Dog clutch engagement control system

Abstract

A clutch actuator (5) causes a first clutch member (11) and a second clutch member (12) of a dog clutch (10) to move relative to each other in the axial direction. A phase difference sensor (6) detects the phase difference between the first clutch member (11) and the second clutch member (12). A control device (7) performs a synchronization operation for gradually reducing the rotation speed difference between input and output shafts until the rotation speed difference reaches a target rotation speed difference (ωs), and detects the current engagement timing on the basis of the output of the phase difference sensor (6). After an adjustment reference time (t1) at which the rotation speed difference between the input and output shafts reaches a rotation speed difference (ω0) at which the phase difference can be detected by the phase difference sensor (6), the control device (7) adjusts the phase difference by changing the change characteristics of the rotation speed difference between the input and output shafts so that any future engagement timing matches a completion target time (tall), on the basis of information acquired at an arbitrary phase difference detection time (td).

Description

Dog clutch engagement control system CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2023-185557, filed on October 30, 2023, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a dog clutch engagement control system.

[0003] Conventionally, a dog clutch engagement control system has been known that engages an input shaft and an output shaft that rotate at different rotational speeds in a disengaged state. For example, Patent Document 1 discloses a technology for predicting future engagement times based on multiple past engagement times (engagement 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. The control device then pre-drives a clutch actuator so that the dog clutch engages at the predicted engagement time after the input / output shaft rotational speed difference reaches the target rotational speed difference.

[0004] Japanese Patent Application Laid-Open No. 2021-025561

[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 based on past engagement times, the error from actual operation increases. This increases the time required for phase alignment between when the input / output shaft rotational speed difference reaches the target rotational speed difference and when engagement is actually performed, reducing responsiveness to an engagement command.

[0006] An object of the present disclosure is to provide a dog clutch engagement control system that achieves highly accurate adjustment of the phase difference between the input and output shafts and improves the responsiveness of clutch engagement.

[0007] The dog clutch engagement control system of the present disclosure includes a dog clutch, a clutch actuator, a phase difference sensor, and a controller.

[0008] The dog clutch has a first clutch member and a second clutch member, and the first clutch member and the second clutch member are switched between an engaged state and a disengaged state. The first clutch member is connected to the input shaft and has a plurality of first engagement teeth arranged in the circumferential direction. The second clutch member is connected to the output shaft and has a plurality of second engagement teeth arranged in the circumferential direction, which can mesh with the first engagement teeth directly or via an intermediate member.

[0009] In a dog clutch engagement control system mounted on a vehicle, the input shaft is connected to a motor or an internal combustion engine via a reducer, for example, and 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. The phase difference sensor detects the phase difference between the first clutch member and the second clutch member.

[0011] The control device controls the input / output shaft rotation speed difference, which is the difference between the rotation speed of the input shaft and the rotation speed of the output shaft. The control device performs a synchronization operation by issuing an engagement command to engage the dog clutch that is in a released state, gradually reducing the input / output shaft rotation speed difference until it reaches a target rotation speed difference at which the dog clutch can be engaged.

[0012] In the synchronization operation, the control device detects the current engagement timing based on the output of the phase difference sensor for the engagement timing at which the dog clutch can be engaged, and outputs a drive command to the clutch actuator to engage the dog clutch at a future engagement timing after the input / output shaft rotational speed difference has reached the target rotational speed difference.

[0013] The control device adjusts the phase difference between the first clutch member and the second clutch member by changing the change characteristics of the input / output shaft rotational speed difference so that one of the future engagement times coincides with the target completion time, based on information acquired at an arbitrary phase difference detection time at which an arbitrary phase difference is detected based on the output of the phase difference sensor after the adjustment reference time. The adjustment reference time is the time at which the input / output shaft rotational speed difference reaches a rotational speed difference at which the phase difference can be detected by the phase difference sensor. The target completion time is the time after the target completion time from the adjustment reference time. The arbitrary phase difference detection time is, for example, the time at which the first engagement time is detected after the adjustment reference time.

[0014] The "change characteristics of the input / output shaft rotation speed difference" that is changed in the phase difference adjustment of the present disclosure is, for example, a "gradient" that is the time rate of change of the input / output shaft rotation speed difference, or a "target rotation speed difference." In the present disclosure, by having the control device change the change characteristics of the input / output shaft rotation speed difference during synchronization operation, it is possible to achieve high-precision phase difference adjustment and improve clutch engagement responsiveness.

[0015] Here, we assume a different control method in which the timing when the input / output shaft rotational speed difference reaches a target rotational speed difference during synchronization is defined as the arrival time, and the future engagement time is predicted and then moved closer to the arrival time. In this case, if torque is input to the input shaft in an attempt to move the engagement time closer to the arrival time, the input shaft rotational speed may change, causing the arrival time to shift, which could reduce the accuracy of the phase difference adjustment. In contrast, in the present disclosure, the change characteristics of the input / output shaft rotational speed difference and the phase difference adjustment are simultaneously performed based on information acquired at an arbitrary phase difference detection time, thereby achieving highly accurate phase difference adjustment. Furthermore, in the present disclosure, the future engagement time does not necessarily have to be predicted.

[0016] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is a diagram of an example of the configuration of a vehicle to which a dog clutch engagement control system is applied, Fig. 2 is a schematic diagram showing switching between 2WD and 4WD, Fig. 3 is a time chart showing the switching operation from 2WD to 4WD under the control of a comparative example and this embodiment, Fig. 4 is a schematic diagram showing the state transition of a dog clutch, Fig. 5 is a configuration diagram of the dog clutch engagement control system of this embodiment, Fig. 6 is a block diagram of a control device, Fig. 7 is a diagram explaining the detection principle of a phase difference sensor, Fig. 8 is a diagram showing a beat waveform of the phase difference sensor output, Fig. 9 is a time chart of a synchronization operation according to the first embodiment, Fig. 10 is a time chart of phase difference adjustment according to the first embodiment (after the adjustment reference time t1 in Fig. 9 ), Fig. 11 is a flowchart of clutch engagement control according to the first embodiment, and Fig. 12 is a time chart of phase difference adjustment according to the second embodiment, FIG. 13 is a time chart of phase difference adjustment according to the third embodiment, FIG. 14 is a time chart of phase difference adjustment according to the fourth embodiment, FIG. 15 is a time chart of phase difference adjustment according to the fifth embodiment, FIG. 16 is a time chart of phase difference adjustment according to the sixth embodiment, FIG. 17 is a time chart of phase difference adjustment according to the seventh embodiment, FIG. 18 is a provisional time chart of phase difference adjustment at the first phase difference detection time td1 in the eighth embodiment, FIG. 19 is a provisional time chart of phase difference adjustment at the second phase difference detection time td2 in the eighth embodiment, FIG. 20 is a final time chart of phase difference adjustment at the third phase difference detection time td3 in the eighth embodiment, and FIG. 21 is a flowchart of clutch engagement control according to the eighth embodiment.

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

[0018] 1 and 2, a configuration example of a vehicle 90 to which a dog clutch engagement control system is applied will be described. The 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. The 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 drive wheels in addition to the front wheels 91. Note 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 state and the engaged state. For example, 2WD with 1MG driving is selected on a flat road with a low load, and 4WD with 2MG driving is selected on a slope requiring high driving force. 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 MG 82 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 an 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 with the first clutch member 11 in the same direction. 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 the 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] When the input shaft 3 and the output shaft 4 are rotating at different rotation speeds with the dog clutch 10 in a disengaged state, the phase difference sensor 6 detects the phase difference between the first clutch member 11 and the second clutch member 12, i.e., the phase difference between the input shaft 3 and the output shaft 4, and outputs a phase difference sensor signal to the control device 7. The dog clutch engagement control system 100 of this embodiment is mounted on a vehicle 90 in which the output shaft 4 is connected to rear wheels 92, which are drive wheels.

[0026] Hereinafter, the "time when the phase difference allows engagement of the dog clutch 10" is defined as the "engagement time." The "engagement time" includes not only a single time when an engagement operation is actually performed, but also multiple times when engagement is possible but the clutch is not engaged. The control device 7 detects the current engagement time based on the phase difference sensor signal and outputs a drive command to the clutch actuator 5 according to the future engagement time. Specifically, the control device 7 starts the anticipatory operation of the clutch actuator 5 a predetermined anticipatory operation time before the future engagement time. The control device 7 also controls the input / output shaft rotation speed difference, which is the difference between the rotation speed of the input shaft 3 and the rotation speed of the output shaft 4, by controlling the rotation of the rear wheel MG 82. Hereinafter, the reference numerals for the "input shaft 3" and "output shaft 4" related to the rotation speeds will be omitted as appropriate.

[0027] A typical engagement operation when switching from 2WD to 4WD will be described with reference to Figures 3 and 4. Figure 3 shows changes in input / output shaft rotation speed and ACT stroke under the control of the comparative example and this embodiment. In order to distinguish from the symbols for time t1 and the like used in Figure 9 and other figures, the symbols "τ0 to τ5" are used for the times in Figure 3. The control of the comparative example and this embodiment differ in the length of period IV from time τ3 to τ4. During period I from time τ0 to τ1, the control device 7 receives a switching instruction and determines the start of the switching operation. The switching instruction from 2WD to 4WD generates an "engagement instruction to engage a dog clutch that is in a released state."

[0028] 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. The output shaft rotation speed Nout corresponds to the rotation speed of the axle proportional to the vehicle speed. The operation of matching the input shaft rotation speed Nin and the output shaft rotation speed Nout is called the "synchronization operation." During periods I and II, the dog clutch 10 is in the released state shown in FIG. 4, and the engagement teeth 13, 14 are separated from each other.

[0029] The target rotation speed N_tgt of the input shaft rotation speed Nin is set so that the difference ΔN between it and the output shaft rotation speed Nout is within the acceptable range of engagement shock. Engagement is performed when the input shaft rotation speed Nin reaches the target rotation speed N_tgt, the input / output shaft rotation speed difference ΔN becomes equal to or less than the target rotation speed difference ωs, the ACT stroke reaches the standby stroke Stsb, and the phase difference becomes such that engagement is possible (i.e., engagement timing). Hereinafter, the "input / output shaft rotation speed difference" will be omitted and referred to as the "rotation speed difference." The rotation speed difference is defined as 0 or a positive value. The symbol "ωs" will be described later in the explanation of Figures 9 and 10.

[0030] When the input shaft rotation speed Nin reaches the target rotation speed N_tgt at time τ2, a drive command is output to the clutch actuator 5. 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 Figure 4 to the standby position. At the standby position, for example, the top surfaces of the engaging teeth 13, 14 come into contact with each other, leaving no gap.

[0031] During period IV from time τ3 to τ4, phase alignment between the first clutch member 11 and the second clutch member 12 is performed. 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 shown in Figure 4 to the fully engaged state. The sum of periods III, IV, and V constitutes the clutch operation period.

[0032] In conventional technology that predicts future engagement times by approximating past engagement times, the error from actual operation increases, resulting in a longer phase alignment time. This phase alignment time becomes dominant in the clutch operation time, resulting in a decrease in responsiveness to engagement commands. Therefore, this embodiment aims to shorten the phase alignment time by controlling the phase difference adjustment. This achieves highly responsive switching from 2WD to 4WD by clutch engagement.

[0033] The configuration of the dog clutch engagement control system of this embodiment will be described with reference to Figures 5 to 8. 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 "MG 82." The rotation speed of the MG 82 is detected by a rotation speed sensor 23 such as a resolver, and converted into the rotation speed of the input shaft 3 by multiplying it by the reduction ratio of the reducer 88. In Figure 5, the converted input shaft rotation speed Nin is assumed to be input to the control device 7. Meanwhile, the rotation speed of the output shaft 4 is detected by a rotation speed sensor 24 such as a wheel speed sensor, and the converted output shaft rotation speed Nout is input.

[0034] The phase difference sensor 6 is composed of a magnetic detection element, such as a Hall element, and a magnet. The phase difference sensor 6 has a detection range SA (see FIG. 7 ) in the axial direction that straddles the first engagement teeth 13 and the second engagement teeth 14, and is disposed so as to face the clutch axis Z from the radial outside where it does not interfere with the dog clutch 10. The phase difference sensor 6 detects the total area of ​​the first engagement teeth 13 and the second engagement teeth 14 that pass through the detection range SA as the dog clutch 10 rotates, based on changes in magnetic flux intensity.

[0035] 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. For example, 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. In FIG. 7 , an example configuration with 36 teeth is assumed, and the range of the phase difference is shown as ±5 degrees. Note that definitions of the phase difference other than this definition will be described in the "Other Embodiments" section.

[0036] The top diagram in Figure 7 shows the general phase difference Δθ during rotation. The middle diagram shows a state where the rotational phases of the first engagement teeth 13 and the second engagement teeth 14 are the same, that is, "phase difference Δθ = 0." In this state, the first clutch member 11 and the second clutch member 12 cannot engage with each other. The detection range SA includes both the tooth portions of the first engagement teeth 13 and the second engagement teeth 14, and the sensor output is maximized when the total area is maximized. The detection range SA includes both the gap portions of the first engagement teeth 13 and the second engagement teeth 14, and the sensor output is minimized when the total area is minimized.

[0037] The lower diagram in Figure 7 shows a state in which the rotational phase between the first engagement teeth 13 and the second engagement teeth 14 is shifted by half the pitch angle P, resulting in a "phase difference Δθ = ±(½)P (= ±5 deg)." In this state, the first clutch member 11 and the second clutch member 12 are engageable. The detection range SA includes one tooth portion of the first engagement teeth 13 and the second engagement teeth 14 and the gap portion of the other, and the sensor output becomes an intermediate value at the timing when the total area becomes an intermediate value between the maximum and minimum values.

[0038] 5 , 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 phase difference sensor signal, the input shaft rotation speed Nin, and the output shaft rotation speed Nout, controls the rotation of the MG 82 based on this information, and outputs a drive command to the clutch actuator 5. When the control device 7 receives an engagement command to engage the dog clutch 10, which is in a released state, it rotates the MG 82 and starts a synchronization operation to increase the input shaft rotation speed Nin so that it approaches the output shaft rotation speed Nout.

[0039] 6, the control device 7 includes a phase difference detection unit 71, a rotation speed difference / gradient calculation unit 72, a current phase difference estimation unit 73, a rotation speed difference change characteristic calculation unit, an MG rotation speed calculation unit 75, an MG rotation speed control unit 76, an ACT drive determination unit 77, an operation delay time estimation unit 78, and a target completion time correction unit 79. The symbols Δθd, td, ac, ωsc, Tall, and Tpre in the figure will be described later in the explanation of FIGS. 9 and 10.

[0040] The phase difference detection unit 71 filters the output of the phase difference sensor 6 to remove fluctuation components in a predetermined frequency range. As shown in FIG. 8 , the filtered output of the phase difference sensor exhibits a beat waveform. The nodes of the beat waveform correspond to the phase difference (Δθ=±(½)P) at which the dog clutch 10 can be engaged. The phase difference detection unit 71 outputs the phase difference Δθd detected from the phase difference sensor output and the time td at which the phase difference Δθd was detected to the rotation speed difference change characteristic calculation unit 74.

[0041] The rotation speed difference / gradient calculation unit 72 calculates the rotation speed difference between the input shaft rotation speed Nin and the output shaft rotation speed Nout, and the gradient, which is the rate of change of the rotation speed difference over time. The gradient is the rate of change of the rotation speed difference over time and is calculated by dividing the rotation speed difference by the elapsed time. The target value of the gradient in the rotation speed difference control is set as the "target gradient." The current phase difference estimator 73 estimates the current phase difference from the integrated value of the rotation speed difference from a predetermined reference time to the present. When the estimated phase difference at each time is plotted, a sawtooth-like change is displayed, as shown in Figure 9 and subsequent figures. This makes it possible to predict the phase difference at any future time.

[0042] The rotation speed difference change characteristic calculation unit 74 calculates the target gradient ac or the target rotation speed difference ωsc as the change characteristic of the rotation speed difference to be changed by controlling the phase difference adjustment, based on information including the phase difference Δθd and the time td obtained from the phase difference detection unit 71. As the change characteristic of the rotation speed difference, the gradient is changed in the first to fourth embodiments, and the target rotation speed difference is changed in the seventh embodiment. In the fifth and sixth embodiments, both the gradient and the target rotation speed difference are changed. Details will be described later in the explanation of each embodiment.

[0043] The MG rotation speed calculation unit 75 calculates the current MG rotation speed based on the output of the rotation speed sensor 23 and notifies the MG rotation speed control unit 76. The MG rotation speed control unit 76 controls the rotation of the MG 82 so that the target gradient ac or the target rotation speed difference ωsc calculated by the rotation speed difference change characteristic calculation unit 74 is realized.

[0044] For convenience, FIG. 6 shows the MG rotation speed control unit 76 as part of the control unit 7, but in reality, the control unit 7 is made up of a control device for the dog clutch engagement control system 100 and another MG control device functionally linked together. The MG control device controls the power supply from the power source to the MG 82 by operating the inverter, mainly for the purpose of drive control during power regeneration operation of the rear wheels 92 after clutch engagement. In contrast, the MG rotation speed control unit 76 in FIG. 6 exclusively controls the input shaft rotation speed Nin during synchronization operation before clutch engagement. In other words, of all the functions of the MG control device, at least the part that performs synchronization operation corresponds to the MG rotation speed control unit 76.

[0045] In response to an engagement command, the ACT drive determination unit 77 drives the clutch actuator 5 in the forward direction in two stages. First, the ACT drive determination unit 77 moves the clutch actuator 5 to a standby position by the time of engagement. Next, when engagement is executed, the ACT drive determination unit 77 moves the clutch actuator 5 to a full stroke position and engages the dog clutch 10. In response to a release command, the ACT drive determination unit 77 drives the clutch actuator 5 in the reverse direction and releases the dog clutch 10.

[0046] The action delay time estimation unit 78 estimates the action delay time when a factor that delays the action of the clutch actuator 5 occurs. For example, the larger the time constant of the filter processing in the phase difference detection unit 71, the longer the delay in detecting the phase difference. Furthermore, the greater the calculation load on the CPU constituting the control device 7, the greater the processing delay and communication delay between CPUs via the CAN, etc. Furthermore, the operating speed may change depending on the temperature of the clutch actuator 5. The action delay time estimation unit 78 estimates the action delay time of the clutch actuator 5 from this information and adjusts the ACT precedence action time Tpre according to the action delay time. The adjusted ACT precedence action time Tpre is fed back to the ACT drive determination unit 77.

[0047] 9 and 10 , the target completion time Tall is the time from the adjustment reference time t1 to the target completion time tall at which engagement is executed. The control device 7 starts the advance operation of the clutch actuator 5 a predetermined advance operation time Tpre before the target completion time tall. In principle, the target completion time Tall is a predetermined value, but if a factor that delays the operation of the clutch actuator 5 occurs, the target completion time correction unit 79 corrects the target completion time Tall in accordance with the operation delay time, and outputs the corrected value to the rotational speed difference change characteristic calculation unit 74.

[0048] The above is a description of an example configuration of the control device 7 according to this embodiment. The control device 7 of this embodiment adjusts the phase difference by coordinating the change in the rotation speed difference during synchronization with the change in the phase difference, thereby shortening the time required for phase alignment (see FIG. 3) and improving the response of clutch engagement. Next, specific configurations for phase difference adjustment according to each embodiment will be described in order.

[0049] (First Embodiment) Phase difference adjustment according to the first embodiment will be described with reference to FIGS. 9 to 11. FIG. 9 shows, from the top row to the bottom row, the input / output shaft rotation speeds, the rotation speed difference, the phase difference, and the integrated phase difference for the entire synchronization operation period in which the input shaft rotation speed Nin increases from 0. FIG. 10 shows, from the top row to the bottom row, the rotation speed difference, the phase difference, the ACT drive command, and the ACT stroke for the period after the adjustment reference time t1. The time charts for the rotation speed difference and phase difference shown in the second and third rows of FIG. 9 and the first and second rows of FIG. 10 partially overlap, but the ranges of the time axes are different. FIG. 10 shows changes during phase difference adjustment in more detail than FIG. 9, and additional information is also provided.

[0050] 9 and 10, the solid lines indicate the control of the first embodiment, and the two-dot chain lines indicate the control of the comparative example in which phase difference adjustment is not performed. The hatched triangles indicate the engagement timing in the control of the first embodiment, and the dashed triangles indicate the engagement timing in the control of the comparative example. Engagement is performed at the target completion time tall in the first embodiment, and at time tz in the comparative example.

[0051] In the diagram of the input / output shaft rotation speed, the symbol for the rotation speed is N [rpm]. In the diagram of the rotation speed difference, the symbol for the rotation speed difference is ω [deg / sec] instead of ΔN to be consistent with the mathematical formula. The rotation speed difference ΔN [rpm] is converted to ω [deg / sec] using equation (1). Therefore, the rotation speed difference is treated as a quantity synonymous with the phase difference change rate (or angular velocity difference).

[0052] ω [deg / sec] = ΔN [rpm] × 360 [deg] ÷ 60 [sec] ... (1)

[0053] The symbols in Figure 3 are used in the diagram of input and output shaft rotation speeds. The output shaft rotation speed Nout is constant, and the input shaft rotation speed Nin increases from an initial value of 0 toward the output shaft rotation speed Nout. When the input shaft rotation speed Nin reaches the detectable rotation speed N_sen at time t1, it becomes possible for the phase difference sensor 6 to detect the phase difference. This time is referred to as the "adjustment reference time t1."

[0054] Furthermore, the target rotation speed N_tgt is set so that the rotation speed difference between the input shaft rotation speed Nout and the target rotation speed N_tgt is within the tolerance range for engagement shock. Engagement is performed at the timing after the input shaft rotation speed Nin reaches the target rotation speed N_tgt and the ACT stroke reaches the standby stroke Stsb (see FIG. 10). The time at which the input shaft rotation speed Nin reaches the target rotation speed N_tgt is time tt in the comparative example and time ts in the first embodiment.

[0055] When the output shaft rotation speed Nout is constant, the rotation speed difference diagram corresponds to the rotation speed diagram turned upside down. The difference between the detectable rotation speed N_sen and the output shaft rotation speed Nout corresponds to the "rotation speed difference ω0 at which a phase difference can be detected." The difference between the target rotation speed N_tgt and the output shaft rotation speed Nout corresponds to the "target rotation speed difference ωs at which the dog clutch 10 can be engaged." The control device 7 controls the rotation speed difference and performs a synchronization operation by issuing an engagement command to engage the dog clutch 10 in a released state, gradually reducing the rotation speed difference until it reaches the target rotation speed difference ωs.

[0056] In the phase difference diagram, when the number of teeth is 36, the phase difference Δθ varies within a range of ±5° centered around 0°. Strictly speaking, the hypotenuse of the sawtooth wave is curved, but for convenience it is shown as a straight line. In the phase difference diagram, the dashed line in the period before the adjustment reference time t1 indicates that the phase difference cannot be detected.

[0057] The time after the adjustment reference time t1 when an arbitrary phase difference is detected based on the output of the phase difference sensor 6 is defined as the "arbitrary phase difference detection time td." During synchronization, the control device 7 detects the current engagement timing based on the output of the phase difference sensor 6. The phase difference detected at the arbitrary phase difference detection time td is represented as Δθd, and the rotation speed difference at the phase difference detection time td is represented as ωd. If the arbitrary phase difference detection time td is the present, the engagement timings shown after time td indicate future engagement timings. The diagram of the change in phase difference after time td is interpreted as being drawn as a result. At time td, the control device 7 does not always need to predict future changes in the phase difference. Note that an example in which it is preferable to predict the future phase difference will be described later in the eighth embodiment.

[0058] In this example, the phase difference Δθd detected at the arbitrary phase difference detection time td is +5°, which corresponds to the "phase difference at which the dog clutch 10 can be engaged." In FIG. 7, the engageable phase difference is expressed as "Δθd = ±5°." However, if Δθd takes two values ​​in equation (4) described below, a single solution cannot be determined. Therefore, the domain of Δθd is set to "-5° < Δθd ≦ +5°," excluding -5°. Furthermore, the target phase difference Δθt at the time of engagement is basically +5°. Therefore, in this example, "Δθt - Δθd = 0." The slope of the line in the integrated phase difference diagram represents the phase difference change rate ω [deg / sec].

[0059] The control device 7 outputs a drive command to the clutch actuator 5 to engage the dog clutch 10 at a future engagement time after the rotational speed difference reaches the target rotational speed difference ωs. The control device 7 of this embodiment adjusts the phase difference so that one of the future engagement times coincides with the target completion time tall, which is the time after the adjustment reference time t1 by the target completion time Tall. In other words, the target completion time tall is the target timing for executing engagement.

[0060] The third diagram in Figure 10 shows the ON / OFF state of the drive command for the clutch actuator 5. The bottom diagram in Figure 10 shows the stroke of the clutch actuator 5. The control device 7 starts the advance operation of the clutch actuator 5 at time tpre, which is a predetermined advance operation time Tpre before the target completion time tall. The clutch actuator 5 reaches the standby position of the standby stroke Stsb at time tsb. Thereafter, at the target completion time tall, the control device 7 moves the clutch actuator 5 to the full stroke Stfl to fully engage the dog clutch 10.

[0061] Next, control of the rotation speed difference will be described. Specifically, control for changing the gradient, which is the rate of change of the rotation speed difference over time, as the "change characteristic of the input / output shaft rotation speed difference." In both the comparative example and the first embodiment, the initial gradient from the adjustment reference time t1 to the arbitrary phase difference detection time td is set to a0. Here, the initial gradient a0 during phase difference detection is set to have a smaller absolute value, i.e., a gentler slope, than the gradient a00 during the period from the start of synchronization operation to the adjustment reference time t1 during which no phase difference is detected. This setting is effective in shortening the phase difference detection time.

[0062] In the comparative example, the initial gradient a0 is maintained constant from the adjustment reference time t1 to the arrival time tt at which the rotational speed difference reaches the target rotational speed difference ωs. In contrast, in the first embodiment, the control device 7 calculates the target gradient ac, which is a target value of the gradient, based on information acquired at the arbitrary phase difference detection time td, and changes the initial gradient a0 to the target gradient ac. In the first embodiment, the initial engagement timing after the adjustment reference time t1 is set to the arbitrary phase difference detection time td.

[0063] The control device 7 adjusts the phase difference by changing the gradient at the arbitrary phase difference detection time td, thereby causing one of the future engagement times to coincide with the target completion time tall. If the arbitrary phase difference detection time td is the present, in the first embodiment, the current next engagement time, i.e., the first future engagement time, is controlled to coincide with the target completion time tall. When the nth future engagement time is controlled to coincide with the target completion time tall, n is referred to as the "number of adjustment cycles." In the first embodiment, "n=1."

[0064] The target gradient ac is set to have a larger absolute value than the initial gradient a0, i.e., a steeper slope. Therefore, the arrival time ts, at which the rotational speed difference reaches the target rotational speed difference ωs, is earlier than the arrival time tt in the comparative example. As a result, engagement is performed at the target completion time tall, which is earlier than the engagement execution time tz in the comparative example, enabling power transmission. This achieves clutch engagement with higher accuracy and response than in the comparative example.

[0065] A few notes about the time symbols in the diagram: Td represents the initial gradient duration from the adjustment reference time t1 to the arbitrary phase difference detection time td; Ts represents the target gradient duration from the arbitrary phase difference detection time td to the arrival time ts; and Tc represents the target rotation speed difference duration from the arrival time ts to the target completion time tall. The sum of Td, Ts, and Tc is equal to the target completion time Tall (Td + Ts + Tc = Tall).

[0066] Next, the theoretical formula for calculating the target gradient ac will be explained. The target gradient ac is defined by equation (2). Furthermore, in the rotation speed difference diagram of FIG. 10, when the sum of the area of ​​right-angled triangle A and the area of ​​rectangle B is equal to the integrated phase difference from the arbitrary phase difference detection time td to the target completion time tall, equation (3) holds. The "10" on the right side of equation (3) represents the pitch angle P (=10 degrees) of a gear with 36 teeth. The units of each parameter are as follows:

[0067] Rotation speed difference: ωd, ωs [deg / sec] Time: Ts, Td, Tall [sec] Gradient: ac [deg / sec] ２ ] Phase difference: Δθt, Δθd [deg]

[0068]

[0069] By eliminating Ts from equations (2) and (3), equation (4) for determining ac is obtained.

[0070]

[0071] Using equation (4), the control device 7 calculates the target gradient ac based on the following six parameters. Note that the number of adjustment periods n is set appropriately. If these parameters can be obtained, the control device 7 does not need to predict the future engagement timing at the arbitrary phase difference detection time td. - Target completion time Tall - Time Td from the adjustment reference time t1 to the arbitrary phase difference detection time td - Phase difference Δθd detected at the arbitrary phase difference detection time td - Target phase difference Δθt at the time of engagement - Rotational speed difference ωd at the arbitrary phase difference detection time td - Target rotational speed difference ωs

[0072] Of these, the target completion time Tall, the target phase difference Δθt at the time of engagement, and the target rotational speed difference ωs are stored as default values. However, as described above with reference to Figure 6, if a factor that delays the operation of the clutch actuator 5 occurs, the target completion time correction unit 79 corrects the target completion time Tall in accordance with the operation delay time estimated by the operation delay time estimator 78.

[0073] The control device 7 acquires information on the following three parameters at the arbitrary phase difference detection time td: the time Td from the adjustment reference time t1 to the arbitrary phase difference detection time td, the phase difference Δθd detected at the arbitrary phase difference detection time td, and the rotation speed difference ωd at the arbitrary phase difference detection time td.

[0074] The concept of equation (3) is expressed as follows: The control device 7 calculates the target gradient ac so that the "time integral value of the value obtained by converting the rotation speed difference during the period from the arbitrary phase difference detection time td to the target completion time tall into the phase difference change rate" matches the phase difference obtained by adding "an integer multiple of the pitch angle of the first engagement tooth 13 and the second engagement tooth 14" to "the difference between the target phase difference Δθt during engagement and the phase difference Δθd detected at the arbitrary phase difference detection time td."

[0075] The clutch engagement control according to the first embodiment will be described with reference to the flowchart in Figure 11. In the description of the flowchart, the symbol "S" denotes a step. In order to share the step numbers with Figure 21 of the eighth embodiment, S15 to S17 are omitted in Figure 11.

[0076] After the synchronization operation is initiated, the rotation speed difference gradually decreases. In S11, at adjustment reference time t1, the rotation speed difference reaches ω0, which allows the phase difference to be detected by the phase difference sensor 6. Thereafter, S12 to S18 are executed regarding the MG rotation. In S12, the control device 7 detects the phase difference Δθd at an arbitrary phase difference detection time td. In the first embodiment, the initial engagement timing after adjustment reference time t1 is detected at the arbitrary phase difference detection time td.

[0077] The control device 7 acquires information on the time Td from the adjustment reference time t1 to the arbitrary phase difference detection time td, the phase difference Δθd detected at the arbitrary phase difference detection time td, and the rotational speed difference ωd at the arbitrary phase difference detection time td. The control device 7 also stores information on the target completion time Tall, the target engagement phase difference Δθt, and the target rotational speed difference ωs. In S13, the control device 7 starts phase difference adjustment based on this information.

[0078] In S14, the control device 7 calculates the target gradient ac and changes the initial gradient a0 to the target gradient ac. In S18, the rotation speed difference reaches the target rotation speed difference ωs at the arrival time ts when the target gradient duration Ts has elapsed since the arbitrary phase difference detection time td.

[0079] After S11, S21 to S23 are executed in parallel with S12 to S18 regarding the operation of the clutch actuator 5. In S21, the control device 7 calculates a time tpre that is a preceding operation time Tpre before the target completion time tall. In S22, the control device 7 starts the preceding operation of the clutch actuator 5 at time tpre. In S23, the clutch actuator 5 reaches the standby position at time tsb.

[0080] After S18 regarding MG rotation and S23 regarding ACT operation, in S31, the completion target time Tall has elapsed from the adjustment reference time t1. In S32, the engagement of the dog clutch 10 is executed.

[0081] As described above, in the first embodiment, the control device 7 calculates the target gradient ac based on information acquired at the arbitrary phase difference detection time td, and changes the initial gradient a0 to the target gradient ac, thereby matching the future first engagement time with the target completion time tall. This allows for highly accurate phase difference adjustment and improves clutch engagement responsiveness.

[0082] For comparison, a different control method is assumed. In this assumed control, the future engagement time is predicted and then the engagement time is moved closer to the arrival time. In this case, if torque is input to the input shaft in an attempt to move the engagement time closer to the arrival time, the input shaft rotation speed may change, causing the arrival time to shift and reducing the accuracy of the phase difference adjustment. In contrast, in this embodiment, the rotation speed difference gradient is changed and the phase difference adjustment is performed simultaneously based on information acquired at the arbitrary phase difference detection time td, thereby achieving highly accurate phase difference adjustment. Furthermore, in this embodiment, the future engagement time does not necessarily have to be predicted.

[0083] Next, with reference to Figures 12 to 17, phase difference adjustment according to second to seventh embodiments will be described in order as variations different from the first embodiment. Figures 12 to 17 correspond to Figure 10 of the first embodiment, and symbols for time, duration, rotation speed difference, gradient, phase difference, etc. are the same as those in Figure 10. The two-dot chain line indicates control of a comparative example in which phase difference adjustment is not performed. The diagrams of the ACT drive request and ACT stroke are omitted because they are the same as Figure 10.

[0084] In all embodiments, the target phase difference Δθt at the time of engagement is "Δθt = +5 deg." Furthermore, except for the fourth embodiment, the phase difference Δθd detected at the arbitrary phase difference detection time td is the phase difference at which the dog clutch 10 can be engaged, i.e., "Δθd = +5 deg." At this time, "Δθt - Δθd = 0." In other words, except for the fourth embodiment, the engagement timing is detected at the arbitrary phase difference detection time td. Furthermore, except for the third and fourth embodiments, the first engagement timing after the adjustment reference time t1 is detected at the arbitrary phase difference detection time td.

[0085] 12 , the target gradient ac is calculated by setting the adjustment period number n to 2 so that the timing of the second future engagement after the arbitrary phase difference detection time td coincides with the target completion time tall. In this manner, the target gradient ac is calculated so that the timing of the second or subsequent future engagement coincides with the target completion time tall, and the initial gradient a0 may be changed to the target gradient ac.

[0086] 13, the second engagement time after the adjustment reference time t1 is set to the arbitrary phase difference detection time td. In this manner, the second or more engagement times after the adjustment reference time t1 may be set to the arbitrary phase difference detection time td.

[0087] 14, the phase difference Δθd detected at the arbitrary phase difference detection time td is a phase difference where "Δθd = 0", which corresponds to the antinode of the beat wave (see FIG. 8). At this time, "n = 1" and "Δθt - Δθd = +5 deg". In this way, the phase difference Δθd detected at the arbitrary phase difference detection time td may be any phase difference other than the phase difference at which the dog clutch 10 can be engaged.

[0088] 15 and 16 , the control device 7 changes the target rotation speed difference from a reference value ωs to a changed value ωsc in addition to changing the gradient as the “change characteristic of the input / output shaft rotation speed difference” based on information acquired at an arbitrary phase difference detection time td. The “information acquired by the control device at an arbitrary phase difference detection time td” includes the time Td, the phase difference Δθd, and the rotation speed difference ωd, as well as the calculation parameters for the target gradient ac.

[0089] 15 and 16, the changed target rotation speed difference ωsc is set to a value smaller than the reference value ωs (ωsc<ωs). The rotation speed difference decreases to the changed target rotation speed difference ωsc along the target gradient ac, so the arrival time ts is slightly delayed.

[0090] In the fifth embodiment, the target rotation speed difference is returned to the reference value ωs before the target completion time tall, and the engagement shock during engagement is managed at a standard level. In the sixth embodiment, the changed target rotation speed difference ωsc is maintained until the target completion time tall. Therefore, the engagement shock during engagement can be reduced below the standard level.

[0091] 17 , the control device 7 changes the target rotation speed difference from a reference value ωs to a changed value ωsc without changing the gradient as the “change characteristic of the input / output shaft rotation speed difference” based on information acquired at an arbitrary phase difference detection time td. The changed target rotation speed difference ωsc is set to a value greater than the reference value ωs (ωsc>ωs).

[0092] Here, the reference value ωs of the target rotation speed difference is set to a small value obtained by subtracting a margin from the allowable limit value ωs0 for engagement shock. Therefore, it is possible to change the target rotation speed difference to a larger value ωsc within the range of the reference value ωs from the margin in order to avoid the effects of engagement shock. By increasing the target rotation speed difference, i.e., by decreasing the input shaft rotation speed Nin, the phase difference period becomes shorter, and the target completion time tall is advanced compared to the comparative example. Therefore, the responsiveness of the clutch engagement can be improved.

[0093] Eighth Embodiment Next, with reference to FIGS. 18 to 21, a phase difference adjustment according to an eighth embodiment will be described. The phase difference adjustment method includes changing the target gradient ac. In the first to sixth embodiments described above, the phase difference Δθd for the purpose of phase difference adjustment is detected once at an arbitrary phase difference detection time td between the adjustment reference time t1 and the arrival time ts. During this period, phase difference detection for monitoring the phase difference, for example, may be performed any number of times, but the phase difference Δθd that is reflected in the phase difference adjustment is detected at least once.

[0094] In contrast, the eighth embodiment is based on the premise that phase difference detection for the purpose of phase difference adjustment is performed multiple times at multiple arbitrary phase difference detection times between the adjustment reference time t1 and the arrival time ts. Here, a case will be described in which phase differences Δθd1 to Δθd3 are detected three times at three arbitrary phase difference detection times td1 to td3. Particularly in the eighth embodiment, it is preferable for the control device 7 to predict future phase differences. In this case, the rotation speed difference change characteristic calculation unit 74 in FIG. 6 acquires the phase difference estimated by the current phase difference estimation unit 73.

[0095] 18, 19, and 20 are time charts of phase difference adjustment at arbitrary phase difference detection times td1, td2, and td3, respectively, at which the first, second, and third engagement times after the adjustment reference time t1 are detected. The first and second time charts show provisional operation, and the third time chart shows final operation. As in the figures of the above embodiment, the two-dot chain line shows control in a comparative example in which phase difference adjustment is not performed.

[0096] 18, at the first arbitrary phase difference detection time td1, a first target gradient ac1 is calculated based on the time Td1, the phase difference Δθd1, and the rotation speed difference ωd1, and the initial gradient a0 is changed to the first target gradient ac1. At this point, it is assumed that the first target gradient ac1 will be maintained until the arrival time ts, and future operation is tentatively predicted.

[0097] However, during control after the arbitrary phase difference detection time td1, the actual phase difference may deviate from the target phase difference depending on the control period, the rotation speed reading accuracy, and the reading accuracy of the phase difference sensor. Alternatively, as shown by the dashed dotted line, the actual rotation speed difference may change without following the target gradient ac.

[0098] Therefore, the control device 7 recalculates the target gradients ac2 and ac3 at the arbitrary phase difference detection times td2 and td3, which are the second and third opportunities to detect the timing of engagement, and updates the previously calculated target gradients. In Figures 19 and 20, the dashed lines indicate the operation calculated at the first arbitrary phase difference detection time td1.

[0099] As shown in Fig. 19 , at the second arbitrary phase difference detection time td2, a second target gradient ac2 is calculated based on the time Td2, the phase difference Δθd2, and the rotation speed difference ωd2, and the previous value of the first target gradient ac1 is updated to the current value of the second target gradient ac2. At this time, the currently detected phase difference Δθd2 is updated by referring to the phase difference predicted at the previous arbitrary phase difference detection time td1, thereby improving accuracy. In the example of Fig. 19 , a discrepancy occurs between the target motion based on the first target gradient ac1 and the actual motion, and the second target gradient ac2 calculated at the second arbitrary phase difference detection time td2 is a different value from the first target gradient ac1.

[0100] As shown in FIG. 20 , at the third arbitrary phase difference detection time td3, a third target gradient ac3 is calculated based on the time Td3, the phase difference Δθd3, and the rotation speed difference ωd3. The third target gradient ac3 is updated from the previous value, the second target gradient ac2, to the current value, the third target gradient ac3. Similarly, the currently detected phase difference Δθd3 is calculated by referring to the phase difference predicted at the previous arbitrary phase difference detection time td2, thereby improving accuracy. In the example of FIG. 20 , there is almost no discrepancy between the target motion based on the second target gradient ac2 and the actual motion. Therefore, the third target gradient ac3 calculated at the third arbitrary phase difference detection time td3 is approximately the same value as the second target gradient ac2.

[0101] The calculation formulas for the target gradients ac1 to ac3 at the arbitrary phase difference detection times td1 to td3 are shown in equations (5.1) to (5.3). If one arbitrary phase difference detection time is set for each phase period after the adjustment reference time t1, the number of adjustment periods n decreases by one each time a phase difference is detected. In the example of FIGS. 18 to 20, the first time is "n=4," the second time is "n=3," and the third time is "n=2." In addition, in this example, the detected phase differences Δθd1, Δθd2, and Δθd3 and the engagement target phase difference Δθt are "Δθd1 = Δθd2 = Δθd3 = Δθt = +5 deg."

[0102]

[0103] Figure 21 shows a flowchart of clutch engagement control according to the eighth embodiment. Compared to Figure 11, Figure 21 adds loop steps S15 to S17. S18 also serves as a step for determining whether the loop has ended. The other steps are essentially the same as those in Figure 11, so the same step numbers are used and their explanations are omitted. Note that the symbols have been changed from td to td1 in S12, Δθd to Δθd1, and ac to ac1 in S14.

[0104] In S15, the phase difference Δθk for the kth time (k≧2) is detected at the arbitrary phase difference detection time tdk. In S16, the control device 7 updates the target gradient ac(k−1) calculated at the previous arbitrary phase difference detection time td(k−1) to the target gradient ack calculated at the current arbitrary phase difference detection time tdk. Accordingly, in S17, the future engagement timing is updated.

[0105] In S18, it is determined whether the rotation speed difference has reached the target rotation speed difference ωs. If the answer is NO in S18, S15 to S17 are repeated. If the answer is YES in S18, the update of the target gradient is completed and the process proceeds to S31. When the completion target time Tall has elapsed from the adjustment reference time t1 in S31, the engagement of the dog clutch 10 is executed in S32.

[0106] As described above, in the eighth embodiment, by repeatedly updating the target gradients ac1 to ack through feedback control using phase difference detection multiple times between the adjustment reference time t1 and the arrival time ts, it is possible to achieve clutch engagement with higher accuracy and higher response.

[0107] 1, 5, etc. has a face-type gear configuration in which the clutch members 11, 12 themselves move relative to one another 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 employed in which the clutch members are stationary and a movable sleeve is provided as a separate component as an intermediary member.

[0108] 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 mesh clutch. The detection portion of the phase difference sensor is adjusted so that different sensor signals are output depending on whether the state is engaged or disengaged.

[0109] (b) The dog clutch 10 is not limited to being provided between the rear wheel MG 82 and the rear wheels 92 in the 2WD / 4WD switchable vehicle 90 illustrated in FIG. 1 , but may also be provided, for example, between the front wheel MG and the front wheels in a front-wheel drive (FF) vehicle.

[0110] (c) The phase difference sensor 6 is not limited to one that detects the total area of ​​the engaging teeth 13, 14 within the detection range SA as exemplified in Figures 5 and 7, but may be one that can detect information correlated with the difference in rotational position between the input shaft 3 and the output shaft 4 and convert it into a phase difference. Furthermore, the phase difference may be defined as 0 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 with 36 teeth varies within a range of 0 to +10 degrees. Regardless of the definition of the phase difference, the relative value of "Δθt - Δθd" in equation (4) remains the same.

[0111] (d) The rotational drive source connected to the input shaft 3 is not limited to the MG 82, 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.

[0112] (e) The synchronization operation is not limited to an operation in which the output shaft rotation speed Nout (i.e., vehicle speed) is constant and only the input shaft rotation speed Nin gradually increases, but may also involve changing both the output shaft rotation speed Nout and the input shaft rotation speed Nin so that they approach each other.

[0113] (f) In the synchronization operation shown in Figure 9, the input shaft 3 is stopped in the disengaged state, and after the control device 7 receives an engagement command, the input shaft rotation speed Nin increases from 0 rpm toward the target rotation speed N_tgt. Alternatively, the input shaft rotation speed Nin may be maintained at a predetermined target idle rotation speed in the disengaged state. For example, by setting the target idle rotation speed higher as the vehicle speed increases, the synchronization operation time at high speeds can be shortened.

[0114] 2, it is necessary to quickly switch from 2WD to 4WD in the following situations: (1) when it is raining, snowing, or the road is frozen; (2) when turning a sharp curve; and (3) when braking at a red light or at the end of a traffic jam. Therefore, by setting the target idle speed high in these situations, the synchronization operation time can be shortened. However, since this can adversely affect power consumption, it is preferable to set the target idle speed appropriately according to the vehicle's operating conditions, rather than setting it higher than necessary.

[0115] As described above, the present disclosure is not limited to the above-described embodiments, and can be embodied in various forms without departing from the spirit of the present disclosure.

[0116] (Disclosure of Technical Ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be described in a multiple dependent form, with the subsequent clause alternatively referring to the preceding clause. Furthermore, some clauses may be described in a multiple dependent form, with the subsequent clause referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0117] (Technical Idea 1) A dog clutch (10) having a first clutch member (11) connected to an input shaft (3) and having a plurality of first engagement teeth (13) arranged in the 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 the circumferential direction that can mesh with the first engagement teeth directly or via an intermediary member, wherein the first clutch member and the second clutch member are switched between an engaged state and a released state; 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 intermediary member is used, moves the intermediary member relative to the first clutch member and the second clutch member in the axial direction; and a phase difference sensor (6) that detects a phase difference between the first clutch member and the second clutch member. a control device (7) that controls an input / output shaft rotation speed difference, which is the difference between the rotation speed of the input shaft and the rotation speed of the output shaft, and performs a synchronization operation of gradually reducing the input / output shaft rotation speed difference until it reaches a target rotation speed difference (ωs) at which the dog clutch can be engaged by an engagement command to engage the dog clutch in a released state, and detects a current engagement time based on an output of the phase difference sensor for an engagement time at which the dog clutch will be engageable in the synchronization operation, and outputs a drive command to the clutch actuator to engage the dog clutch at a future engagement time after the input / output shaft rotation speed difference reaches the target rotation speed difference, and the control device performs a synchronization operation of gradually reducing the input / output shaft rotation speed difference, which is the difference between the rotation speed of the input shaft and the rotation speed of the output shaft, by an engagement command to engage the dog clutch in a released state A dog clutch engagement control system that adjusts the phase difference between the first clutch member and the second clutch member by changing the change characteristics of the input / output shaft rotational speed difference so that any of the future engagement times coincides with a target completion time (tall) that is a time that is a target completion time (Tall) after the adjustment reference time.(Technical Idea 2) A dog clutch engagement control system according to Technical Idea 1, wherein a rate of change of the input / output shaft rotational speed difference is defined as a gradient, and the gradient during the period from the adjustment reference time to the arbitrary phase difference detection time is defined as an initial gradient (a0), the control device calculates a target gradient (ac) that is a target value of the gradient based on information acquired at the arbitrary phase difference detection time, and changes the initial gradient to the target gradient. (Technical Idea 3) A dog clutch engagement control system according to Technical Idea 2, wherein the control device calculates the target gradient based on the target completion time (Tall), the time (Td) from the adjustment reference time to the arbitrary phase difference detection time, the phase difference (Δθd) detected at the arbitrary phase difference detection time, the target phase difference at engagement (Δθt), the input / output shaft rotational speed difference (ωd) at the arbitrary phase difference detection time, and the target rotational speed difference (ωs). (Technical Idea 4) The control device calculates the target gradient so that a time integral of a value obtained by converting the input / output shaft rotational speed difference during the period from the arbitrary phase difference detection time to the target completion time into a phase difference change rate coincides with a phase difference obtained by adding an integer multiple of the pitch angle of the first engagement tooth and the second engagement tooth to the difference between a target phase difference (Δθt) at the time of engagement and the phase difference (Δθd) detected at the arbitrary phase difference detection time. (Technical Idea 5) The dog clutch engagement control system according to any one of Technical Ideas 1 to 4, wherein the phase difference detected at the arbitrary phase difference detection time is a phase difference at which the dog clutch can be engaged. (Technical Idea 6) The dog clutch engagement control system according to any one of Technical Ideas 1 to 5, wherein the control device changes the target rotational speed difference based on information acquired at the arbitrary phase difference detection time. (Technical Idea 7) A dog clutch engagement control system as described in any one of Technical Ideas 1 to 6, wherein the control device starts the advance operation of the clutch actuator at a time (tpre) that is a predetermined advance operation time (Tpre) before the target completion time, and when a factor that delays the operation of the clutch actuator occurs, corrects the target completion time according to the operation delay time.(Technical Idea 8) A dog clutch engagement control system as set forth in any one of Technical Ideas 2 to 4, wherein, on the premise that phase difference detection is performed a plurality of times at a plurality of the arbitrary phase difference detection times (td1 to td3) from the adjustment reference time to the arrival time (ts) at which the input / output shaft rotational speed difference reaches the target rotational speed difference, the control device updates the target gradient calculated at the previous arbitrary phase difference detection time to the target gradient calculated at the current arbitrary phase difference detection time.

[0118] 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.

[0119] The present disclosure has been described based on the embodiments. However, the present disclosure is not limited to the embodiments and structures. The present disclosure also encompasses various modifications and variations within the scope of equivalents. Furthermore, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. A meshing clutch (10) having a first clutch member (11) connected to an input shaft (3) and having a plurality of first engagement teeth (13) arranged in the 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 the circumferential direction that can mesh with the first engagement teeth directly or via an intermediate member, the first clutch member and the second clutch member being switched between an engaged state and a released state; 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 intermediate member is used, moves the intermediate member relative to the first clutch member and the second clutch member in the axial direction; a phase difference sensor (6) that detects a phase difference between the first clutch member and the second clutch member; a control device (7) that controls an input / output shaft rotation speed difference, which is the difference between the rotation speed of the input shaft and the rotation speed of the output shaft, performs a synchronization operation of gradually reducing the input / output shaft rotation speed difference until it reaches a target rotation speed difference (ωs) at which the dog clutch can be engaged, by an engagement command to engage the dog clutch in a released state, detects a current engagement time based on an output of the phase difference sensor for an engagement time at which the dog clutch will be engageable in the synchronization operation, and outputs a drive command to the clutch actuator to engage the dog clutch at the future engagement time after the input / output shaft rotation speed difference reaches the target rotation speed difference, and the control device performs a synchronization operation based on information acquired at an arbitrary phase difference detection time (td) at which an arbitrary phase difference is detected based on the output of the phase difference sensor after an adjustment reference time (t1) at which the input / output shaft rotation speed difference reaches a rotation speed difference (ω0) at which the phase difference can be detected by the phase difference sensor, a control circuit for controlling a phase difference between the first clutch member and the second clutch member by changing a change characteristic of the input / output shaft rotational speed difference so that any one of the future engagement times coincides with a target completion time (tall), which is a time that is a target completion time (Tall) after the adjustment reference time.

2. The dog clutch engagement control system of claim 1, wherein the rate of change of the difference in the input / output shaft rotational speeds is defined as a gradient, and the gradient during the period from the adjustment reference time to the arbitrary phase difference detection time is an initial gradient (a0), the control device calculates a target gradient (ac), which is a target value of the gradient, based on information acquired at the arbitrary phase difference detection time, and changes from the initial gradient to the target gradient.

3. The control device calculates the target gradient based on the target completion time (Tall), the time (Td) from the adjustment reference time to the arbitrary phase difference detection time, the phase difference (Δθd) detected at the arbitrary phase difference detection time, the target phase difference at engagement (Δθt), the input / output shaft rotational speed difference (ωd) at the arbitrary phase difference detection time, and the target rotational speed difference (ωs).

4. The control device calculates the target gradient so that the time integral value of the input / output shaft rotational speed difference converted into a phase difference change rate during the period from the arbitrary phase difference detection time to the target completion time coincides with a phase difference obtained by adding an integer multiple of the pitch angle of the first engaging tooth and the second engaging tooth to the difference between the target phase difference (Δθt) at the time of engagement and the phase difference (Δθd) detected at the arbitrary phase difference detection time.

5. A dog clutch engagement control system according to claim 1 or 2, wherein the phase difference detected at said arbitrary phase difference detection time is a phase difference at which said dog clutch can be engaged.

6. A dog clutch engagement control system as set forth in claim 1 or 2, wherein said control device changes said target rotation speed difference based on information acquired at said arbitrary phase difference detection time.

7. A mesh clutch engagement control system as described in claim 1, wherein the control device starts the advance operation of the clutch actuator at a time (tpre) a predetermined advance operation time (Tpre) before the target completion time, and if a factor that delays the operation of the clutch actuator occurs, corrects the target completion time in accordance with the operation delay time.

8. A dog clutch engagement control system as described in claim 2, wherein, on the assumption that phase difference detection is performed a plurality of times at a plurality of the arbitrary phase difference detection times (td1 to td3) between the adjustment reference time and the arrival time (ts) at which the input / output shaft rotational speed difference reaches the target rotational speed difference, the control device updates the target gradient calculated at the previous arbitrary phase difference detection time to the target gradient calculated at the current arbitrary phase difference detection time.

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