 14 of the dog clutch 10 have come into contact with each other. Note that in order to accommodate variations in the standby stroke Stsb due to variations in product dimensions, etc., if the clutch phase difference Δθd is detected in a gray zone within the range of variation in the standby stroke Stsb, the early arrival determination may be redone.

[0093] The clutch phase difference Δθd detected at the phase difference detection timing td is compared with a threshold value Δθth to determine whether the clutch is in an early-arrival state. If the early-arrival rotation mode is determined to be a positive rotation mode, the rotation speed difference ω is maintained at the target rotation speed difference ωs. If the early-arrival rotation mode is determined to be a negative rotation mode, the mode is switched from the positive rotation mode to the negative rotation mode, and the rotation speed difference ω decreases from the positive target rotation speed difference ωs to the negative target rotation speed difference -ωs.

[0094] In the flowchart of Figure 22, after S1 and S2, S3A, S3B, and S44 are executed. If a YES determination is made in S2, the clutch actuator 5 starts operating in S3A. If a YES determination is made in S3B, it is determined whether the ACT stroke has reached the standby stroke Stsb. If a YES determination is made in S3B, the control device 7 detects the clutch phase difference Δθd after the synchronization operation is completed and the standby stroke Stsb has been reached in S44.

[0095] In S64, which is the early arrival determination, the clutch phase difference Δθd at the phase difference detection timing td is compared with a threshold value Δθth. If "Δθd ≥ Δθth", in S7Y, it is determined that the early arrival rotation mode is a positive rotation mode. If "Δθd < Δθth", in S7N, it is determined that the early arrival rotation mode is a negative rotation mode. In the determination of "Δθd ≥ Δθth?", "≥" may be replaced with ">". The threshold value Δθth does not have to be the same as the threshold used in S61 of the first embodiment, but may be set to approximately -2 to -1 degrees as in the first embodiment.

[0096] Depending on whether the current rotation mode is the early rotation mode determined in S7Y or S7N, the control device 7 continues the current rotation mode or switches to the early rotation mode. In S10, the clutch is engaged at the earlier of the engagement timings teP or teN.

[0097] (Other embodiments) 1, 5, etc. has a face-type gear configuration in which the clutch members 11, 12 themselves move relative to each other in the axial direction, allowing direct meshing between the first engagement teeth 13 of the first clutch member 11 and the second engagement teeth 14 of the second clutch member 12. In addition to this configuration, a sleeve-type clutch may be used in which the clutch members are stationary and a movable sleeve is provided as a separate part as an intermediary member.

[0098] A sleeve-type clutch is disclosed, for example, in Japanese Patent Application Laid-Open No. 2010-96190. In a sleeve-type clutch, first engagement teeth of a first clutch member and second engagement teeth of a second clutch member can mesh with each other via a sleeve serving as an intermediary member. A clutch actuator axially moves the sleeve relative to the first clutch member and the second clutch member, thereby switching the engaged and disengaged states of the dog clutch.

[0099] In the description of the fourth embodiment, the phrase "after the top surfaces of the first engagement tooth 13 and the second engagement tooth 14 reach a contact state" can be read as "after the first engagement tooth 13 and the second engagement tooth 14 reach an engagement boundary state via the relay member" if an intermediary member is used. The "engagement boundary state" is a boundary state between the released state and the engaged state, and is the state in which the clutch is in the standby position in FIG. 4. This clutch configuration also achieves the same effects as the fourth embodiment, and because early engagement determination is made based on accurate clutch phase difference information after the engagement boundary state is reached, highly responsive and accurate clutch engagement is possible.

[0100] (b) The dog clutch 10 is not limited to being arranged between the rear wheel MG 82 and the rear wheels 92 in the 2WD / 4WD switchable vehicle 90 illustrated in Figure 1, but may also be arranged, for example, between the front wheel MG and the front wheels in a front-wheel drive (FF) vehicle.

[0101] (c) The clutch phase difference may be defined as 0 degrees when the first clutch member 11 and the second clutch member 12 are in an engageable state. In this case, the phase difference of the dog clutch 10 having 36 teeth varies within the range of 0 to +10 degrees.

[0102] (d) The rotary drive source connected to the input shaft 3 is not limited to the MG82, but may be an internal combustion engine, etc. Furthermore, the dog clutch engagement control system may be applied to power transmission mechanisms of general machinery in addition to vehicle powertrains.

[0103] (e) Depending on the usage conditions of the applied system, when switching from the positive rotation mode to the negative rotation mode, the input shaft rotation speed Nin may be increased without changing the output shaft rotation speed Nout, or the output shaft rotation speed Nout may be decreased without changing the input shaft rotation speed Nin. Alternatively, both the input shaft rotation speed Nin may be increased and the output shaft rotation speed Nout may be decreased, or either may be selected depending on the conditions.

[0104] The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the invention.

[0105] The control device and methods described herein may be implemented by a special-purpose computer configured with a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control device and methods described herein may be implemented by a special-purpose computer configured with a processor comprising one or more dedicated hardware logic circuits. Alternatively, the control device and methods described herein may be implemented by one or more special-purpose computers configured with a processor and memory programmed to perform one or more functions in combination with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored in a computer-readable non-transitory tangible storage medium as instructions executed by a computer. [Explanation of symbols]

[0106] 100... Dog clutch engagement control system, 10. Dog clutch, 11: First clutch member; 13: First engagement teeth; 12: Second clutch member; 14: Second engagement teeth; 3: Input shaft; 4: Output shaft; 5. Clutch actuator, 6 Phase difference sensor, 7. Control device.

Claims

1. a dog clutch (10) including a first clutch member (11) connected to an input shaft (3) and having a plurality of first engagement teeth (13) arranged in a circumferential direction, and a second clutch member (12) connected to an output shaft (4) and having a plurality of second engagement teeth (14) arranged in a circumferential direction and capable of engaging with the first engagement teeth directly or via an intermediate member, the dog clutch (10) switching between an engaged state and a released state of the first clutch member and the second clutch member; a clutch actuator (5) that moves the first clutch member and the second clutch member relative to each other in the axial direction, or, when the relay member is used, moves the relay member relative to the first clutch member and the second clutch member in the axial direction; a phase difference sensor (6) that detects the phase (θ1) of the first clutch member and the phase (θ2) of the second clutch member, and is capable of calculating a clutch phase difference, which is the phase difference between the first clutch member and the second clutch member, based on the detected values; a control device (7) that controls an input / output shaft rotational speed difference (ΔN, ω) that is the difference between the rotational speed (Nout) of the output shaft and the rotational speed (Nin) of the input shaft, and performs a synchronization operation to reduce the absolute value of the input / output shaft rotational speed difference to reach a target rotational speed difference (ωs, −ωs) by an engagement command to engage the dog clutch in a released state, and outputs a drive command to the clutch actuator to engage the dog clutch at an engagement timing that provides a clutch phase difference that allows the dog clutch to be engaged; Equipped with If a rotation mode in which the rotation speed of the output shaft is greater than the rotation speed of the input shaft is defined as a positive rotation mode, and a rotation mode in which the rotation speed of the output shaft is smaller than the rotation speed of the input shaft is defined as a negative rotation mode, then: The control device performing an early arrival determination based on the clutch phase difference detected during the synchronizing operation or after completion of the synchronizing operation, to determine whether the positive rotation mode or the negative rotation mode is an early arrival rotation mode having a shorter arrival time until the engagement time; a dog clutch engagement control system for controlling the input / output shaft rotation speed difference to switch from the current rotation mode to the early rotation mode when the current rotation mode is different from the early rotation mode;

2. 2. The dog clutch engagement control system according to claim 1, wherein the control device, at the timing when the clutch phase difference is detected during the synchronization operation, predicts the clutch phase difference after a predetermined progression time has elapsed from that timing and makes the early engagement judgment.

3. 2. The dog clutch engagement control system according to claim 1, wherein the control device, at the timing when the clutch phase difference is detected after the synchronization operation is completed, predicts the clutch phase difference after a predetermined progression time has elapsed from that timing and makes the early engagement judgment.

4. 2. The dog clutch engagement control system of claim 1, wherein the control device makes the early engagement judgment based on the clutch phase difference at the timing when the clutch phase difference is detected after the synchronization operation is completed and the clutch actuator is activated and the top surfaces of the first engagement tooth and the second engagement tooth reach a contact state, or when the relay member is used and the first engagement tooth and the second engagement tooth reach an engagement boundary state via the relay member.

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