Abnormality determination device and abnormality determination method for drive case

Abstract

To provide an abnormality determination device and an abnormality determination method capable of determining whether a drive case is in a normal state or an abnormal state.SOLUTION: An abnormality determination device 100 for a final reduction gear 20 includes a temperature sensor 37a, a pressure sensor 37b and a controller 38. The final reduction gear 20 includes a housing 30. The housing 30 comprises a fixed housing 31 and a rotating housing 32 rotating relative to the fixed housing 31. The temperature sensor 37a detects a temperature of air in the housing 30. The pressure sensor 37b detects pressure of the air in the housing 30. The controller 38 determines whether the final reduction gear 20 is in a normal state or an abnormal state on the basis of a detection temperature obtained by the temperature sensor 37a and detection pressure obtained by the pressure sensor 37b.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to an abnormality determination device and an abnormality determination method for a drive case. [Background technology]

[0002] 2. Description of the Related Art Conventionally, drive cases filled with lubricating oil are widely used in vehicles.

[0003] For example, Patent Document 1 discloses a caterpillar-type work vehicle (such as a hydraulic excavator or bulldozer) equipped with a final drive gear as a drive case. The final drive gear includes a fixed housing, a rotating housing that rotates relative to the fixed housing, and a seal that seals the gap between the fixed housing and the rotating housing.

[0004] Patent Document 2 discloses a vehicle (for example, a four-wheel drive vehicle) equipped with a coupling device as a drive case. The coupling device includes a fixed housing, a rotating housing that rotates relative to the fixed housing, and a seal portion that seals the gap between the fixed housing and the rotating housing. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Utility Model Application Publication No. 1-140050 [Patent Document 2] JP 2000-297828 A Summary of the Invention [Problem to be solved by the invention]

[0006] In conventional drive cases, it is difficult to quickly discover any abnormality in the sealing performance of the seals, the amount of lubricating oil, or the internal pressure.

[0007] An object of the present disclosure is to provide an abnormality determination device and an abnormality determination method capable of determining whether a drive case is in a normal state or an abnormal state. [Means for solving the problem]

[0008] The drive case abnormality determination device according to the present disclosure includes a temperature sensor, a pressure sensor, and a controller. The drive case has a housing composed of a fixed housing and a rotating housing that rotates relative to the fixed housing. Lubricating oil is sealed in the drive case. The temperature sensor detects at least one of the temperature of the air in the housing, the temperature of the lubricating oil, and the temperature of the housing. The pressure sensor detects the pressure of the air in the housing. The controller determines whether the drive case is in a normal state or an abnormal state based on the detected temperature detected by the temperature sensor and the detected pressure detected by the pressure sensor. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide an abnormality determination device and an abnormality determination method capable of determining whether a drive case is in a normal state or an abnormal state. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a side view of the bulldozer according to the embodiment. [Diagram 2] 1 is a schematic diagram showing the configuration of a final drive unit and an abnormality determination device according to an embodiment of the present invention; [Diagram 3] FIG. 4 is a plan view of the lid according to the embodiment. [Figure 4] 4 is an example of a map stored in a storage unit according to the embodiment. [Diagram 5] FIG. 4 is a flow diagram for explaining an abnormality determination method according to the embodiment. [Figure 6] 1 is a map showing an anomaly graph. [Figure 7] 1 is a map showing an anomaly graph. [Figure 8] 1 is a map showing an anomaly graph. [Figure 9] 1 is a map showing an anomaly graph. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (Bulldozer 1 Configuration) 1 is a side view showing the configuration of a bulldozer 1 according to an embodiment. The bulldozer 1 is an example of a vehicle according to the present disclosure. In the following description, the up-down direction is a direction perpendicular to the ground, the vehicle width direction is a direction parallel to the central axis of a final reduction gear 20 described later, and the front-rear direction is a direction perpendicular to the up-down direction and the vehicle width direction.

[0012] The bulldozer 1 comprises a vehicle body 2, a work implement 3, and a traveling device 4.

[0013] The vehicle body 2 has a cab 11 and an engine 12. In the cab 11, a seat for an operator of the work vehicle to sit in, a display device for displaying various information, levers and pedals for various operations, etc. are arranged. The engine 12 is arranged in front of the cab 11.

[0014] The work implement 3 is disposed in front of the engine 12. The work implement 3 has a blade 14 and a hydraulic cylinder 15. The blade 14 is driven by the hydraulic cylinder 15.

[0015] The traveling device 4 has a pair of tracks 17, a track frame 18, an idler 19, a final reduction gear 20, and a sprocket 5. The sprocket 5 is formed by a plurality of sprocket teeth 21. The sprocket 5 is driven by a hydraulic motor 22 (see FIG. 2 ), which will be described later, via the final reduction gear 20. The pair of tracks 17 are disposed on the left and right sides of the vehicle body 2. The track frame 18 is disposed along the front-to-rear direction. The idler 19 is rotatably supported at the front end of the track frame 18. The final reduction gear 20 is attached to the rear end of the track frame 18. The plurality of sprocket teeth 21 forming the sprocket 5 are attached to the outer periphery of the final reduction gear 20. The tracks 17 are wound around the idler 19 and the sprocket 5. The rotation of the hydraulic motor 22 is reduced by the final reduction gear 20 and transmitted to the sprocket 5. The rotation of the tracks 17 together with the sprocket 5 causes the bulldozer 1 to travel.

[0016] (Configuration of abnormality determination device 100) The configuration of the abnormality determination device 100 for the final drive gear 20 will be described. Fig. 2 is a schematic diagram showing the configuration of the final drive gear 20 and the abnormality determination device 100 according to this embodiment. The left side in Fig. 2 corresponds to the outer side in the vehicle width direction, and the right side corresponds to the inner side in the vehicle width direction. The outer side in the vehicle width direction is the side away from the center in the vehicle width direction of the bulldozer 1, and the inner side in the vehicle width direction is the side approaching the center in the vehicle width direction.

[0017] 1. Final reduction gear 20 2, the final reduction gear 20 has a housing 30, a reduction gear section 33, and a seal section 34. The final reduction gear 20 is an example of a "drive case" in which lubricating oil is sealed.

[0018] [Housing 30] The housing 30 accommodates the hydraulic motor 22 and the reduction gear unit 33. The housing 30 has a fixed housing 31 and a rotating housing 32. Lubricating oil for lubricating the reduction gear unit 33 is sealed in an internal space T1 within the housing 30. The liquid level L1 of the lubricating oil is approximately half the height of the rotating housing 32.

[0019] The fixed housing 31 is fixed to the truck frame 18 (see FIG. 1). The fixed housing 31 rotatably supports the rotatable housing 32. The hydraulic motor 22 is disposed radially inside the fixed housing 31. The radial direction is a direction perpendicular to the central axis M1 of the fixed housing 31. The radial inside means the side closer to the central axis M1. The fixed housing 31 rotatably supports the output shaft 22a of the hydraulic motor 22.

[0020] Here, the fixed housing 31 is formed with a communication hole 31a extending from the internal space T1 toward a sensor device 37 described later. One end of the communication hole 31a opens in a region of the internal space T1 exposed from the lubricating oil, i.e., above the liquid level L1 of the lubricating oil in the internal space T1. In this embodiment, one end of the communication hole 31a opens between the bearing parts 36, but the position can be changed as appropriate. The other end of the communication hole 31a opens on the surface of the fixed housing 31 and is sealed by the sensor device 37. In this embodiment, the other end of the communication hole 31a opens above the motor 22, but the position can be changed as appropriate. Air in the internal space T1 is supplied to the sensor device 37 through the communication hole 31a.

[0021] The rotatable housing 32 is disposed so as to cover the fixed housing 31 from the outer side in the vehicle width direction. The central axis of the rotatable housing 32 coincides with the central axis of the fixed housing 31. A reduction gear unit 33 is disposed on the radially inner side of the rotatable housing 32.

[0022] The rotating housing 32 is composed of a cylindrical portion 45, a lid portion 46, a hub 47, and a cover 48.

[0023] The cylindrical portion 45 is a cylindrical member. Both ends of the cylindrical portion 45 in the vehicle width direction are open.

[0024] The lid portion 46 is a disk-shaped member. The lid portion 46 closes the opening of the tube portion 45 on the vehicle width direction outer side. The lid portion 46 is fixed to the tube portion 45 by a bolt. FIG. 3 is a plan view of the lid portion 46 seen from the vehicle width direction outer side. As shown in FIG. 3, the lid portion 46 has a lid main body 46a, an oil fill hole 46b, and an oil fill plug 46c. The oil fill hole 46b penetrates the lid main body 46a in the vehicle width direction. The opening of the oil fill hole 46b on the vehicle width direction inner side is connected to the internal space T1. The opening of the oil fill hole 46b on the vehicle width direction outer side is closed by the oil fill plug 46c. The oil fill plug 46c is detachably attached to the lid main body 46a. The oil fill plug 46c is provided for adding lubricating oil and checking the oil level.

[0025] The hub 47 is an annular member for supporting the sprocket teeth 21. The hub 47 is disposed between the cylindrical portion 45 and the cover 48. The hub 47 is fixed to both the cylindrical portion 45 and the cover 48 by bolts. The hub 47 is rotatably supported by the fixed housing 31 via the bearing portion 36. The bearing portion 36 divides the internal space T1 into a space in which the seal portion 34 is disposed and a space in which the reduction portion 33 is housed, and lubricating oil can move between the two spaces.

[0026] The cover 48 is an annular member. The cover 48 is disposed on the inner side of the hub 47 in the vehicle width direction. The cover 48 is fixed to the hub 47 with bolts. The cover 48 faces the fixed housing 31. A small gap G1 is provided between the cover 48 and the fixed housing 31. The seal portion 34 is disposed on the radial inner side of the cover 48. The seal portion 34 seals the gap G1 between the cover 48 and the fixed housing 31.

[0027] [Deceleration section 33] The speed reducer 33 is disposed radially inside the rotating housing 32. The speed reducer 33 is lubricated with lubricating oil. The speed reducer 33 transmits the rotation of the hydraulic motor 22 to the rotating housing 32 while reducing the rotation speed.

[0028] The reduction gear unit 33 has a first sun gear 61 , a first planetary carrier 62 , a first planetary gear 63 , a second sun gear 64 , a second planetary gear 65 , a second planetary carrier 66 , and a ring gear 67 .

[0029] The first sun gear 61 is attached to a first sun gear shaft 61a provided at an end of the output shaft 22a of the hydraulic motor 22. The first planetary carrier 62 rotatably supports the first planetary gear 63. The first planetary carrier 62 meshes with the second sun gear 64. The first planetary gear 63 meshes with the first sun gear 61 and a ring gear 67. The second sun gear 64 is loosely fitted to the output shaft 22a. The second planetary gear 65 meshes with the second sun gear 64 and the ring gear 67. The second planetary carrier 66 rotatably supports the second planetary gear 65. The second planetary carrier 66 is formed integrally with the fixed housing 31. The ring gear 67 is formed on the inner circumferential surface of the rotating housing 32.

[0030] [Seal part 34] The seal portion 34 is disposed radially inside the cover 48 of the rotating housing 32. The seal portion 34 seals the gap G1 between the fixed housing 31 and the rotating housing 32 (cover 48). The seal portion 34 prevents the lubricating oil from leaking to the outside of the housing 30.

[0031] The seal portion 34 is a so-called floating seal. The seal portion 34 has a stationary seal ring 71, a rotating seal ring 72, a stationary O-ring 73, and a rotating O-ring 74.

[0032] The stationary seal ring 71 and the rotary seal ring 72 are each annular members made of metal. The stationary O-ring 73 and the rotary O-ring 74 are each annular members made of rubber. The stationary O-ring 73 is sandwiched between the stationary seal ring 71 and the stationary housing 31. The rotary O-ring 74 is sandwiched between the rotary seal ring 72 and the rotary housing 32.

[0033] The rotating seal ring 72 and the rotating O-ring 74 rotate together with the rotating housing 32. The stationary seal ring 71 and the stationary O-ring 73 are fixed to the stationary housing 31. The rotating seal ring 72 rotates while sliding against the stationary seal ring 71, so that the rotating housing 32 rotates relative to the stationary housing 31 while maintaining the seal of the gap G1.

[0034] 2. Abnormality determination device 100 The abnormality determination device 100 for the final drive unit 20 includes a sensor device 37 and a controller 38.

[0035] [Sensor device 37] The sensor device 37 is attached to the fixed housing 31 of the housing 30 .

[0036] The sensor device 37 has a temperature sensor 37a and a pressure sensor 37b. The temperature sensor 37a detects the temperature of the air in the internal space T1 that communicates with the internal space T1 via the communication hole 31a. The temperature sensor 37a outputs the detected temperature to the controller 38. The pressure sensor 37b detects the pressure of the air in the internal space T1 that communicates with the internal space T1 via the communication hole 31a. The pressure sensor 37b outputs the detected pressure to the controller 38.

[0037] [Controller 38] The controller 38 includes an acquisition unit 38a, a storage unit 38b, a determination unit 38c, and a notification unit 38d.

[0038] The acquiring unit 38a of the controller 38 is electrically connected to the sensor device 37. The acquiring unit 38a acquires the detected temperature detected by the temperature sensor 37a and the detected pressure detected by the pressure sensor 37b. The acquiring unit 38a outputs the detected temperature and the detected pressure to the determining unit 38c.

[0039] The memory unit 38b stores a map showing the relationship between the temperature and pressure of the air in the internal space T1. Fig. 4 is an example of the map stored in the memory unit 38b. In the map of Fig. 4, the horizontal axis indicates the temperature of the air in the internal space T1, and the vertical axis indicates the pressure of the air in the internal space T1.

[0040] The map in Figure 4 shows a graph (hereinafter referred to as the "normal graph") that shows the relationship between the air temperature and air pressure (hereinafter referred to as the "normal pressure") in the internal space T1 when the final drive unit 20 is in a normal state.

[0041] In the normal graph, the normal pressure increases as the air temperature in the internal space T1 increases. This is because the higher the air temperature in the internal space T1, the higher the temperature of the lubricating oil becomes, causing it to expand and reducing the volume of the internal space T1.

[0042] The normal graph can be obtained by measuring the relationship between the air temperature and the normal pressure in the internal space T1 in advance or by simulating it in advance. Although the normal graph in Fig. 4 is expressed by a linear function, the shape of the normal graph is not particularly limited and can be expressed by a straight line, a curve, or a combination thereof.

[0043] The judgment unit 38c acquires the detected temperature and the detected pressure from the acquisition unit 38a. The judgment unit 38c acquires a map from the memory unit 38b. The judgment unit 38c uses the acquired map to judge whether the final reduction gear 20 is in a normal state or an abnormal state based on the detected temperature and the detected pressure. The abnormality judgment method will be described later. If the judgment unit 38c judges that the final reduction gear 20 is in an abnormal state, it generates notification information for notifying that the final reduction gear 20 is in an abnormal state. In this embodiment, information indicating the cause of the abnormal state of the final reduction gear 20 is included in the notification information. The judgment unit 38c outputs the generated notification information to the notification unit 38d.

[0044] When the notification unit 38d receives the notification information from the determination unit 38c, it notifies the operator of the bulldozer 1 that the final reduction gear 20 is in an abnormal state. The method of notification is not particularly limited, but for example, a warning message can be displayed on a display device in the cab 11. If the notification information includes the cause of the abnormal state of the final reduction gear 20, it is preferable that the notification unit 38d also notifies the cause.

[0045] (Abnormality determination method) The method of determining whether or not an abnormality has occurred in the final drive unit 20 by the abnormality determination device 100 will be described with reference to Fig. 5. Fig. 5 is a flow chart for explaining the abnormality determination method. The abnormality determination method described below is executed by the determination unit 38c of the controller 38.

[0046] In step S1, the controller 38 acquires the detected temperature and the detected pressure from the acquisition unit 38a, and acquires the map from the storage unit 38b.

[0047] In step S2, the controller 38 plots the detected temperature and pressure data on the acquired map.

[0048] In step S3, the controller 38 refers to a normal graph written in the map to obtain a normal pressure corresponding to the detected temperature.

[0049] In step S4, the controller 38 determines whether the differential pressure between the normal pressure and the detected pressure is equal to or greater than a predetermined value. The value of the predetermined value is not particularly limited, and is set to a value greater than 0. The predetermined value may be set according to the detected temperature.

[0050] If it is determined in step S4 that the differential pressure is not equal to or greater than the predetermined value, then in step S5, the controller 38 determines that the final drive unit 20 is in a normal state, after which the process ends.

[0051] If it is determined in step S4 that the differential pressure is equal to or greater than the predetermined value, then in step S6, the controller 38 determines that the final drive unit 20 is in an abnormal state. Then, the process proceeds to step S7.

[0052] In step S7, the controller 38 determines whether the detected pressure is smaller than the normal pressure.

[0053] If it is determined in step S7 that the detected pressure is lower than the normal pressure, the controller 38 determines in step S8 whether the detected pressure is a negative pressure.

[0054] If it is determined in step S8 that the detected pressure is negative pressure, in step S9, the controller 38 generates first notification information indicating that the air pressure in the housing 30 needs to be returned to atmospheric pressure and outputs it to the notification unit 38d.

[0055] Here, FIG. 6 is a map showing, by a broken line, an abnormality graph in the case where the process proceeds to step S9, that is, where the detected pressure is lower than the normal pressure and is negative pressure. The abnormality of the pressure inside the housing 30 becoming negative pressure is observed, for example, when the oil filler plug 46c (see FIG. 3) is temporarily removed or loosened immediately after the operation of the bulldozer 1 (that is, when the temperature of the lubricating oil is high), and the air inside the housing 30 that has expanded due to the temperature rise is released, and then the operation of the bulldozer 1 is stopped and a considerable amount of time has passed (when the temperature of the lubricating oil returns to normal temperature). If this state is left as it is, there is a risk that foreign matter such as soil and sand will flow into the housing 30 together with the outside air through the seal portion 34 (see FIG. 2) since the pressure inside the housing 30 is negative. Therefore, when the first notification information is notified by the notification unit 38d, the operator can prevent the inflow of foreign matter by temporarily loosening or removing the oil filler plug 46c to return the pressure inside the housing 30 to atmospheric pressure.

[0056] If it is determined in step S8 that the detected pressure is not negative pressure, in step S10, the controller 38 generates second alarm information indicating a possibility of a decrease in the sealing ability of the seal portion 34 or a shortage of lubricating oil, and outputs the second alarm information to the alarm portion 38d.

[0057] 7 and 8 are maps showing, with dashed lines, abnormality graphs when the process proceeds to step S10, i.e., when the detected pressure is lower than the normal pressure and is positive. The abnormality graph in FIG. 7 is observed when the sealing performance of the seal portion 34 is deteriorated. The abnormality graph in FIG. 8 is observed when the amount of lubricating oil is insufficient. Therefore, when the second alarm information is notified by the alarm portion 38d, the operator needs to check the condition of the seal portion 34 and the amount of lubricating oil.

[0058] If it is determined in step S7 that the detected pressure is not smaller than the normal pressure, i.e., if the detected pressure is greater than the normal pressure, then in step S11, the controller 38 determines that there is a possibility that the amount of lubricant is excessive. Then, in step S12, the controller 38 generates third notification information indicating that there is a possibility that the amount of lubricant is excessive, and outputs the third notification information to the notification unit 38d.

[0059] Here, Fig. 9 is a map showing, in broken lines, an abnormality graph when the process proceeds to step S12, that is, when the detected pressure is lower than the normal pressure and the detected pressure is positive. The abnormality graph in Fig. 9 is observed when the amount of lubricant is too much. Therefore, when the third notification information is notified by the notification unit 38d, the operator needs to check the amount of lubricant.

[0060] (Features)

[0061] (1) The controller 38 determines whether the final drive unit 20 (an example of a drive case) is in a normal state or an abnormal state based on the detected temperature and pressure. This makes it possible to quickly discover any abnormality that has occurred in the final drive unit 20.

[0062] (2) The controller 38 determines that the drive case is in an abnormal state if the differential pressure between the normal pressure and the detected pressure is equal to or greater than a predetermined value. In this way, by determining the state based on a comparison with the normal pressure, an abnormality that has occurred in the final drive unit 20 can be found simply and accurately.

[0063] (3) When the detected pressure is lower than the normal pressure and is a negative pressure, the controller 38 generates first notification information indicating that the air pressure in the housing 30 needs to be returned to atmospheric pressure. This makes it possible to prevent foreign matter from entering the housing 30.

[0064] (4) When the detected pressure is lower than the normal pressure and is a positive pressure, the controller 38 generates second alarm information indicating a possibility of a decrease in the sealing performance of the seal portion 34 or an insufficient amount of lubricating oil. This makes it possible to prevent the bulldozer 1 from being operated in a state of decreased sealing performance or insufficient amount of oil.

[0065] (5) When the detected pressure is higher than the normal pressure, the controller 38 generates third notification information indicating that there is a possibility of an excess amount of lubricating oil. This makes it possible to prevent the bulldozer 1 from being operated in a state of excess oil.

[0066] (6) The controller 38 stores a map for obtaining normal pressure. In this way, by determining the state using the map, any abnormality occurring in the final drive unit 20 can be found simply and accurately.

[0067] (Modification of the embodiment) Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the gist of the disclosure.

[0068] (A) In the above embodiment, the controller 38 uses the temperature of the air in the internal space T1 detected by the temperature sensor 37a as the detected temperature, but this is not limited to this.

[0069] The controller 38 may use the temperature of the lubricant as the detected temperature, or may use the temperature of the housing 30 itself as the detected temperature.

[0070] Furthermore, the temperature sensor may detect two or more of the temperature of the air inside the housing 30, the temperature of the lubricating oil, and the temperature of the housing 30. In this case, the controller 38 may use, for example, an average value of the two or more detected temperatures as the detected temperature.

[0071] When the temperature of the lubricant is used as the detected temperature, the temperature sensor may detect the temperature of the lubricant in the internal space T1, or may detect the temperature of the lubricant flowing between the internal space T1 and the motor 22.

[0072] When the temperature of the housing 30 is used as the detected temperature, the temperature sensor may detect the temperature of the outer surface of the housing 30 or may detect the temperature inside the members of the housing 30 .

[0073] (B) In the above embodiment, the controller 38 stores a map for obtaining normal pressure, but this is not limited to the above.

[0074] The controller 38 may store a function for acquiring the normal pressure, or may store a correspondence table for acquiring the normal pressure.

[0075] Furthermore, the controller 38 may store two or more of a map, a function, and a correspondence table for acquiring the normal pressure. In this case, the controller 38 may use, as the normal pressure, an average value of pressures acquired from two or more of the map, the function, and the correspondence table.

[0076] (C) In the above embodiment, the controller 38 includes information indicating the cause of the abnormal state of the final drive unit 20 in the notification information, but this is not limited to the above. The notification information only needs to indicate that the final drive unit 20 is in an abnormal state.

[0077] (D) In ​​the above embodiment, when the detected pressure is lower than the normal pressure and is a positive pressure (step S10 in FIG. 5), the controller 38 may determine whether the sealing performance of the seal portion 34 has deteriorated or whether the amount of lubricating oil is insufficient. Specifically, if the abnormal graph has a similar shape to the normal graph as shown in FIG 7, it can be determined that the sealing performance has deteriorated, and if the abnormal graph has a different shape from the normal graph as shown in FIG 8, it can be determined that the amount of oil is insufficient.

[0078] (E) In the above embodiment, the final reduction gear 20 is used as an example of the drive case, but this is not limited to this. The drive case may be any case that has a housing composed of a fixed housing and a rotating housing. Examples of the drive case include a reduction gear, a coupling, a differential gear, etc.

[0079] (F) In the above embodiment, the bulldozer 1 is used as an example of the work vehicle, but the present invention is not limited to this. Examples of the work vehicle include hydraulic excavators.

[0080] (Appendix 1) The drive case abnormality determination device of the present disclosure is an abnormality determination device for a drive case having a housing composed of a fixed housing and a rotating housing that rotates relative to the fixed housing, and in which lubricating oil is sealed, and is equipped with a temperature sensor that detects at least one of the temperature of the air in the housing, the temperature of the lubricating oil, and the temperature of the housing, a pressure sensor that detects the pressure of the air in the housing, and a controller that determines whether the drive case is in a normal state or an abnormal state based on the detected temperature detected by the temperature sensor and the detected pressure detected by the pressure sensor.

[0081] (Appendix 2) The abnormality determination device described in Appendix 1, wherein the controller determines that the drive case is in an abnormal state if the differential pressure between the normal pressure corresponding to the detected temperature and the detected pressure when the drive case is in a normal state is greater than or equal to a predetermined value.

[0082] (Appendix 3) The abnormality determination device described in Appendix 2, wherein the controller generates first alarm information indicating that the air pressure in the housing needs to be returned to atmospheric pressure when the detected pressure is lower than the normal pressure and the detected pressure is negative pressure.

[0083] (Appendix 4) The abnormality determination device described in Appendix 2 or 3, wherein the drive case is equipped with a seal portion that seals the gap between the fixed housing and the rotating housing, and the controller generates second alarm information indicating a possibility of a decrease in the sealing ability of the seal portion or a shortage of oil in the lubricating oil when the detected pressure is lower than the normal pressure and is positive pressure.

[0084] (Appendix 5) An abnormality determination device as described in any of Appendices 2 to 4, wherein the controller generates third alarm information indicating that there is a possibility of an excess amount of lubricating oil when the detected pressure is greater than the normal pressure.

[0085] (Appendix 6) 6. The abnormality determination device according to claim 2, wherein the controller stores at least one of a map, a function, and a correspondence table for acquiring the normal pressure.

[0086] (Appendix 7) A method for determining an abnormality in a drive case filled with lubricating oil includes detecting at least one of the temperature of the air within a housing formed by a fixed housing and a rotatable housing that rotates relative to the fixed housing, the temperature of the lubricating oil, and the temperature of the housing using a temperature sensor, detecting the pressure of the air within the housing using a pressure sensor, and determining whether the drive case is in a normal state or an abnormal state based on the detected temperature detected by the temperature sensor and the detected pressure detected by the pressure sensor. [Explanation of symbols]

[0087] 1. Bulldozer 5 Sprockets 20 Final reduction gear 30 Housing 33 Reduction section 34 Seal part 37 Sensor Device 37a Temperature sensor 37b Pressure sensor 38 Controller

Claims

1. 1. An abnormality determination device for a drive case having a housing composed of a fixed housing and a rotating housing that rotates relative to the fixed housing, and in which lubricating oil is sealed, comprising: a temperature sensor for detecting at least one of a temperature of the air in the housing, a temperature of the lubricating oil, and a temperature of the housing; a pressure sensor for detecting the pressure of the air within the housing; a controller that determines whether the drive case is in a normal state or an abnormal state based on the detected temperature detected by the temperature sensor and the detected pressure detected by the pressure sensor; An abnormality determination device comprising:

2. the controller determines that the drive case is in an abnormal state when a differential pressure between the detected pressure and a normal pressure corresponding to the detected temperature when the drive case is in a normal state is equal to or greater than a predetermined value; The abnormality determination device according to claim 1 .

3. the controller generates first notification information indicating that the pressure of the air in the housing needs to be returned to atmospheric pressure when the detected pressure is lower than the normal pressure and is a negative pressure. The abnormality determination device according to claim 2 .

4. the drive case includes a seal portion that seals a gap between the fixed housing and the rotating housing, When the detected pressure is lower than the normal pressure and is a positive pressure, the controller generates second notification information indicating that there is a possibility of a decrease in sealing performance of the seal portion or a shortage of the amount of the lubricating oil. The abnormality determination device according to claim 2 .

5. The controller generates third notification information indicating a possibility of an excess amount of the lubricating oil when the detected pressure is higher than the normal pressure. The abnormality determination device according to claim 2 .

6. The controller stores at least one of a map, a function, and a correspondence table for acquiring the normal pressure. The abnormality determination device according to claim 2 .

7. A method for determining an abnormality in a drive case filled with lubricating oil, comprising the steps of: Detecting at least one of an air temperature in a housing formed by a fixed housing and a rotating housing that rotates relative to the fixed housing, a temperature of the lubricating oil, and a temperature of the housing by a temperature sensor; Detecting the pressure of the air within the housing with a pressure sensor; determining whether the drive case is in a normal state or an abnormal state based on the detected temperature detected by the temperature sensor and the detected pressure detected by the pressure sensor; The abnormality determination method includes:

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