Damage estimation device for meshing-type engagement mechanism

Abstract

To provide a damage estimation device for a meshing-type engagement mechanism capable of properly estimating damage on the meshing-type engagement mechanism.SOLUTION: A damage estimation device for a meshing-type engagement mechanism comprises: (step S2) estimating a collision torque acting on dog teeth on the basis of an angular acceleration of any one rotation member of an input side rotation member and an output side rotation member whose rotation speed is varied according to meshing of the dog teeth and a moment of inertia of a member rotating integrally with one rotation member; (step S3) acquiring an accumulated damage accumulating on the dog teeth on the basis of the estimated collision torque and a repetition number of breaking of the dog teeth corresponding to the collision torque; and (step S5) issuing a warning when the accumulated damage becomes a prescribed limitation damage or more.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an apparatus for estimating damage to an engagement type engagement mechanism that integrates two rotating members by meshing dog teeth.

Background Art

[0002] Patent Document 1 describes an engagement type engagement mechanism including a drive gear to which torque is transmitted from a drive power source, a forward gear and a reverse gear that mesh with the drive gear and are provided so as to be relatively rotatable with respect to an output shaft, a dog clutch that is provided so as to be integrally rotatable with the output shaft and meshes with the forward gear or the reverse gear by moving in the axial direction of the output shaft, and an actuator that operates the dog clutch. Further, Patent Document 1 describes an apparatus that accumulates the number of operations of the actuator and determines the replacement timing of the actuator when the accumulated number reaches a predetermined number.

[0003] Patent Document 2 describes a stepped transmission that can set a plurality of shift stages. This stepped transmission includes a sleeve that is provided so as to be integrally rotatable with the output shaft and moves in the axial direction of the output shaft by a shift operation, and a synchronizer ring that applies a synchronous load to a gear connected to the drive power source by being pressed as the sleeve moves. Further, Patent Document 2 describes an apparatus that notifies that replacement of the synchronizer is necessary when the cumulative value of the absorbed energy of the synchronizer reaches an upper threshold value. The absorbed energy is obtained by multiplying the difference in rotational speed (input rotational speed) between the rotational speed of the gear at the start of synchronization and the rotational speed of the gear at the completion of synchronization by the inertia based on the gear stage after shifting.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The device for determining the replacement timing of the actuator described in Patent Document 1 is configured to determine the replacement timing of the actuator based on the number of operating times of the actuator. However, in the meshing engagement mechanism, the degree of fatigue damage varies depending on the magnitude of the collision load acting on the dog teeth during meshing. Therefore, the device described in Patent Document 1 cannot be immediately adopted to determine the replacement timing of the meshing engagement mechanism, and there is a possibility that the replacement timing cannot be appropriately determined.

[0006] The device described in Patent Document 2 is configured to determine the replacement timing of the synchronization device according to the cumulative value of the absorbed energy based on the change amount of the rotational speed of the gear before and after the start of synchronization and the inertia torque. On the other hand, in a meshing engagement mechanism not provided with a synchronization device such as a synchronizer, a collision load (collision stress) acts on the tooth surface during the engagement of the dog teeth, and the fatigue limit that the dog teeth can withstand varies according to the collision load (collision stress). Therefore, there is a possibility that the fatigue limit of the meshing engagement mechanism cannot be appropriately determined according to the cumulative value of the absorbed energy.

[0007] This invention has been made paying attention to the above technical problems, and an object thereof is to provide a damage estimation device for a meshing engagement mechanism that can appropriately estimate the damage of the meshing engagement mechanism.

Means for Solving the Problems

[0008] In order to achieve the above object, the present invention provides an engagement type engagement mechanism damage estimation device including an input side rotating member and an output side rotating member that rotate relative to each other, wherein a movable member, which is one of the input side rotating member and the output side rotating member, is configured to approach and separate from the other rotating member, and dog teeth that mesh with each other when the movable member approaches the other rotating member are formed on the input side rotating member and the output side rotating member. The damage estimation device includes a controller that estimates damage to the engagement type engagement mechanism. The controller estimates a collision torque acting on the dog teeth based on an angular acceleration of one of the input side rotating member and the output side rotating member, whose rotational speed changes with the meshing of the dog teeth, and a moment of inertia of a member that rotates integrally with the one rotating member, and obtains cumulative damage accumulated on the dog teeth based on the estimated collision torque and the number of fracture repetitions of the dog teeth corresponding to the collision torque.

Advantages of the Invention

[0009] The damage estimation device for the engagement type engagement mechanism according to the present invention estimates a collision torque acting on the dog teeth based on an angular acceleration of one rotating member, whose rotational speed changes with the meshing of the dog teeth, and a moment of inertia of a member that rotates integrally with the rotating member, and obtains cumulative damage accumulated on the dog teeth based on the estimated collision torque and the number of fracture repetitions of the dog teeth corresponding to the collision torque. That is, the degree of influence of the damage accumulated on the dog teeth is obtained according to the torque acting on the dog teeth. As a result, even if the torque acting on the dog teeth during meshing varies for each meshing operation, the damage accumulated on the dog teeth can be estimated according to the torque acting on the dog teeth for each meshing operation, so that the damage to the engagement type engagement mechanism can be appropriately estimated.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0011] Embodiments of the present invention will be described with reference to the drawings. It should be noted that the embodiments described below are merely examples when implementing the present invention and do not limit the present invention.

[0012] The meshing engagement mechanism in an embodiment of the present invention can be a meshing engagement mechanism as a starting clutch mechanism that selectively shuts off the transmission of torque between a driving power source of a vehicle such as an engine or a motor and a driving wheel, a meshing engagement mechanism provided in a transmission mechanism that changes the gear ratio (rotation speed ratio) between the driving power source and the driving wheel, or a meshing engagement mechanism provided in a power split mechanism for changing the torque ratio transmitted to the driving wheel side among the torques of the driving power source, and can be targeted at meshing engagement mechanisms provided in various mechanisms.

[0013] The transmission mechanism may be, for example, a transmission mechanism including a plurality of planetary gear mechanisms, configured to engage at least one pair of rotating elements by a meshing engagement mechanism according to a selected gear stage, or to engage a predetermined rotating element with a fixed member such as a case by a meshing engagement mechanism. Or, it may be a transmission mechanism in which a plurality of gear pairs are provided in parallel and configured to engage a corresponding gear pair with an input shaft or an output shaft by a meshing engagement mechanism according to a selected gear stage.

[0014] Further, the power split mechanism may include, for example, two planetary gear mechanisms, with a driving power source connected to the input element, a motor connected to the reaction force element, a driving wheel further connected to the output element, and a torque ratio for splitting the torque of the driving power source between the motor and the driving wheel set to a first torque ratio by connecting a predetermined pair of rotating elements by a meshing engagement mechanism, and configured to set the torque ratio to a second torque ratio by connecting another predetermined pair of rotating elements by a meshing engagement mechanism.

[0015] The meshing engagement mechanism can be configured in the same manner as a conventional meshing engagement mechanism. That is, it includes an input-side rotating member and an output-side rotating member that rotate relative to each other, and by approaching one of the pair of rotating members (the movable member) to the other rotating member (the non-movable member), the dog teeth formed on the rotating members of each other are engaged, and by separating the movable member from the non-movable member, the meshing of the dog teeth is released. The dog teeth may be formed to protrude from the opposing surfaces facing each other to the other rotating member, or may be formed on the outer peripheral surface of one rotating member and the inner peripheral surface of the other rotating member. Further, the movable member may rotate integrally with one of the target members for transmitting torque and include a sleeve that moves by a shift mechanism.

[0016] Also, the meshing engagement mechanism in the embodiment of the present invention does not include a synchronization mechanism for reducing the rotational speed difference between the pair of rotating members. Therefore, for example, in the case of the power split mechanism configured as described above, by controlling the rotational speed of the motor, the rotational speed of either one of the pair of rotating members is increased or decreased, and the rotational speed difference between the pair of rotating members is reduced to a predetermined difference or less determined in advance, and the movable member is brought close to the non-movable member side to engage. In that case, the tip of the dog tooth (the position where it starts to mesh with the other dog tooth) may be formed to be inclined so that the rotational speed difference between the pair of rotating members can be engaged when it is at a predetermined difference or less.

[0017] When the pair of rotating members engage with each other while rotating relative to each other at a rotational speed difference of not more than a predetermined difference, a collision load (collision stress) acts on the dog teeth. Therefore, since the durability of the dog teeth decreases according to the collision load and the number of repetitions thereof, the damage estimation device in the embodiment of the present invention is configured to estimate the damage of the meshing engagement mechanism based on the collision load acting on the dog teeth and the number of collisions thereof.

[0018] FIG. 1 shows an example of an electronic control unit 1 that estimates damage to a meshing engagement mechanism and a communication system between the electronic control unit 1. The electronic control unit (hereinafter referred to as ECU) 1 shown in FIG. 1 is mainly composed of a microcomputer, similar to the ECU provided in a conventional vehicle, and signals are input from various sensors provided in the vehicle. It is configured to estimate the damage of the meshing engagement mechanism based on the input signals, arithmetic expressions stored in advance, maps, and the like. Note that the ECU 1 corresponds to the "controller" in the embodiment of the present invention.

[0019] In the example shown in FIG. 1, a transmission (TM) 2 having a meshing engagement mechanism is provided, and an input rotation speed sensor 4 for detecting the rotation speed of the input shaft 3 of the transmission 2 and an output rotation speed sensor 6 for detecting the rotation speed of the output shaft 5 are provided. Each of the rotation speed sensors 4 and 6 is a sensor for obtaining the rotation speed difference between a pair of rotating members constituting the meshing engagement mechanism, and is not limited to those provided on the input shaft 3 or the output shaft 5. For example, in the case of a power split mechanism configured as described above, a crank angle sensor for detecting the engine rotation speed and a resolver for detecting the motor rotation speed may be used. In the example shown in FIG. 1, when the estimated value of the damage to the meshing engagement mechanism exceeds a predetermined value, a warning is issued to the occupant to prompt replacement of the meshing engagement mechanism (or the transmission 2), and a signal is output from the ECU 1 to a warning device 7 such as an indicator lamp for issuing the warning.

[0020] FIG. 2 shows a flowchart for explaining a control example executed by the ECU 1. The control example shown in FIG. 2 is a control example for estimating damage during a shift accompanied by engagement of a meshing engagement mechanism. When shifting accompanied by engagement of such a meshing engagement mechanism, a relatively large impact load (impact stress) acts on the dog teeth from the time when the meshing engagement mechanism starts to engage (the time when the dog teeth come into contact) until the input rotational speed changes to the rotational speed corresponding to the gear ratio after the shift. Therefore, in the example shown in FIG. 2, first, the amount of change in rotational speed accompanying the shift and the shift time are stored (step S1). Specifically, the amount of change in the input-side rotating member (the rotating member connected to the driving force source) of the meshing engagement mechanism and the period thereof are stored from the time when the meshing engagement mechanism starts to engage (the time when the dog teeth come into contact) until the input rotational speed changes to the rotational speed corresponding to the gear ratio after the shift.

[0021] Subsequent to step S1, the impact torque T during the shift is estimated (step S2). Specifically, the impact torque is estimated based on the following equation (1). T = I × dω / dt …(1) In equation (1), I is the moment of inertia of the members connected to the input-side rotating member, including the driving force source and the input-side rotating member of the meshing engagement mechanism, and dω / dt is the angular acceleration of the input-side rotating member. The angular acceleration of the input-side rotating member can be obtained by dividing the amount of change in rotational speed stored in step S1 by the period. Here, since the impact load can be obtained by dividing the impact torque acting on one rotating member by a fixed value based on specifications such as the radius of the dog teeth and the number of meshing teeth, the impact torque is obtained in this control example.

[0022] Next, the cumulative damage D accumulated on the dog teeth is calculated (step S3). Here, the cumulative damage is calculated based on the Miner's rule. That is, an S-N curve determined in advance by experiments based on the shape and material of the dog teeth is stored in the ECU 1, the stress σ corresponding to the impact torque T estimated in step S2 is obtained, and the reciprocal of the number of fracture repetitions N corresponding to the stress σ is added to the cumulative damage stored in the ECU 1.

[0023] Figure 3 shows an S-N curve, with the stress σ (logarithmic) on the vertical axis and the number of fracture repetitions N (logarithmic) on the horizontal axis. Therefore, for example, if the stress corresponding to the collision torque T estimated in step S2 is σ1, the number of fracture repetitions corresponding to that stress σ1 is N1. In step S3, 1 / N1 is added to and updated the cumulative damage D stored in the ECU1. In addition, in order to consider the damage in the region where the stress is below σw as shown in Figure 3, the cumulative damage may be calculated based on the modified Miner's rule.

[0024] Then, it is determined whether or not the cumulative damage D calculated in step S3 is equal to or greater than the limit damage Dl (step S4). This limit damage Dl can be set to a value equal to or less than the damage at which the dog tooth fails due to fatigue.

[0025] If it is negatively determined in step S4 because the cumulative damage D is less than the limit damage Dl, this routine is terminated once as it is. On the contrary, if it is positively determined in step S4 because the cumulative damage D is equal to or greater than the limit damage Dl, a warning such as prompting the replacement of the meshing engagement mechanism (or transmission) is issued to the occupant (step S5), and this routine is terminated once. That is, a warning signal such as lighting (or flashing) an indicator lamp is output from the ECU1 to the warning device 7.

[0026] Estimate the impact torque acting on the dog tooth based on the rate of change of the input rotational speed (i.e., angular acceleration) associated with the shift as described above, and the moment of inertia of the member connected to the input-side rotating member, including the driving power source and the input-side rotating member of the meshing engagement mechanism. Then, obtain the cumulative damage D accumulated on the dog tooth based on the estimated impact torque and the number of fracture repetitions of the dog tooth corresponding to the impact torque. That is, the degree of influence of the damage accumulated on the dog tooth is determined according to the impact torque acting on the dog tooth. Therefore, even if the impact torque acting on the dog tooth during meshing varies for each meshing operation, the damage D accumulated on the dog tooth can be estimated according to the impact torque acting on the dog tooth for each meshing operation. Thus, the damage of the meshing engagement mechanism can be appropriately estimated.

Explanation of Signs

[0027] 1 Electronic control unit (ECU) 2 Transmission 3 Input shaft 4 Input rotational speed sensor 5 Output shaft 6 Output rotational speed sensor 7 Warning device

Claims

[Claim 1] A damage estimation device for a meshing engagement mechanism, comprising an input side rotating member and an output side rotating member which rotate relative to each other, a movable member which is one of the input side rotating member and the output side rotating member being configured to approach and move away from the other rotating member, and the input side rotating member and the output side rotating member being formed with dog teeth which mesh with each other when the movable member approaches the other rotating member, A controller for estimating damage to the meshing engagement mechanism, The controller: a collision torque acting on the dog teeth is estimated based on an angular acceleration of one of the input side rotating member and the output side rotating member, the rotation speed of which changes in accordance with meshing of the dog teeth, and a moment of inertia of a member that rotates integrally with the one of the input side rotating member and the output side rotating member; A cumulative damage accumulated in the dog tooth is calculated based on the estimated collision torque and the number of repeated breakages of the dog tooth corresponding to the collision torque. A damage estimation device for a meshing engagement mechanism.

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