Drive transmission device, construction machine, drive transmission method, and program

Abstract

To provide a drive transmission device capable of suppressing the shortening of the product life of a differential device, a construction machine, a drive transmission method, and a program.SOLUTION: A drive transmission device includes a pair of output shafts, a differential device 210, clutches 250 (power transmission parts), and a control part 280. The pair of output shafts are connected to a pair of speed reducers 230 disposed facing each other. The differential device 210 outputs driving force inputted from a motor 200 to the pair of output shafts. The clutches 250 act on the differential device 210 to be able to take either one state of a first state for adjusting a load difference between the pair of output shafts and a second state for directly rotating the pair of output shafts by the driving force. The control part 280 switches states of the clutches 250 on the basis of difference information on a rotation difference between the pair of speed reducers 230.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a drive transmission device, a construction machine, a drive transmission method, and a program. [Background technology]

[0002] Conventionally, construction machines such as hydraulic excavators are equipped with speed reducers. A hydraulic excavator includes, for example, a boom, an arm rotatably connected to the boom, and a bucket rotatably connected via a speed reducer to the other end of the arm opposite the boom. A related technique has been disclosed in which an electric linear actuator is used as an electric drive actuator for a work machine system in a power excavator.

[0003] If the reducer were located on only one side of the bucket connection, the moment load would be generated on only one side during excavation, making it more susceptible to failure. For this reason, it is desirable to locate the reducers on both sides of the bucket. If the reducers were located on both sides of the bucket, slight misalignment would occur between the reducers on both sides during bucket operation, resulting in an uneven load on the output shaft. Therefore, by providing a differential, it is possible to eliminate the uneven load on both output shafts. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 63-300131 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the differential, the gears in the differential rotate and revolve for a short time until the power is evenly distributed to the left and right reducers, and then they only revolve together with the reducer carrier, so power continues to be transmitted only between the gears in the differential. For this reason, with the conventional technology, there was a problem that the gears were prone to wear and could have a shortened product lifespan.

[0006] The present invention provides a drive transmission device, a construction machine, a drive transmission method, and a program that can suppress a shortening of the product life of a differential device. [Means for solving the problem]

[0007] A drive transmission device according to one aspect of the present invention comprises: A drive transmission device that controls transmission of a drive force at any one of a plurality of connection parts, including a connection part that connects a vehicle body and a boom, a connection part that connects the boom and an arm, and a connection part that connects the arm and a bucket, A pair of output shafts connected to a pair of reducers arranged opposite each other, and a The aforementioned The device comprises a differential device that outputs a driving force to the pair of output shafts, a power transmission unit that acts on the differential device to take either a first state in which the difference in load between the pair of output shafts is adjusted, or a second state in which the pair of output shafts are directly rotated by the driving force, and a control unit that switches the state of the power transmission unit based on difference information regarding the difference in rotation in the pair of reducers.

[0008] With this configuration, after the difference in loads on the pair of output shafts is resolved by differential motion, the driving force input from the drive source to the differential device can be transmitted to the output shafts not only through the gears in the differential device but also directly to the output shafts, thereby preventing power from being continuously transmitted only between the gears of the differential device and reducing wear on the gears.

[0009] In the above configuration, the difference information may be information indicating an input torque input from the drive source to the differential device.

[0010] In the above configuration, the difference information may be information indicating the number of rotations input from the drive source to the differential device.

[0011] In the above configuration, the control unit may be configured to maintain the first state until the value indicated by the difference information reaches a first threshold, and to switch the state to the second state when the value reaches the first threshold.

[0012] In the above configuration, when the value indicated by the difference information becomes a second threshold value higher than the first threshold value, the first state may be entered, and then the state may be switched to the second state.

[0013] In the above configuration, the difference information may be a value indicating a difference in rotation regarding inputs to the pair of reducers, or a value indicating a difference in rotation regarding outputs from the pair of reducers.

[0014] A construction machine according to another aspect of the present invention includes a vehicle body and a connecting portion connecting the boom to the bucket, a connecting portion connecting the boom to the arm, and a connecting portion connecting the arm to the bucket. and, In the plurality of connecting portions a driving source that generates a driving force; A control relating to the transmission of the driving force at any one of the plurality of connecting portions is performed. a pair of output shafts connected to the pair of reducers, and a pair of drive shafts connected to the pair of reducers. The aforementioned The device comprises a differential device that outputs a driving force to the pair of output shafts, a power transmission unit that acts on the differential device to take either a first state in which the difference in load between the pair of output shafts is adjusted, or a second state in which the pair of output shafts are directly rotated by the driving force, and a control unit that switches the state of the power transmission unit based on difference information regarding the difference in rotation in the pair of reducers.

[0015] With this configuration, after the difference in loads on the pair of output shafts is resolved by differential motion, the driving force input from the drive source to the differential device can be transmitted to the output shafts not only through the gears in the differential device but also directly to the output shafts, thereby preventing power from being continuously transmitted only between the gears of the differential device and reducing wear on the gears.

[0016] A drive transmission device according to another aspect of the present invention comprises: A drive transmission device that controls transmission of a drive force at any one of a plurality of connection parts, including a connection part that connects a vehicle body and a boom, a connection part that connects the boom and an arm, and a connection part that connects the arm and a bucket, A pair of output shafts connected to a pair of reducers arranged opposite each other, and a The aforementioned The power transmission system includes a differential device that outputs driving force to the pair of output shafts, a power transmission unit that acts on the differential device to take one of a first state in which the difference in load between the pair of output shafts is adjusted, and a second state in which the pair of output shafts are directly rotated by the driving force, and a control unit that switches the state of the power transmission unit based on difference information regarding the difference in rotation in the pair of reducers, wherein the control unit keeps the power transmission unit in the first state until the value indicated by the difference information reaches a first threshold, and switches the state to the second state when the value indicated by the difference information reaches the first threshold.

[0017] With this configuration, when the drive source starts to drive and the difference in loads on the pair of output shafts due to differential motion is eliminated, the drive force input from the drive source to the differential device can be transmitted to the output shafts not only via the gears in the differential device but also directly to the output shafts, thereby preventing power from being continuously transmitted only between the gears of the differential device and thereby reducing wear on the gears.

[0018] A drive transmission method according to another aspect of the present invention includes a power transmission unit including a pair of output shafts connected to a pair of reducers arranged opposite to each other, a differential gear that outputs a drive force input from a drive source to the pair of output shafts, and a power transmission unit that can be in either a first state in which a load difference between the pair of output shafts is adjusted by acting on the differential gear, or a second state in which the pair of output shafts are directly rotated by the drive force. The control unit 100 controls the transmission of the driving force at any one of a plurality of connecting parts, including a connecting part that connects the vehicle body and the boom, a connecting part that connects the boom and the arm, and a connecting part that connects the arm and the bucket. A computer of the drive transmission device executes a process of switching the state of the power transmission section based on difference information relating to the difference in rotation between the pair of reducers.

[0019] A program according to another aspect of the present invention includes a power transmission unit including a pair of output shafts connected to a pair of reducers arranged opposite to each other, a differential gear that outputs a driving force input from a driving source to the pair of output shafts, and a power transmission unit that can be in either a first state in which a load difference between the pair of output shafts is adjusted by acting on the differential gear, or a second state in which the pair of output shafts are directly rotated by the driving force. The control unit 100 controls the transmission of the driving force at any one of a plurality of connecting parts, including a connecting part that connects the vehicle body and the boom, a connecting part that connects the boom and the arm, and a connecting part that connects the arm and the bucket. The computer of the drive transmission device is caused to execute processing to switch the state of the power transmission section based on difference information relating to the difference in rotation between the pair of reducers. [Effects of the Invention]

[0020] The above-described drive transmission device, construction machine, drive transmission method, and program can prevent a shortening of the product life of the differential device. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic configuration diagram of a shovel 100 according to an embodiment of the construction machine, as viewed from the side; [Figure 2] FIG. 3 is a configuration diagram showing details of a drive transmission device 120 at a connection portion between an arm 109 and a bucket 110. [Figure 3] FIG. 2 is a diagram showing the outline of a drive transmission device 120. [Figure 4] FIG. 2 is an explanatory diagram showing an example of the hardware configuration of a control unit 280. [Figure 5] 10 is a flowchart showing an example of a drive transmission process performed by a control unit 280 according to the embodiment. [Figure 6] 10 is a flowchart showing an example of a drive transmission process performed by a control unit 280 according to a first modification. [Figure 7] 10 is a flowchart showing an example of a drive transmission process performed by a control unit 280 according to a third modification. DETAILED DESCRIPTION OF THE INVENTION

[0022] Next, an embodiment of the present invention will be described with reference to the drawings.

[0023] <Shovel> FIG. 1 is a schematic diagram of a shovel 100 according to an embodiment of the construction machine, viewed from the side. In the following description, the direction in which an operator (not shown) operating the shovel 100 faces (to the left in the drawing) is referred to as "forward." The horizontal direction opposite to forward is referred to as "rearward." The up-down direction in the drawing is referred to as the "up-down direction" of the shovel 100. The direction perpendicular to the fore-and-aft direction and the up-and-down direction is referred to as the "vehicle width direction." FIG. 1 shows the shovel 100 as viewed from the vehicle width direction.

[0024] As shown in FIG. 1 , the excavator 100 includes a running body 101, a swivel mechanism 102, a rotating body 103, and an action unit 104. The running body 101, the swivel mechanism 102, and the rotating body 103 are examples of a vehicle body. The running body 101 causes the excavator 100 to travel forward or backward. The running body 101 includes, for example, two caterpillar tracks 105 arranged in the vehicle width direction. However, the running body 101 is not limited to including the caterpillar tracks 105, and may include wheels. The swivel mechanism 102 is provided on top of the running body 101. The swivel 103 is provided on top of the running body 101, and can be rotated relative to the running body 101 by the swivel mechanism 102.

[0025] The acting unit 104 is provided on the revolving unit 103. The acting unit 104 is an example of a movable member. The acting unit 104 includes a boom 108, an arm 109, and a bucket 110. The boom 108, the arm 109, and the bucket 110 are rotatably connected to each other via a drive transmission device 120. Specifically, one longitudinal end of the boom 108 is rotatably connected to the revolving unit 103. Furthermore, one longitudinal end 109a of the arm 109 is rotatably connected to the other longitudinal end 108a of the boom 108 via the drive transmission device 120. The bucket 110 is rotatably connected to the other longitudinal end 109b of the arm 109 via the drive transmission device 120.

[0026] The drive transmission devices 120 provided in each section can all have the same configuration. Note that a drive transmission device 120 is also provided at the connection between the revolving unit 103 and the boom 108. In the following explanation, the drive transmission device 120 that connects the bucket 110 to the other longitudinal end 109b of the arm 109 will be explained, and explanations of the other drive transmission devices 120 will be omitted.

[0027] FIG. 2 is a configuration diagram showing details of the drive transmission device 120 at the connection portion between the arm 109 and the bucket 110. FIG. 3 is a configuration diagram showing an outline of the drive transmission device 120. As shown in FIGS. 2 and 3, the drive transmission device 120 includes a differential device 210, an output shaft 221, a clutch 250, and a control unit 280. The drive force of a motor 200 is input to the differential device 210. More specifically, the motor 200 is built into the arm 109. The motor 200 generates a rotational force.

[0028] The motor 200 is an example of a drive source. The motor 200 is, for example, a so-called electric motor that is driven by a supply of electric power from an external power source (battery) provided on the revolving body 103. As the motor 200, various motors that are driven by a supply of electric power, such as a so-called brushed motor or brushless motor, can be used. Furthermore, the motor 200 is not limited to an electric motor, and may be a hydraulic motor.

[0029] Moreover, the differential gear 210 is connected to a pair of output shafts 221a, 221b. The pair of output shafts 221a, 221b are connected to a pair of reducers 230a, 230b, respectively. The pair of reducers 230a, 230b are arranged such that the shaft to which rotational force is input and the shaft to which rotational force is output are aligned along the same rotation axis C1, and are disposed opposite each other along the rotation axis C1.

[0030] The differential device 210 performs differential motion. The differential motion is an operation that adjusts (eliminates) the difference (bias) in the loads applied to the output shafts 221a and 221b. Specifically, the differential device 210 is housed in a housing 220. The differential device 210 includes a first bevel gear 211, a second bevel gear 212, a differential case 213, a pinion gear 214, and side gears 215 (first side gear 215a, second side gear 215b).

[0031] When the motor 200 is driven, the motor shaft 200a rotates, and the transmission shaft 201 rotates. When the transmission shaft 201 rotates, the rotational force is transmitted to the first bevel gear 211, causing the first bevel gear 211 to rotate. When the first bevel gear 211 rotates, the second bevel gear 212 meshing with the first bevel gear 211 rotates. Furthermore, when the second bevel gear 212 rotates, the differential case 213 fixed to the second bevel gear 212 and the pinion gear 214 rotate. When the pinion gear 214 rotates, a pair of side gears 215 meshing with the pinion gear 214 rotate.

[0032] When the first side gear 215a rotates, the rotational force is transmitted to the first reducer 230a via the first output shaft 221a. When the second side gear 215b rotates, the rotational force is transmitted to the second reducer 230b via the second output shaft 221b.

[0033] The first reducer 230a rotates due to the rotation of the first output shaft 221a. The second reducer 230b rotates due to the rotation of the second output shaft 221b. In this way, the rotation of the motor shaft 200a is transmitted to the two reducers 230a, 230b via the transmission shaft 201 and the differential gear 210. The outputs of these two reducers 230a, 230b are transmitted to the bucket 110.

[0034] Regarding the differential motion, the timing at which the two reducers 230a, 230b mesh may differ due to slight errors in the formation or assembly of the components. Therefore, when the differential device 210 first starts, the loads acting on the output shafts 221a, 221b connected to the two reducers 230a, 230b may differ. In such cases, the reducers 230a, 230b are driven with the loads unevenly distributed.

[0035] Here, the pinion gear 214 of the differential device 210 is rotatably supported by the differential case 213. Therefore, when the loads applied to the output shafts 221a, 221b are different, the difference in the loads applied to the output shafts 221a, 221b is eliminated by rotating the pinion gear 214. After this, the load is applied uniformly to the output shafts 221a, 221b, and in this state, the rotation of the transmission shaft 201 is transmitted to the reducers 230a, 230b. In this way, the operation of eliminating the difference (bias) in the loads applied to the output shafts 221a, 221b is differential motion.

[0036] Furthermore, for a short period of time until power is distributed evenly to the reducers 230a, 230b arranged on the left and right, the gears in the differential device 210 (for example, the pinion gear 214) rotate, and thereafter only revolve together with the differential case 213 of the reducer 230. At this time, for example, if the pinion gear 214 and the side gear 215 continue to mesh at the same position and power continues to be transmitted only between these gears, there is a risk that the gears will wear out due to minute vibrations. Therefore, the drive transmission device 120 according to this embodiment is provided with a clutch 250, which enables the driving force from the motor 200 to be transmitted directly from each of the output shafts 221a, 221b to the reducer 230.

[0037] (About Clutch 250) Clutch 250 is an example of a power transmission unit. Clutch 250 is provided, for example, between differential device 210 and reducer 230 (reduction devices 230a, 230b), and acts on differential device 210 (for example, contact or separation). Clutch 250 has an OFF state and an ON state. Specifically, the OFF state (separated state: first state) of clutch 250 is a state in which differential motion is performed. More specifically, the OFF state of clutch 250 is a state in which second bevel gear 212 and power transmission unit 222 are separated, and pinion gear 214 rotates together with second bevel gear 212, which in turn rotates side gear 215, thereby rotating output shaft 221.

[0038] On the other hand, when the clutch 250 is in the on state (contact state: second state), no differential motion is performed by the differential device 210. Specifically, the output shaft 221 rotates together with the power transmission unit 222. In the contact state, the second bevel gear 212 and the power transmission unit 222 come into contact with each other, and the power transmission unit 222 rotates in accordance with the rotation of the second bevel gear 212. As a result, the rotational force of the second bevel gear 212 is directly transmitted to the output shaft 221. Therefore, in the contact state, the output shaft 221 rotates due to a direct transmission from the second bevel gear 212 and a transmission accompanying the rotation of the side gear 215.

[0039] The control unit 280 switches the clutch 250 between the ON state and the OFF state based on difference information relating to the difference in rotation between the pair of reducers 230a and 230b. The difference information is information indicating the difference in torque between the pair of reducers 230a and 230b. The difference information may also be information indicating the difference in rotation between the pair of reducers 230a and 230b.

[0040] Here, there is a correlation between the difference in rotation between the pair of reducers 230a, 230b and information relating to the rotation input from the motor 200 to the differential gear 210. The information relating to the rotation input from the motor 200 to the differential gear 210 is information about input torque. The information relating to the rotation input from the motor 200 to the differential gear 210 may also be information about the number of rotations. In the following, the information relating to the rotation input from the motor 200 to the differential gear 210 will be described as information about input torque, but the same applies when the information is information about the number of rotations.

[0041] Specifically, the correlation between the input torque and the difference in rotation between the pair of reducers 230a, 230b is such that, for example, the greater the difference in rotation between the pair of reducers 230a, 230b, the greater the input torque input to the differential device 210. There is also a correlation between the input torque input to the differential device 210 and the current value of the motor 200. Specifically, for example, the greater the input torque input to the differential device 210, the greater the current value of the motor 200.

[0042] Therefore, it can be said that there is a correlation between the difference in rotation between the pair of reducers 230a, 230b and the current value of the motor 200. Therefore, in this embodiment, the difference information is information indicating the current value of the motor 200. The current value of the motor 200 can be acquired from the command value of the motor 200, for example.

[0043] In this embodiment, the control unit 280 keeps the clutch 250 in an OFF state (disengaged state) until the input torque input to the differential device 210 reaches a threshold value, thereby causing differential motion. When the input torque reaches or exceeds the threshold value, the control unit 280 switches the clutch 250 to an ON state (contact state) so that the driving force of the motor 200 is directly transmitted from the output shafts 221a, 221b to the reducer 230. The threshold value is, for example, a value at which it can be estimated that there is no imbalance in the loads applied to the output shafts 221a, 221b when the action unit 104 initially moves. Specifically, the threshold value is expressed as a percentage of the current value (100%) at which the rated torque is obtained, and is, for example, a value that is 10% of the rated torque.

[0044] (Example of hardware configuration of control unit 280) Fig. 4 is an explanatory diagram showing an example of the hardware configuration of the control unit 280. As shown in Fig. 3, the control unit 280 includes an AD (analog-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-analog) converter 305.

[0045] AD converter 301 converts analog signals such as an analog signal from an operation unit and an analog signal such as a current value of motor 200 into digital signals. RAM 302 is a memory that can store thresholds used for controlling the on / off of clutch 250, control values ​​for motor 200, and various other data. ROM 303 stores a drive transmission program for operating CPU 304. CPU 304 sends a control signal for switching clutch 250 in accordance with the drive transmission program stored in ROM 303. DA converter 305 converts the control signal, which is a digital value calculated by CPU 304, into an analog signal.

[0046] (Example of drive transmission process performed by control unit 280 according to the embodiment) 5 is a flowchart showing an example of a drive transmission process performed by the control unit 280 according to the embodiment. As shown in FIG. 5, the control unit 280 determines whether or not to start rotating the motor 200 (step S501). The control unit 280 waits until the motor 200 starts rotating (step S501: NO), and when the motor 200 starts rotating (step S501: YES), the control unit 280 detects the input torque based on the current value of the motor 200 (step S502).

[0047] Then, the control unit 280 determines whether the input torque (current value of the motor 200) is equal to or greater than a threshold value (step S503). If the input torque is not equal to or greater than the threshold value (step S503: NO), the control unit 280 turns the clutch 250 off (disengaged state) (step S504), that is, causes differential motion by the differential device 210, and proceeds to step S506. If the input torque is equal to or greater than the threshold value (step S503: YES), the control unit 280 turns the clutch 250 on (contacted state) (step S505), that is, causes the driving force of the motor 200 to be directly transmitted from each output shaft 221a, 221b to the reducer 230.

[0048] Then, the control unit 280 determines whether or not to end the rotation of the motor 200 (step S506). If the rotation of the motor 200 is not to be ended (step S506: NO), the control unit 280 returns to step S502. If the rotation of the motor 200 is to be ended (step S506: YES), the control unit 280 ends the series of processes.

[0049] As described above, the drive transmission device 120 according to this embodiment switches the clutch 250 between a disengaged state and a contacted state based on difference information between the pair of reducers 230. As a result, after the differential motion of the differential device 210 resolves the difference in loads on the pair of output shafts 221, the driving force input from the motor 200 to the differential device 210 can be transmitted to the output shaft 221 not only in conjunction with the rotation of the side gear 215 but also directly from the second bevel gear 212 to the output shaft 221. This prevents power from being continuously transmitted only between the gears of the differential device 210 (for example, between the pinion gear 241 and the side gear 215), thereby reducing wear on the gears. Therefore, according to this embodiment, it is possible to prevent the product life of the differential device 210 from being shortened.

[0050] In this embodiment, the difference information is information indicating the input torque input from the motor 200 to the differential device 210. This makes it possible to easily obtain the difference information without providing a separate sensor or the like. Even if the difference information is information indicating the rotation speed input from the motor 200 to the differential device 210, the difference information can be obtained easily in the same way.

[0051] Furthermore, in this embodiment, the drive transmission device 120 keeps the clutch 250 in the OFF state (disengaged state) until the value indicated by the difference information reaches a threshold value, and when the threshold value is reached, the drive transmission device 120 turns the clutch 250 to the ON state (contacted state). As a result, when the driving of the motor 200 is started and the operation of the acting unit 104 is initiated, if the difference in loads applied to the pair of output shafts 221 is resolved by differential motion, the drive force can be output directly to the output shaft 221. Therefore, it is possible to prevent power from continuing to be transmitted only between the gears of the differential device 210 after the difference in loads is resolved. This makes it possible to reduce wear on the gears.

[0052] (Modification of the embodiment) Next, modified examples of the embodiment will be described. Note that in the following modified examples, the content explained in the above-mentioned embodiment will be omitted as appropriate. Furthermore, the following modified examples and the above-mentioned embodiment can be combined with each other.

[0053] (Variation 1) First, a first modification of the embodiment will be described. In the above-described embodiment, when the input torque of the differential device 210 becomes equal to or greater than a threshold value, the switching of the clutch 250 is controlled. In addition to this configuration, a first modification will be described, in which the switching of the clutch 250 is also controlled when the input torque becomes equal to or greater than a second threshold value that is greater than the threshold value (hereinafter referred to as the "first threshold value").

[0054] In Modification 1, when the value indicated by the difference information reaches a second threshold value higher than the first threshold value, control unit 280 switches clutch 250 to the OFF state (disengaged state) and then switches clutch 250 back to the ON state (contacted state). The second threshold value is a value at which it is estimated that a certain amount of imbalance in the loads applied to output shafts 221a, 221b occurs due to the torsional rigidity inside speed reducers 230a, 230b.

[0055] The first threshold value is, for example, 10% of the current value at which the rated torque is obtained. The second threshold value is, for example, 40% of the current value at which the rated torque is obtained. The first threshold value and the second threshold value can be set to any value.

[0056] (An example of drive transmission processing performed by the control unit 280 according to the first modification) Fig. 6 is a flowchart showing an example of a drive transmission process performed by control unit 280 according to Modification 1. As shown in Fig. 6, control unit 280 determines whether or not to start rotating motor 200 (step S601). Control unit 280 waits until motor 200 starts rotating (step S601: NO), and when motor 200 starts rotating (step S601: YES), control unit 280 detects the input torque based on the current value of motor 200 (step S602).

[0057] Then, control unit 280 determines whether the input torque (current value of motor 200) is equal to or greater than the first threshold value (step S603). If the input torque is not equal to or greater than the first threshold value (step S603: NO), control unit 280 puts clutch 250 in the OFF state (disengaged state) (step S604), that is, causes differential motion by differential device 210, and proceeds to step S609. As a result, when motor 200 starts to be driven and operation of acting unit 104 starts, the differential motion can eliminate the imbalance in the loads applied to output shafts 221a, 221b.

[0058] If the input torque is equal to or greater than the first threshold (step S603: YES), the control unit 280 turns on the clutch 250 (contact state) (step S605), that is, causes the driving force of the motor 200 to be directly transmitted from the output shafts 221a, 221b to the reducer 230. As a result, after the imbalance in the load on the output shafts 221a, 221b is eliminated, the output shafts 221a, 221b rotate due to the direct transmission from the second bevel gear 212 and the transmission accompanying the rotation of the side gear 215.

[0059] Then, the control unit 280 determines whether the input torque (the current value of the motor 200) is equal to or greater than the second threshold (step S606). If the input torque is not equal to or greater than the second threshold (step S606: NO), the control unit 280 proceeds to step S609. If the input torque is equal to or greater than the second threshold (step S606: YES), the control unit 280 puts the clutch 250 in the OFF state (disengaged state) (step S607), that is, causes differential motion by the differential device 210. As a result, even if an imbalance in the loads applied to the output shafts 221a, 221b occurs due to the torsional rigidity inside the reducers 230a, 230b, the imbalance can be eliminated.

[0060] Next, the control unit 280 again switches the clutch 250 on (contact state) (step S608), that is, transmits the driving force of the motor 200 directly from each of the output shafts 221a, 221b to the reducer 230. Then, the control unit 280 determines whether or not to terminate the rotation of the motor 200 (step S609). If the rotation of the motor 200 is not to be terminated (step S609: NO), the control unit 280 returns to step S602. If the rotation of the motor 200 is to be terminated (step S609: YES), the control unit 280 terminates the series of processes.

[0061] In the drive transmission device 120 according to the first modification, when the value indicated by the difference information reaches the second threshold, the clutch 250 is disengaged to cause the differential device 210 to perform differential motion. This allows the differential motion of the differential device 210 to eliminate any imbalance in load on the two output shafts 221 due to a difference in the internal torsional rigidity of the reducer 230. The drive transmission device 120 then engages the clutch 250 to directly transmit the driving force input from the motor 200 to the differential device 210 to the output shaft 221. This allows each output shaft 221 to be rotated by both direct transmission from the second bevel gear 212 and transmission accompanying the rotation of the side gear 215, thereby preventing power from being continuously transmitted only between the gears of the differential device 210 (for example, between the pinion gear 241 and the side gear 215). This reduces wear on the gears, thereby preventing the product life of the differential device 210 from being shortened.

[0062] (Variation 2) Next, a second modification of the embodiment will be described. In the above-described embodiment, the difference information is information indicating the input torque input to the differential device 210. In the second modification, a configuration will be described in which the difference information is information indicating the output torque output from the differential device 210 to the reducers 230a, 230b (torque input to the reducers 230a, 230b). The output torque is the sum of the two torques output from the differential device 210 to the two reducers 230a, 230b. The output torque is detected by a torque sensor.

[0063] The control unit 280 controls the switching of the clutch 250 based on the output torque and a threshold value. Specifically, the control unit 280 controls the switching of the clutch 250 when the output torque becomes equal to or greater than the threshold value. More specifically, the control unit 280 keeps the clutch 250 in an OFF state (disengaged state) until the output torque becomes equal to or greater than the threshold value, so that differential motion is performed by the differential device 210. On the other hand, when the output torque becomes equal to or greater than the threshold value, the control unit 280 keeps the clutch 250 in an ON 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.

[0064] In the second modification, the ON state or the OFF state of the clutch 250 is switched based on the output torque output from the differential device 210 to the reducers 230a and 230b. Even with this configuration, it is possible to prevent power from being continuously transmitted only between the gears of the differential device 210 (for example, between the pinion gear 241 and the side gear 215), thereby suppressing wear on the gears.

[0065] (Variation 3) Next, a third modification of the embodiment will be described. In the second modification described above, the difference information is the sum of the two torques output from the differential device 210 to the two reducers 230a, 230b. In the third modification, a configuration will be described in which the difference information is a value indicating the difference in rotation related to the outputs of the pair of reducers 230a, 230b.

[0066] Specifically, in Modification 3, the value indicating the difference in rotation regarding the output is, for example, the difference in output values ​​output from the two reducers 230a, 230b. The output value is, for example, the output torque output from the pair of reducers 230a, 230b. However, the output value may also be the number of rotations output from the pair of reducers 230a, 230b.

[0067] Furthermore, the difference information may be, for example, a value indicating a difference in rotation related to the input of the pair of reducers 230a, 230b. The value indicating a difference in rotation related to the input is the difference in the input values ​​input to the two reducers 230a, 230b. The input value is, for example, the input torque input to the pair of reducers 230a, 230b. However, the input value may also be the number of rotations input to the pair of reducers 230a, 230b. The torque is detected by a torque sensor. The number of rotations is detected by a rotation sensor.

[0068] (An example of drive transmission processing performed by the control unit 280 according to the third modification) Fig. 7 is a flowchart showing an example of a drive transmission process performed by control unit 280 according to Modification 3. As shown in Fig. 7, control unit 280 determines whether or not to start rotating motor 200 (step S701). Control unit 280 waits until motor 200 starts rotating (step S701: NO), and when motor 200 starts rotating (step S701: YES), control unit 280 uses the detection results detected by the torque sensor to detect an output difference between the output torques output by the pair of reducers 230a, 230b (step S702).

[0069] Then, the control unit 280 determines whether the output difference is equal to or less than a threshold value (step S703). The output difference being equal to or less than the threshold value means that it is estimated that there is no imbalance in the loads on the output shafts 221a, 221b. If the output difference is equal to or less than the threshold value (step S703: YES), that is, if it can be estimated that there is no imbalance in the loads on the output shafts 221a, 221b, the control unit 280 turns on the clutch 250 (contact state) (step S704), that is, causes the driving force of the motor 200 to be directly transmitted from the output shafts 221a, 221b to the reducer 230, and proceeds to step S706.

[0070] If the output difference is not equal to or less than the threshold value (step S703: NO), that is, if it can be estimated that an imbalance in the loads applied to the output shafts 221a, 221b has occurred, the control unit 280 puts the clutch 250 into the OFF state (disengaged state) (step S705), that is, causes differential motion by the differential device 210. This makes it possible to reduce the output difference between the output torques output by the pair of reducers 230a, 230b (to be equal to or less than the threshold value).

[0071] That is, if an imbalance in the loads applied to the output shafts 221a, 221b occurs, the imbalance can be eliminated each time the imbalance occurs. Then, in the subsequent processing, it becomes possible to transition from step S703: YES to step S704, so that the driving force of the motor 200 can be directly transmitted from the output shafts 221a, 221b to the reducer 230.

[0072] Then, the control unit 280 determines whether or not to end the rotation of the motor 200 (step S706). If the rotation of the motor 200 is not to be ended (step S706: NO), the control unit 280 returns to step S702. If the rotation of the motor 200 is to be ended (step S706: YES), the control unit 280 ends the series of processes.

[0073] According to the third modification, whenever the difference in the output torques output from the pair of reducers 230 exceeds a threshold value, that is, whenever it is estimated that an imbalance in the loads applied to the output shafts 221 has occurred, the imbalance can be eliminated. After the imbalance is eliminated, the driving force input from the motor 200 to the differential device 210 can be transmitted not only to the output shaft 221 in association with the rotation of the side gear 215, but also directly from the second bevel gear 212 to the output shaft 221. This prevents power from being continuously transmitted only between the gears of the differential device 210 (for example, between the pinion gear 241 and the side gear 215). This reduces wear on the gears.

[0074] (Variation 4) Next, a fourth modification of the embodiment will be described. In the above-described embodiment, the difference information is directly obtained from information indicating the input torque input to the differential device 210. In the fourth modification, a configuration will be described in which the difference information is time information obtained from a timer. In the fourth modification, it is assumed that the relationship between time and torque is known in advance. That is, it is assumed that there is a correspondence between the time information obtained from the timer and the information indicating the input torque. More specifically, for each operation performed by the action unit 104, a relationship between time and torque is associated, such that the input torque at time t0 is T0, the input torque at time t1 is T1, and so on. The control unit 280 controls the switching of the clutch 250 based on the time information.

[0075] Specifically, when a first time period has arrived at which it is estimated that the output torque will be equal to or greater than a threshold value, the control unit 280 controls the switching of the clutch 250. More specifically, the control unit 280 keeps the clutch 250 in an OFF state (disengaged state) until the first time period has arrived, so that differential motion is performed by the differential device 210. On the other hand, when the first time period has arrived, the control unit 280 keeps the clutch 250 in an ON state (contact state), so that the driving force of the motor 200 is directly transmitted from each of the output shafts 221a, 221b to the reducer 230.

[0076] Furthermore, if the time (second time) during which the torsional rigidity inside the reducers 230a, 230b causes an imbalance in the loads applied to the output shafts 221a, 221b is known, the control unit 280 switches the clutch 250 to the OFF state (disengaged state) at the second time, i.e., causes differential motion by the differential device 210. As a result, even if the torsional rigidity inside the reducers 230a, 230b causes an imbalance in the loads applied to the output shafts 221a, 221b, the imbalance can be eliminated based on the timer information. Thereafter, the control unit 280 switches the clutch 250 to the ON state (contacted state) again.

[0077] In the fourth modification, the clutch 250 is switched on or off based on time information obtained from a timer. Even with this configuration, it is possible to prevent power from being continuously transmitted only between the gears of the differential device 210 (for example, between the pinion gear 241 and the side gear 215), thereby reducing wear on the gears.

[0078] (Variation 5) Next, a fifth modification of the embodiment will be described. In the third modification described above, the difference information is a value indicating the difference in rotation related to the output from the pair of reducers 230a, 230b. In the fifth modification, a configuration will be described in which the difference information is a value indicating the rotation of one of the pair of reducers 230a, 230b.

[0079] In Modification 5, the value indicating the rotation of one of the pair of reducers 230a, 230b is, for example, the output value of one of the two reducers 230a, 230b. The output value is, for example, the output torque output from one of the reducers 230. However, the output value may also be the rotation speed output from one of the reducers 230.

[0080] The value indicating the rotation of one of the pair of reducers 230a, 230b may be, for example, an input value of one of the two reducers 230a, 230b. The input value is, for example, an input torque input to one of the reducers 230. However, the input value may also be the number of rotations input to one of the reducers 230.

[0081] The control unit 280 keeps the clutch 250 in the OFF state (disengaged state) and causes differential motion by the differential device 210 until the output value of one of the two reducers 230a, 230b reaches a threshold value. On the other hand, once the threshold value is reached, the control unit 280 turns the clutch 250 on (contacted state) and causes the driving force of the motor 200 to be directly transmitted from each of the output shafts 221a, 221b to the reducer 230.

[0082] In the fifth modification, the clutch 250 is switched between the on state and the off state based on a value indicating the rotation of one of the pair of reducers 230a, 230b. Even with this configuration, it is possible to prevent power from being continuously transmitted only between the gears of the differential device 210 (for example, between the pinion gear 241 and the side gear 215), thereby suppressing wear on the gears.

[0083] The program for implementing the drive transmission device 120 described above may be recorded on a computer-readable recording medium and loaded into a computer system for execution. The term "computer system" as used herein includes hardware such as an OS and peripheral devices. The term "computer-readable recording medium" also refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into a computer system. The term "computer-readable recording medium" also includes devices that retain the program for a certain period of time, such as volatile memory (RAM) within a computer system that serves as a server or client when the program is transmitted via a network such as the Internet or a communication line such as a telephone line. The program may also be transmitted from a computer system storing the program in a storage device to another computer system via a transmission medium or by transmission waves within the transmission medium. The term "transmission medium" used to transmit the program refers to a medium capable of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may also be used to implement some of the functions described above. Furthermore, the above-mentioned functions may be realized in combination with a program already recorded in the computer system, that is, a so-called differential file (differential program).

[0084] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention.

[0085] In the embodiments and modifications disclosed in this specification, when multiple functions are provided in a distributed manner, some or all of the multiple functions may be provided in an integrated manner, and conversely, when multiple functions are provided in an integrated manner, some or all of the multiple functions may be provided in a distributed manner. Regardless of whether the functions are integrated or distributed, it is sufficient that the configuration can achieve the object of the invention. [Explanation of symbols]

[0086] 100... Shovel (construction machine), 120... Drive transmission device, 200... Motor (drive source), 210... Differential device, 211... First bevel gear, 212... Second bevel gear, 213... Differential case, 214... Pinion gear, 215... Side gear, 221a... First output shaft, 221b... Second output shaft, 230a... First reducer, 230b... Second reducer, 250... Clutch (power transmission section), 280... Control section

Claims

1. A drive transmission device that controls the transmission of drive force at any of a plurality of connecting parts, including a connecting part that connects a vehicle body and a boom, a connecting part that connects the boom and an arm, and a connecting part that connects the arm and a bucket, a pair of output shafts connected to a pair of reducers arranged opposite to each other; a differential device that outputs the driving force input from a driving source to the pair of output shafts; a power transmission unit that can be in either a first state in which a difference in load between the pair of output shafts is adjusted by acting on the differential device, or a second state in which the pair of output shafts are directly rotated by the driving force; a control unit that switches the state of the power transmission unit based on difference information regarding a difference in rotation between the pair of reducers; A drive transmission device comprising:

2. the difference information is information indicating an input torque input from the drive source to the differential device, The drive transmission device according to claim 1 .

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

4. the control unit keeps the state at the first state until the value indicated by the difference information reaches a first threshold, and switches the state to the second state when the value reaches the first threshold. The drive transmission device according to any one of claims 1 to 3.

5. the control unit switches the state to the first state when the value indicated by the difference information becomes a second threshold value higher than the first threshold value, and then switches the state to the second state. The drive transmission device according to claim 4.

6. The difference information is a value indicating a difference in rotation regarding an input to the pair of reducers, or a value indicating a difference in rotation regarding an output from the pair of reducers. The drive transmission device according to claim 1 .

7. The car body and a plurality of connecting portions including a connecting portion connecting the vehicle body and a boom, a connecting portion connecting the boom and an arm, and a connecting portion connecting the arm and a bucket; a driving source that generates driving forces at the plurality of connecting portions; a drive transmission device that controls transmission of the drive force at any one of the plurality of connecting portions; a pair of reducers arranged opposite to each other; Equipped with The drive transmission device is a pair of output shafts connected to the pair of reducers; a differential device that outputs the driving force input from the driving source to the pair of output shafts; a power transmission unit that can be in either a first state in which a difference in load between the pair of output shafts is adjusted by acting on the differential device, or a second state in which the pair of output shafts are directly rotated by the driving force; a control unit that switches the state of the power transmission unit based on difference information regarding a difference in rotation between the pair of reducers; Construction machinery equipped with:

8. A drive transmission device that controls the transmission of drive force at any one of a plurality of connecting parts, including a connecting part that connects a vehicle body and a boom, a connecting part that connects the boom and an arm, and a connecting part that connects the arm and a bucket, a pair of output shafts connected to a pair of reducers arranged opposite to each other; a differential device that outputs the driving force input from a driving source to the pair of output shafts; a power transmission unit that can be in either a first state in which a difference in load between the pair of output shafts is adjusted by acting on the differential device, or a second state in which the pair of output shafts are directly rotated by the driving force; a control unit that switches the state of the power transmission unit based on difference information regarding a difference in rotation between the pair of reducers; Equipped with the control unit keeps the state at the first state until the value indicated by the difference information reaches a first threshold, and switches the state to the second state when the value reaches the first threshold. Drive transmission device.

9. a pair of output shafts connected to a pair of reducers arranged opposite to each other; a differential device that outputs a driving force input from a driving source to the pair of output shafts; a power transmission unit that can be in either a first state in which a difference in load between the pair of output shafts is adjusted by acting on the differential device, or a second state in which the pair of output shafts are directly rotated by the driving force; Equipped with a computer of a drive transmission device that controls transmission of the drive force at any one of a plurality of connecting parts including a connecting part that connects a vehicle body and a boom, a connecting part that connects the boom and an arm, and a connecting part that connects the arm and a bucket, A drive transmission method that executes a process for switching the state of the power transmission unit based on difference information regarding a difference in rotation between the pair of reducers.

10. a pair of output shafts connected to a pair of reducers arranged opposite to each other; a differential device that outputs a driving force input from a driving source to the pair of output shafts; a power transmission unit that can be in either a first state in which a difference in load between the pair of output shafts is adjusted by acting on the differential device, or a second state in which the pair of output shafts are directly rotated by the driving force; Equipped with a computer of a drive transmission device that controls transmission of the drive force at any one of a plurality of connecting parts, including a connecting part that connects a vehicle body and a boom, a connecting part that connects the boom and an arm, and a connecting part that connects the arm and a bucket; a program for executing a process for switching the state of the power transmission unit based on difference information relating to a difference in rotation between the pair of reducers;

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