Drive transmission device, construction machine, drive transmission method, and storage medium

Abstract

The present application provides a drive transmission device, a construction machine, a drive transmission method, and a storage medium. A drive transmission device according to one embodiment of the present application includes a pair of output shafts, a differential device (210), a clutch (250) (power transmission portion), and a control portion (280). The pair of output shafts are connected to a pair of speed reducers (230) disposed facing each other. The differential device (210) outputs a driving force input from a motor (200) to the pair of output shafts. The clutch (250) acts on the differential device (210) and can take either of a first state in which a difference in load between the pair of output shafts can be adjusted and a second state in which the pair of output shafts directly rotate by the driving force. The control portion (280) switches the state of the clutch (250) based on difference information related to a difference in rotation between the pair of speed reducers (230).

Description

Technical Field

[0001] This invention relates to a drive transmission device, construction machinery, drive transmission method, and computer-readable storage medium. Background Technology

[0002] Traditionally, construction machinery such as hydraulic excavators has been equipped with speed reducers. A hydraulic excavator, for example, includes a boom, a stick rotatably connected to the boom, and a bucket located at the opposite end of the stick, rotatably connected to it via a speed reducer. As a related technology, for example, a technique has been disclosed for an electric drive actuator in a power excavator that constitutes a work machine system using an electric linear actuator.

[0003] In such excavators, for example, if a speed reducer is installed only on one side of the connection between the bucket and the stick, a torque load is generated only on that side of the connection during excavation, making it prone to failure. Therefore, it is desirable to install speed reducers on both sides of the bucket.

[0004] However, when speed reducers are installed on both sides of the bucket, a slight misalignment occurs between the speed reducers during bucket movement, causing a deviation in the load applied to the output shaft of the speed reducers. Therefore, for example, a differential device can be installed to eliminate the deviation in the load applied to the output shaft.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 63-300131 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] However, in the case of a differential gear, the gears within the differential rotate and revolve for a very short period before power is evenly distributed to the left and right reducers. Afterward, the gears and the reducer carrier only revolve together. Therefore, power is continuously transmitted only between the gears within the differential gear. Consequently, in the prior art, there is a concern that the gears will wear easily, thus shortening the product lifespan.

[0010] This invention provides a drive transmission device, construction machinery, drive transmission method, and computer-readable storage medium capable of suppressing the shortening of the product life of differential devices.

[0011] Solution for solving the problem

[0012] (1) A drive transmission device according to one aspect of the present invention comprises: a pair of output shafts connected to a pair of gear reducers arranged in opposite directions; a differential device that outputs a driving force input from a drive source to the pair of output shafts; a power transmission unit that acts on the differential device and is capable of taking either a first state or a second state, the first state being a state in which the load difference between the pair of output shafts can be adjusted, and the second state being a state in which the pair of output shafts rotate directly by the driving force; and a control unit that switches the power transmission unit to the first state or the second state based on difference information related to the difference in rotation of the pair of gear reducers.

[0013] With this configuration, after eliminating the difference in load applied to a pair of output shafts through differential motion, the driving force input from the drive source to the differential can be transmitted to the output shaft not only through the gears within the differential but also directly to the output shaft. Therefore, power can be continuously transmitted between the gears of the differential, thereby suppressing gear wear.

[0014] (2) Alternatively, the difference information may be information representing the input torque from the drive source to the differential device.

[0015] (3) Alternatively, the difference information may be information representing the rotational speed input from the drive source to the differential device.

[0016] (4) Alternatively, the control unit may maintain the power transmission unit in the first state before the value represented by the difference information becomes the first threshold, and switch the power transmission unit to the second state when the value represented by the difference information becomes the first threshold.

[0017] (5) Alternatively, when the value represented by the difference information becomes a second threshold higher than the first threshold, the control unit switches the power transmission unit to the first state and then switches the power transmission unit to the second state.

[0018] (6) Alternatively, the difference information may be a value representing the difference in rotation related to the input to the pair of reducers, or a value representing the difference in rotation related to the output from the pair of reducers.

[0019] (7) Another aspect of the present invention relates to a construction machine comprising: a vehicle body; a movable member rotatably supported on the vehicle body; a drive transmission device for actuating the movable member; a drive source for generating a driving force; and a pair of reducers arranged opposite to each other. The drive transmission device comprises: a pair of output shafts connected to the pair of reducers; a differential device for outputting a driving force input from the drive source to the pair of output shafts; a power transmission unit acting on the differential device, capable of taking either a first state or a second state, the first state being a state capable of adjusting the load difference between the pair of output shafts, and the second state being a state in which the pair of output shafts rotate directly by the driving force; and a control unit that switches the power transmission unit to the first state or the second state based on difference information related to the difference in rotation of the pair of reducers.

[0020] With this configuration, after eliminating the difference in load applied to a pair of output shafts through differential motion, the driving force input from the drive source to the differential can be transmitted to the output shaft not only through the gears within the differential but also directly to the output shaft. Therefore, power can be continuously transmitted between the gears of the differential, thereby suppressing gear wear.

[0021] (8) Another aspect of the present invention relates to a drive transmission device comprising: a pair of output shafts connected to a pair of gearboxes arranged in opposite directions; a differential device that outputs a driving force input from a drive source to the pair of output shafts; a power transmission unit acting on the differential device, capable of taking either a first state or a second state, the first state being a state in which the load difference between the pair of output shafts can be adjusted, and the second state being a state in which the pair of output shafts rotate directly by the driving force; and a control unit that switches the power transmission unit to the first state or the second state based on difference information related to the difference in rotation of the pair of gearboxes. The control unit maintains the power transmission unit in the first state until the value represented by the difference information becomes a first threshold, and switches the power transmission unit to the second state when the value represented by the difference information becomes the first threshold.

[0022] With this configuration, when the load difference applied to a pair of output shafts is eliminated through differential motion when the drive source is started, the driving force input from the drive source to the differential can be transmitted to the output shaft not only through the gears within the differential but also directly to the output shaft. Therefore, power can be continuously transmitted between the gears of the differential, thereby suppressing gear wear.

[0023] (9) Another aspect of the present invention relates to a drive transmission method that causes a computer of a drive transmission device to perform processing, wherein the drive transmission device includes: a pair of output shafts connected to a pair of gear reducers arranged in opposite directions; a differential device that outputs a driving force input from a drive source to the pair of output shafts; and a power transmission unit that acts on the differential device and is capable of taking either a first state or a second state, the first state being a state in which the load difference between the pair of output shafts can be adjusted, and the second state being a state in which the pair of output shafts rotate directly by the driving force, wherein the drive transmission method causes the computer of the drive transmission device to perform the following processing: switching the power transmission unit to the first state or the second state based on difference information related to the difference in rotation of the pair of gear reducers.

[0024] (10) Another aspect of the present invention relates to a computer-readable storage medium storing a program that causes a computer of a drive transmission device to perform processing, wherein the drive transmission device comprises: a pair of output shafts connected to a pair of gear reducers arranged in opposite directions; a differential device that outputs a driving force input from a drive source to the pair of output shafts; and a power transmission unit that acts on the differential device and is capable of taking either a first state or a second state, the first state being a state in which the load difference between the pair of output shafts can be adjusted, and the second state being a state in which the pair of output shafts rotate directly by the driving force, the program causing the computer of the drive transmission device to perform the following processing: switching the power transmission unit to the first state or the second state based on difference information related to the difference in rotation of the pair of gear reducers.

[0025] The effects of the invention

[0026] Based on the aforementioned drive transmission device, construction machinery, drive transmission method, and computer-readable storage medium, it is possible to suppress the shortening of the product life of the differential device. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the excavator involved in the construction machinery, which is viewed from the side during the implementation of the method.

[0028] Figure 2 It shows the setting in Figure 1 The diagram shows a detailed structural diagram of the drive transmission device at the connection between the boom and the bucket.

[0029] Figure 3 It is shown Figure 2 The diagram shows a schematic structural diagram of the drive transmission device.

[0030] Figure 4 It is shown Figure 3 An explanatory diagram illustrating an example of the hardware structure of the control unit.

[0031] Figure 5 This is a flowchart illustrating an example of the drive transmission processing performed by the control unit according to the embodiment.

[0032] Figure 6 This is a flowchart illustrating an example of the drive transmission processing performed by the control unit involved in Modification Example 1.

[0033] Figure 7 This is a flowchart illustrating an example of the drive transmission processing performed by the control unit involved in Modification Example 3.

[0034] Explanation of reference numerals in the attached figures

[0035] 100: Excavator (construction machinery); 120: Drive transmission device; 200: Motor (drive source); 210: Differential device; 211: First bevel gear; 212: Second bevel gear; 213: Differential housing; 214: Pinion gear; 215: Side gear; 221a: First output shaft; 221b: Second output shaft; 230a: First reducer; 230b: Second reducer; 250: Clutch (power transmission unit); 280: Control unit. Detailed Implementation

[0036] Next, embodiments of the present invention will be described with reference to the accompanying drawings.

[0037] <Excavator>

[0038] Figure 1 This is a schematic structural diagram of the excavator 100 involved in the construction machinery, which is viewed from the side of the implementation method.

[0039] Furthermore, in the following description, the direction facing the operator of the excavator 100 (not shown) (the left direction in the figure) is defined as "forward". The horizontal direction opposite to "forward" is defined as "rear". The vertical direction in the figure is defined as the "vertical direction" of the excavator 100. The direction orthogonal to the forward / backward and vertical directions is referred to as the "vehicle width direction". Therefore, Figure 1 The image shows the state of the excavator 100 as viewed from the vehicle width direction.

[0040] like Figure 1 As shown, the excavator 100 includes a traveling body 101, a slewing mechanism 102, a slewing body 103, and an operating part 104. The traveling body 101, the slewing mechanism 102, and the slewing body 103 are examples of the machine body.

[0041] The traveling body 101 enables the excavator 100 to travel forward or backward. The traveling body 101 may, for example, have two tracks 105 arranged in the width direction. However, the traveling body 101 is not limited to having tracks 105; it may also have wheels. A slewing mechanism 102 is provided on the upper part of the traveling body 101. A slewing body 103 is provided on the upper part of the traveling body 101 and can rotate relative to the traveling body 101 via the slewing mechanism 102.

[0042] The action part 104 is provided on the rotating body 103. The action part 104 is an example of a movable member. The action part 104 includes a boom 108, a stick 109, and a bucket 110. The boom 108, stick 109, and bucket 110 are rotatably connected via a drive transmission device 120.

[0043] Specifically, one end of the boom 108 along its long side is rotatably connected to the slewing body 103. One end 109a of the stick 109 along its long side is rotatably connected to the other end 108a of the boom 108 along its long side via a drive transmission device 120. The bucket 110 is rotatably connected to the other end 109b of the stick 109 along its long side via the drive transmission device 120.

[0044] The drive transmission device 120 installed in each part can all be of the same structure. In addition, a drive transmission device 120 is also provided at the connection between the rotating body 103 and the boom 108.

[0045] In the following description, the drive transmission device 120 disposed between the other end 109b of the boom 109 in the long side direction and the bucket 110 is described, and the description of other drive transmission devices 120 is omitted.

[0046] Figure 2 This is a structural diagram showing details of the drive transmission device 120 at the connection between the boom 109 and the bucket 110. Figure 3 This is a structural diagram showing the outline of the drive transmission device 120.

[0047] like Figure 2 and Figure 3 As shown, the drive transmission device 120 includes a differential device 210, an output shaft 221, a clutch 250, and a control unit 280. The driving force of the motor 200 is input to the differential device 210. Specifically, the motor 200 is built into the stick 109. The motor 200 generates rotational force.

[0048] Motor 200 is an example of a drive source. Motor 200 is, for example, an electric motor that is driven by electricity supplied to an external power source (battery) provided in the rotating body 103. As motor 200, various motors that are driven by electricity, such as brushed motors and brushless motors, can be used. Furthermore, motor 200 is not limited to electric motors, but can also be a hydraulic motor.

[0049] The differential device 210 is connected to a pair of output shafts 221a and 221b. The pair of output shafts 221a and 221b are respectively connected to a pair of speed reducers 230a and 230b. The pair of speed reducers 230a and 230b have shafts that receive input rotational force and shafts that output rotational force. The shafts receiving input rotational force and the shafts outputting rotational force are arranged along the same axis of rotation C1. The pair of speed reducers 230a and 230b are arranged facing each other along the axis of rotation C1.

[0050] The differential device 210 performs differential motion. Differential motion is an action that can adjust (eliminate) the difference (deviation) in the load applied to the output shafts 221a and 221b.

[0051] Specifically, the differential 210 is housed within the housing 220. The differential 210 includes a first bevel gear 211, a second bevel gear 212, a differential case 213, a pinion 214, and side gears 215 (first side gear 215a and second side gear 215b).

[0052] When the motor 200 is driven, the motor shaft 200a rotates, and the transmission shaft 201 rotates as well. When the transmission shaft 201 rotates, its rotational force is transmitted to the first bevel gear 211. Consequently, the first bevel gear 211 rotates. When the first bevel gear 211 rotates, the second bevel gear 212, which meshes with it, rotates. When the second bevel gear 212 rotates, the differential housing 213 and the pinion 214, which are fixed to it, rotate. When the pinion 214 rotates, the side gears 215 (first side gear 215a, second side gear 215b) meshing with it rotate.

[0053] When the first side gear 215a rotates, the rotational force of the first side gear 215a is transmitted to the first reducer 230a via the first output shaft 221a. When the second side gear 215b rotates, the rotational force of the second side gear 215b is transmitted to the second reducer 230b via the second output shaft 221b.

[0054] The first reducer 230a rotates by rotating the first output shaft 221a. The second reducer 230b rotates by rotating the second output shaft 221b.

[0055] In this way, the rotation of the motor shaft 200a is transmitted to the two reducers 230a and 230b via the transmission shaft 201 and the differential device 210. The output of the two reducers 230a and 230b is transmitted to the bucket 110.

[0056] If differential motion is supplemented, the meshing timing of each part in the two reducers 230a and 230b may gradually differ due to minor manufacturing or assembly errors. Therefore, when the differential device 210 starts operating, the load applied to the output shafts 221a and 221b connected to the two reducers 230a and 230b may sometimes differ. In this case, each reducer 230a and 230b is driven under conditions of load deviation.

[0057] In this embodiment, the pinion 214 of the differential device 210 is rotatably supported by the differential housing 213. Therefore, when the loads applied to each output shaft 221a, 221b are different, the rotation of the pinion 214 eliminates the difference in loads applied to each output shaft 221a, 221b. Thus, the load is applied uniformly to each output shaft 221a, 221b, and in this state, the rotation of the transmission shaft 201 is transmitted to each reducer 230a, 230b.

[0058] The action of eliminating the difference (deviation) in the load applied to the output shafts 221a and 221b is called differential motion.

[0059] Furthermore, for a very short period before the power is evenly distributed to the left and right reducers 230a and 230b, the gear (e.g., pinion 214) in the differential device 210 rotates on its own axis, and then the gear and the differential housing 213 of the reducer 230 only revolve around the central axis.

[0060] At this time, for example, when the pinion 214 and the side gear 215 are meshed at the same position, and power is continuously transmitted only between the pinion 214 and the side gear 215, there is a concern that the pinion 214 and the side gear 215 may wear due to micro-vibration.

[0061] In this regard, the drive transmission device 120 according to this embodiment includes a clutch 250, which allows the driving force from the motor 200 to be directly transmitted from each output shaft 221a, 221b to the reducer 230.

[0062] (Regarding clutch 250)

[0063] Clutch 250 is an example of a power transmission unit. Clutch 250 is provided, for example, between differential 210 and reducer 230 (reducer 230a, 230b), and acts on differential 210 (e.g., to engage or disengage from differential 210).

[0064] The clutch 250 switches between an open state and an engaged state. Specifically, the open state (disengaged state: first state) of the clutch 250 is a state in which differential motion can be performed. More specifically, the open state of the clutch 250 is the state in which the second bevel gear 212 is separated from the power transmission unit 222. Therefore, in the open state of the clutch 250, the pinion 214 and the side gear 215 rotate together with the second bevel gear 212, thereby causing the output shaft 221 to rotate.

[0065] On the other hand, when the clutch 250 is engaged (contact state: second state), differential motion based on the differential device 210 does not occur. Specifically, when the clutch 250 is engaged, the output shaft 221 rotates together with the power transmission unit 222. Therefore, when the clutch 250 is engaged (contact state), the second bevel gear 212 is in contact with the power transmission unit 222, and the power transmission unit 222 rotates in response to the rotation of the second bevel gear 212. Thus, the rotational force of the second bevel gear 212 is directly transmitted to the output shaft 221.

[0066] Therefore, in the contact state, the output shaft 221 rotates through direct transmission from the second bevel gear 212 and transmission accompanying the rotation of the side gear 215.

[0067] The control unit 280 switches between the engaged and disengaged states of the clutch 250 based on difference information relating to the difference in rotation of the pair of reducers 230a and 230b. The difference information represents the difference in torque between the pair of reducers 230a and 230b. Alternatively, the difference information may also represent the difference in rotation of the pair of reducers 230a and 230b.

[0068] The difference in rotation between the pair of reducers 230a and 230b is related to information concerning the rotation input from motor 200 to differential 210. This information concerning the rotation input from motor 200 to differential 210 is the input torque. Furthermore, this information may also be the rotational speed.

[0069] Hereinafter, information related to the rotation input from the motor 200 to the differential device 210 will be described as input torque information, but the same applies if the information is speed information.

[0070] The correlation between the input torque and the difference in rotation between the pair of reducers 230a and 230b is specifically as follows: the greater the difference in rotation between the pair of reducers 230a and 230b, the greater the input torque input to the differential device 210.

[0071] Furthermore, the input torque input to the differential 210 is also related to the current value of the motor 200. Specifically, for example, the greater the input torque input to the differential 210, the greater the current value of the motor 200.

[0072] Therefore, it can be said that the difference in rotation between the pair of reducers 230a and 230b is also related to the current value of the motor 200. Therefore, in this embodiment, the difference information is information representing the current value of the motor 200. For example, the current value of the motor 200 can be obtained based on the command value of the motor 200.

[0073] In this embodiment, before the input torque input to the differential device 210 becomes a threshold value, the control unit 280 disengages the clutch 250 (disengaged state) to perform differential motion. Then, when the input torque becomes above the threshold value, the control unit 280 switches the clutch 250 to an engaged state (contact state) so that the driving force of the motor 200 is directly transmitted from each output shaft 221a, 221b to the reducer 230.

[0074] The threshold is, for example, a value that can be estimated as the absence of a deviation in the load applied to each output shaft 221a, 221b when the actuator 104 begins to operate. Specifically, the threshold is expressed as a proportion relative to the current value (100%) used to obtain the rated torque, for example, a value of 10% of the rated torque.

[0075] (Example of hardware structure for control unit 280)

[0076] Figure 4 This is an explanatory diagram showing an example of the hardware structure of the control unit 280. (As shown...) Figure 4 As shown, the control unit 280 includes an AD (analog-to-digital) converter 301, a RAM (random access memory) 302, a ROM (read-only memory) 303, a CPU (Central Processing Unit) 304, and a DA (digital-to-analog) converter 305.

[0077] The AD converter 301 converts analog signals from the operating unit, such as the analog signal and the current value of the motor 200, into digital signals. RAM 302 is a memory that stores threshold values ​​used in the control of clutch 250 engagement / disengagement, control values ​​of the motor 200, and various other data. ROM 303 stores the drive transmission program used to instruct CPU 304 to operate. CPU 304 sends out control signals for switching clutch 250 according to the drive transmission program stored in ROM 303. The DA converter 305 converts the control signals calculated by CPU 304 as digital values ​​into analog signals.

[0078] (An example of the drive transmission processing performed by the control unit 280 in the embodiment)

[0079] Figure 5 This is a flowchart illustrating an example of the drive transmission processing performed by the control unit 280 according to the embodiment. For example... Figure 5 As shown, the control unit 280 determines whether to start the rotation of the motor 200 (step S501). The control unit 280 remains in standby mode until the rotation of the motor 200 starts (step S501: "No"). When the rotation of the motor 200 starts (step S501: "Yes"), the input torque is detected based on the current value of the motor 200 (step S502).

[0080] The control unit 280 determines whether the input torque (current value of motor 200) is above a threshold (step S503). If the input torque is not above the threshold (step S503: "No"), the control unit 280 switches the clutch 250 to disengagement (disengagement state) (step S504), that is, switches to differential motion based on differential device 210, and proceeds to step S506. If the input torque is above the threshold (step S503: "Yes"), the control unit 280 switches the clutch 250 to engagement (contact state) (step S505). That is, the control unit 280 directly transmits the driving force of motor 200 from each output shaft 221a, 221b to reducer 230.

[0081] Then, the control unit 280 determines whether to stop the rotation of the motor 200 (step S506). If the rotation of the motor 200 is not stopped (step S506: "No"), the control unit 280 returns to step S502. If the rotation of the motor 200 is stopped (step S506: "Yes"), the control unit 280 ends the series of processes.

[0082] As explained above, the drive transmission device 120 of this embodiment switches between the disengaged and engaged states of the clutch 250 based on the difference information between the pair of reducers 230. Therefore, after eliminating the difference in load applied to the pair of output shafts 221 through the differential movement of the differential device 210, not only can the driving force input from the motor 200 to the differential device 210 be transmitted to the output shaft 221 along with the rotation of the side gear 215, but also the driving force can be transmitted directly to the output shaft 221 from the second bevel gear 212. Thus, power is not continuously transmitted only between the gears of the differential device 210 (e.g., between the pinion 241 and the side gear 215). Therefore, wear on the gears (e.g., the pinion 241 and the side gear 215) can be suppressed. Therefore, according to this embodiment, the shortening of the product life of the differential device 210 can be suppressed.

[0083] Furthermore, in this embodiment, the difference information is set to represent the input torque from the motor 200 to the differential device 210. Therefore, the difference information can be easily obtained even without additional sensors. Moreover, even when the difference information is set to represent the rotational speed from the motor 200 to the differential device 210, the difference information can still be easily obtained.

[0084] Furthermore, in this embodiment, the drive transmission device 120 switches the clutch 250 to an open state (disengaged state) before the value represented by the difference information becomes a threshold, and switches the clutch 250 to an engaged state (contact state) when the value represented by the difference information becomes the threshold. Therefore, when the drive of the motor 200 begins and the operation of the actuator 104 begins, the load difference applied to the pair of output shafts 221 can be eliminated through differential motion, and driving force can be directly output to the output shafts 221. Thus, after eliminating the load difference, power can be continuously transmitted between the gears of the differential device 210. This suppresses gear wear.

[0085] (Modifications of the implementation method)

[0086] Next, variations of the implementation method will be described. Furthermore, in the following variations, descriptions of the content explained in the above-described implementation method will be appropriately omitted. Additionally, the following variations and the above-described implementation method can be combined separately.

[0087] (Variation Example 1)

[0088] Modification 1 of the implementation method is explained. In the above implementation method, the switching of clutch 250 is controlled when the input torque of differential device 210 becomes a threshold value or higher. In Modification 1, in addition to this structure, the switching of clutch 250 is also controlled when the input torque becomes a second threshold value or higher than the threshold value (hereinafter referred to as "first threshold value").

[0089] In Modification 1, when the value represented by the difference information becomes a second threshold higher than the first threshold, the control unit 280 switches the clutch 250 to the disengaged state (disconnected state) and then returns the clutch 250 to the engaged state (contacted state).

[0090] The second threshold is a value estimated based on the internal torsional stiffness of the reducers 230a and 230b as a deviation from the fixed amount of load applied to each output shaft 221a and 221b.

[0091] The first threshold is, for example, 10% of the current value used to obtain the rated torque. The second threshold is, for example, 40% of the current value used to obtain the rated torque. Furthermore, the first and second thresholds can be set to arbitrary values.

[0092] (An example of the drive transmission processing performed by the control unit 280 involved in Modification 1)

[0093] Figure 6 This is a flowchart illustrating an example of the drive transmission processing performed by the control unit 280 involved in Modification 1. For example... Figure 6 As shown, the control unit 280 determines whether to start the rotation of the motor 200 (step S601). The control unit 280 remains in standby mode until the rotation of the motor 200 starts (step S601: "No"). When the rotation of the motor 200 starts (step S601: "Yes"), the input torque is detected based on the current value of the motor 200 (step S602).

[0094] Then, the control unit 280 determines whether the input torque (current value of motor 200) is above a first threshold (step S603). If the input torque is not above the first threshold (step S603: "No"), the control unit 280 switches the clutch 250 to the disengaged state (disengaged state) (step S604), that is, switches to differential motion based on differential device 210, and proceeds to step S609. Thus, when the drive of motor 200 starts and the operation of actuator 104 starts, the load deviation applied to each output shaft 221a, 221b can be eliminated by differential motion.

[0095] When the input torque is above the first threshold (step S603: "Yes"), the control unit 280 switches the clutch 250 to the engagement state (contact state) (step S605). That is, the control unit 280 causes the driving force of the motor 200 to be directly transmitted from each output shaft 221a, 221b to the reducer 230. As a result, after there is no longer any deviation in the load applied to each output shaft 221a, 221b, each output shaft 221a, 221b rotates through direct transmission from the second bevel gear 212 and transmission accompanying the rotation of the side gear 215.

[0096] Then, the control unit 280 determines whether the input torque (the current value of the motor 200) is above the second threshold (step S606). If the input torque is not above the second threshold (step S606: "No"), the control unit 280 proceeds to step S609. If the input torque is above the second threshold (step S606: "Yes"), the control unit 280 switches the clutch 250 to the disengaged state (disengaged state) (step S607). That is, the control unit 280 causes differential motion based on the differential device 210 to be performed. As a result, even if a deviation in the load applied to each output shaft 221a, 221b occurs due to the torsional stiffness inside the reducers 230a, 230b, the deviation can be eliminated.

[0097] Next, the control unit 280 switches the clutch 250 back to the engaged state (contact state) (step S608). That is, the control unit 280 causes the driving force of the motor 200 to be directly transmitted from each output shaft 221a, 221b to the reducer 230. Then, the control unit 280 determines whether to stop the rotation of the motor 200 (step S609). If the rotation of the motor 200 is not stopped (step S609: "No"), the control unit 280 returns to step S602. If the rotation of the motor 200 is stopped (step S609: "Yes"), the control unit 280 ends the series of processes.

[0098] In the modified example 1 described above, when the value represented by the difference information becomes the second threshold, the drive transmission device 120 switches the clutch 250 to the disengaged state, thereby enabling the differential device 210 to perform differential motion. Thus, even if a load deviation occurs on the two output shafts 221 corresponding to the difference in torsional stiffness within the reducer 230, the deviation can be eliminated by the differential motion of the differential device 210.

[0099] Furthermore, the drive transmission device 120 then switches the clutch 250 into an engaged state, allowing the drive force input from the motor 200 to the differential 210 to be directly transmitted to the output shaft 221. This enables each output shaft 221 to rotate via direct transmission from the second bevel gear 212 and transmission accompanying the rotation of the side gear 215. Therefore, power is not continuously transmitted only between the gears of the differential 210 (e.g., between the pinion 241 and the side gear 215). Consequently, wear on the gears (e.g., the pinion 241 and the side gear 215) can be suppressed, and the product life of the differential 210 can be prevented from being shortened.

[0100] (Variation Example 2)

[0101] Next, a variation of the embodiment will be described. In the above embodiment, the difference information is set to represent the input torque input to the differential device 210. In variation 2, the case in which the difference information is set to represent the output torque (that is, the torque input to the reducers 230a and 230b) output from the differential device 210 toward the reducers 230a and 230b will be described.

[0102] The output torque is the sum of the two torques output from the differential device 210 to the two reducers 230a and 230b. The output torque is detected by a torque sensor.

[0103] The control unit 280 controls the switching of the clutch 250 based on the output torque and a threshold. Specifically, when the output torque becomes higher than the threshold, the control unit 280 controls the switching of the clutch 250. More specifically, before the output torque becomes higher than the threshold, the control unit 280 keeps the clutch 250 in an open state (disengaged state) to allow differential movement based on the differential device 210 to occur. On the other hand, when the output torque becomes higher than the threshold, the control unit 280 switches the clutch 250 to an engaged state (contact state) so that the driving force input from the motor 200 to the differential device 210 is directly transmitted to the output shaft 221.

[0104] In Modification 2, the clutch 250 is switched between engaged and disengaged states based on the output torque from the differential 210 to the reducers 230a and 230b. Even with this configuration, power is not continuously transmitted only between the gears of the differential 210 (e.g., between the pinion 241 and the lateral gear 215). Therefore, wear on the gears (e.g., the pinion 241 and the lateral gear 215) can be suppressed.

[0105] (Variation Example 3)

[0106] Next, a variation of the embodiment, 3, will be described. In variation 2 described above, the difference information is set as the sum of the two torques output from the differential device 210 to the two reducers 230a and 230b. In variation 3, the case in which the difference information is set as a value representing the difference in rotation related to the output of the pair of reducers 230a and 230b will be described.

[0107] Specifically, in Variation 3, the value representing the difference in rotational speed related to the output is, for example, the difference in output values ​​from the two reducers 230a and 230b. The output value is, for example, the output torque output from the pair of reducers 230a and 230b. However, the output value could also be the rotational speed output from the pair of reducers 230a and 230b.

[0108] The difference information could also be, for example, a value representing the difference in rotational speed related to the input of a pair of reducers 230a and 230b. The value representing the difference in rotational speed related to the input is the difference in the input values ​​input to the two reducers 230a and 230b. The input value could be, for example, the input torque input to the pair of reducers 230a and 230b. However, the input value could also be the rotational speed input to the pair of reducers 230a and 230b.

[0109] Torque is detected using a torque sensor. Rotational speed is detected using a rotation sensor.

[0110] (An example of the drive transmission processing performed by the control unit 280 involved in Modification 3)

[0111] Figure 7 This is a flowchart illustrating an example of the drive transmission processing performed by the control unit 280 involved in Modification Example 3. For example... Figure 7 As shown, the control unit 280 determines whether to start the rotation of the motor 200 (step S701). The control unit 280 remains in standby mode until the rotation of the motor 200 starts (step S701: "No"). When the rotation of the motor 200 starts (step S701: "Yes"), the output difference of the output torques output by the pair of reducers 230a and 230b is detected using the detection result detected by the torque sensor (step S702).

[0112] Then, the control unit 280 determines whether the output difference is below a threshold (step S703). An output difference below the threshold means that it is estimated that no deviation of the load applied to each output shaft 221a, 221b has occurred. If the output difference is below the threshold (step S703: "Yes"), that is, if it can be estimated that no deviation of the load applied to each output shaft 221a, 221b has occurred, the control unit 280 switches the clutch 250 to the engagement state (contact state) (step S704), that is, switches to allow the driving force of the motor 200 to be directly transmitted from each output shaft 221a, 221b to the reducer 230, and proceeds to step S706.

[0113] If the output difference is not below a threshold (step S703: "No"), that is, if it can be estimated that a deviation in the load applied to each output shaft 221a, 221b has occurred, the control unit 280 switches the clutch 250 to the disengaged state (disengaged state) (step S705). That is, the control unit 280 causes differential movement based on the differential device 210 to occur. As a result, the output difference of the output torques output by the pair of reducers 230a, 230b can be reduced (becoming below a threshold).

[0114] That is, in the event of a deviation in the load applied to each output shaft 221a, 221b, the deviation can be eliminated whenever it occurs. Moreover, in subsequent processing, the process can be transferred from step S703 (“Yes”) to step S704. Therefore, the driving force of the motor 200 can be directly transmitted from each output shaft 221a, 221b to the reducer 230.

[0115] Then, the control unit 280 determines whether to stop the rotation of the motor 200 (step S706). If the rotation of the motor 200 is not stopped (step S706: "No"), the control unit 280 returns to step S702. If the rotation of the motor 200 is stopped (step S706: "Yes"), the control unit 280 ends the series of processes.

[0116] According to Variation 3, whenever the difference in output torque from a pair of reducers 230 exceeds a threshold, i.e., whenever a deviation is estimated to have caused a load applied to each output shaft 221, the deviation can be eliminated. Then, after eliminating the deviation, not only can the driving force input from the motor 200 to the differential 210 be transmitted to the output shaft 221 along with the rotation of the side gear 215, but the driving force can also be transmitted directly to the output shaft 221 from the second bevel gear 212. Therefore, power is not continuously transmitted only between the gears of the differential 210 (e.g., between the pinion 241 and the side gear 215). Thus, wear on the gears (e.g., the pinion 241 and the side gear 215) can be suppressed.

[0117] (Variation Example 4)

[0118] Next, a variation of the embodiment 4 will be described. In the above embodiment, the structure is configured to directly obtain the difference information based on information representing the input torque input to the differential device 210. In variation 4, the case where the difference information is set as time information obtained from a timer will be described.

[0119] In Variation 4, the relationship between time and torque is assumed to be known in advance. That is, it is assumed that the time information obtained from the timer corresponds to the information representing the input torque. More specifically, for example, it is assumed that for each action performed by the actuator 104, the relationship between time and torque corresponds, for example, the input torque at time t0 is T0, and the input torque at time t1 is T1. The control unit 280 controls the switching of the clutch 250 based on the time information.

[0120] Specifically, when the output torque is estimated to be above a threshold value (first time), the control unit 280 controls the switching of the clutch 250. More specifically, before the first time occurs, the control unit 280 keeps the clutch 250 in an open state (disengaged state) to enable differential movement based on the differential device 210. On the other hand, when the first time occurs, the control unit 280 switches the clutch 250 to an engaged state (contact state) so that the driving force of the motor 200 is directly transmitted from each output shaft 221a, 221b to the reducer 230.

[0121] When the time (second time) at which the load deviation applied to each output shaft 221a, 221b is caused by the torsional stiffness inside the reducers 230a, 230b is known, the control unit 280 switches the clutch 250 to the disengaged state (disengaged state) when the second time occurs. That is, the control unit 280 causes differential movement based on the differential device 210 to be performed. Thus, even if the load deviation applied to each output shaft 221a, 221b is caused by the torsional stiffness inside the reducers 230a, 230b, the deviation can be eliminated based on the timer information. Furthermore, the control unit 280 then switches the clutch 250 back to the engaged state (contact state).

[0122] In variation 4, the clutch 250 is switched to an engaged or disengaged state based on time information obtained from a timer. Even with this structure, power is not continuously transmitted only between the gears of the differential 210 (e.g., between the pinion 241 and the side gear 215). Therefore, wear on the gears (e.g., the pinion 241 and the side gear 215) can be suppressed.

[0123] (Variation Example 5)

[0124] Next, a variation of the embodiment, 5, will be described. In variation 3 described above, the difference information is set to a value representing the difference in rotation related to the output from a pair of reducers 230a and 230b. In variation 5, the case where the difference information is set to represent the rotation value of one of the pair of reducers 230a and 230b will be described.

[0125] In Variation 5, the value representing the rotation of one of the pair of reducers 230a and 230b is, for example, the output value of one of the two reducers 230a and 230b. The output value is, for example, the output torque output from one reducer 230. However, the output value could also be the rotational speed output from one reducer 230.

[0126] Furthermore, the value representing the rotation of one of the pair of reducers 230a and 230b can, for example, be the input value of one of the two reducers 230a and 230b. The input value is, for example, the input torque of the reducer 230 input to one of them. However, the input value can also be the rotational speed of the reducer 230 input to one of them.

[0127] Before the output value of one of the two reducers 230a and 230b becomes a threshold value, the control unit 280 keeps the clutch 250 in an open state (disengaged state) to enable differential motion based on the differential device 210. On the other hand, when the output value becomes a threshold value, the control unit 280 switches the clutch 250 to an engaged state (contact state) so that the driving force of the motor 200 is directly transmitted from each output shaft 221a and 221b to the reducer 230.

[0128] In Modification 5, the clutch 250 is switched between engaged and disengaged states based on a value representing the rotation of one of the pair of reducers 230a and 230b. Even with this configuration, power is not continuously transmitted only between the gears of the differential 210 (e.g., between pinion 241 and side gear 215). Therefore, wear on the gears (e.g., pinion 241 and side gear 215) can be suppressed.

[0129] Alternatively, the program for implementing the drive transmission device 120 described above can be recorded on a computer-readable recording medium, so that the computer system can read and execute the program.

[0130] Furthermore, the term "computer system" as used here refers to hardware including the operating system and peripheral devices. Additionally, "computer-readable recording media" refers to removable media such as floppy disks, optical disks, ROMs, and CD-ROMs, as well as storage devices such as hard drives built into the computer system. Moreover, "computer-readable recording media" also includes media that retain programs for a certain period of time, such as volatile memory (RAM) within a computer system that acts as a server or client when programs are transmitted via networks such as the Internet or communication lines such as telephone lines.

[0131] The aforementioned program can also be transmitted from a computer system storing the program in a storage device or the like to other computer systems via a transmission medium or by transmission waves in the transmission medium. The "transmission medium" used to transmit the program refers to a medium with the function of transmitting information, such as a network (communication network) like the Internet or a communication line (communication line) like a telephone line. Furthermore, the aforementioned program can also be used to implement a portion of the aforementioned functions. It can also be a so-called "difference file" (difference program) that can achieve the aforementioned functions by combining with a program already recorded in the computer system.

[0132] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the specific structure is not limited to these embodiments and may also include designs that do not depart from the spirit of the present invention.

[0133] In the embodiments and variations disclosed in this specification, the case where multiple functions are distributed can also be a case where some or all of the multiple functions are integrated; conversely, the case where multiple functions are integrated can be a case where some or all of the multiple functions are distributed. Whether the functions are integrated or distributed, it is acceptable as long as the configuration achieves the purpose of the invention.

Claims

1. A drive transmission device, comprising: A pair of output shafts, the pair of output shafts being connected to a pair of speed reducers arranged in opposite directions; A differential device that outputs the driving force input from the drive source to the pair of output shafts; The power transmission unit, acting on the differential device, is capable of taking on either a first state or a second state. The first state is a state in which the load difference between the pair of output shafts can be adjusted, and the second state is a state in which the pair of output shafts rotate directly by the driving force. The control unit switches the power transmission unit to the first state or the second state based on difference information related to the difference in rotation of the pair of reducers. in, The control unit maintains the power transmission unit in the first state until the value represented by the difference information becomes the first threshold, and switches the power transmission unit to the second state when the value represented by the difference information becomes the first threshold.

2. The drive transmission device according to claim 1, wherein, The difference information represents the input torque from the drive source to the differential device.

3. The drive transmission device according to claim 1, wherein, The difference information is information representing the rotational speed input from the drive source to the differential device.

4. The drive transmission device according to claim 1, wherein, When the value represented by the difference information becomes a second threshold higher than the first threshold, the control unit switches the power transmission unit to the first state, and then switches the power transmission unit to the second state.

5. The drive transmission device according to claim 1, wherein, The difference information represents a value indicating the difference in rotation related to the input to the pair of reducers, or a value indicating the difference in rotation related to the output from the pair of reducers.

6. A type of construction machinery, comprising: Body; Movable components that are rotatably supported on the vehicle body; A drive transmission device for causing the movable component to move; The driving source, which generates the driving force; and A pair of speed reducers, the pair of speed reducers being arranged facing each other. The drive transmission device includes: A pair of output shafts, the pair of output shafts being connected to the pair of speed reducers; A differential device that outputs the driving force input from the drive source to the pair of output shafts; The power transmission unit, acting on the differential device, is capable of taking on either a first state or a second state. The first state is a state in which the load difference between the pair of output shafts can be adjusted, and the second state is a state in which the pair of output shafts rotate directly by the driving force. The control unit switches the power transmission unit to the first state or the second state based on difference information related to the difference in rotation of the pair of reducers. The control unit maintains the power transmission unit in the first state until the value represented by the difference information becomes the first threshold, and switches the power transmission unit to the second state when the value represented by the difference information becomes the first threshold.

7. A drive transmission method, which enables a computer of the drive transmission device to perform processing. in, The drive transmission device includes: A pair of output shafts, the pair of output shafts being connected to a pair of speed reducers arranged in opposite directions; A differential device that outputs the driving force input from the drive source to the pair of output shafts; as well as The power transmission unit, acting on the differential device, is capable of taking on either a first state or a second state. The first state allows adjustment of the load difference between the pair of output shafts, while the second state allows the pair of output shafts to rotate directly via the driving force. The drive transmission method causes the computer of the drive transmission device to perform the following processes: Based on difference information relating to the difference in rotation of the pair of reducers, the power transmission unit is switched to either the first state or the second state; and The power transmission unit is kept in the first state until the value represented by the difference information becomes the first threshold, and the power transmission unit is switched to the second state when the value represented by the difference information becomes the first threshold.

8. A computer-readable storage medium storing a program that causes a computer driving a transmission device to perform processing. in, The drive transmission device includes: A pair of output shafts, the pair of output shafts being connected to a pair of speed reducers arranged in opposite directions; A differential device that outputs the driving force input from the drive source to the pair of output shafts; as well as The power transmission unit, acting on the differential device, is capable of taking on either a first state or a second state. The first state allows adjustment of the load difference between the pair of output shafts, while the second state allows the pair of output shafts to rotate directly via the driving force. The program causes the computer of the drive transmission device to perform the following processes: Based on difference information relating to the difference in rotation of the pair of reducers, the power transmission unit is switched to either the first state or the second state; and The power transmission unit is kept in the first state until the value represented by the difference information becomes the first threshold, and the power transmission unit is switched to the second state when the value represented by the difference information becomes the first threshold.

9. A computer program product comprising a computer program that, when executed by a computer, implements the drive delivery method of claim 7.

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