Construction machinery

Abstract

The HST brake, which prevents collisions, provides construction machinery that can avoid situations where it cannot come to a complete stop. [Solution] The tire roller (construction machine) 100 is equipped with a controller (control device) 10. The controller 10 performs HST brake control, and after activating the HST brake, it detects with a speed sensor that the movement speed of the tire roller 100 has fallen below a specified speed (step S8). When it determines that the state of being below the specified speed has elapsed for a specified time (step S9), it activates the friction brake (step S10) and performs emergency brake control.

Description

Technical Field

[0001] The present invention relates to construction machinery.

Background Art

[0002] In construction machinery, construction machinery equipped with a hydraulic static transmission (hereinafter also referred to as HST) is generally known. This HST constitutes a closed hydraulic circuit combining a hydraulic axial piston pump (hereinafter also simply referred to as "hydraulic pump") and a hydraulic axial piston motor (hereinafter also simply referred to as "hydraulic motor"), and is a device that transmits power via hydraulic pressure. Specifically, the driving of the traveling system of the construction machinery can be performed by hydraulic oil. In the driving of the traveling system, stepless speed change and switching between neutral, forward, and reverse can be achieved by operating a single lever. Here, in the HST, braking can be applied by stopping the supply of hydraulic oil from the hydraulic pump to the hydraulic motor. This braking operation is called an HST brake.

[0003] As a type of the above-described construction machinery, construction machinery having a compaction wheel and used for asphalt paving of roads and the like has been conventionally used. When compacting a paving surface with the compaction wheel of such construction machinery, driving operations such as aligning the compaction wheel with the road shoulder and centering the vehicle widthwise on the road shoulder are required. In this case, since the operator operates the construction machinery while watching the compaction location and the compaction wheel, attention to the traveling direction is likely to be neglected. If the operator of the construction machinery is only focused on the compaction location, the discovery of obstacles around the construction machinery may be delayed, and there is a possibility that the construction machinery may come into contact with the obstacles.

[0004] In order to prevent such contact with obstacles, construction machinery having a contact prevention function for preventing contact with an obstacle when the obstacle (such as an operator) is detected is known (for example, see Patent Document 1).

[0005] A construction machine equipped with a contact prevention function, such as the one described in Patent Document 1, includes, for example, a vehicle speed sensor that detects the vehicle's travel speed, a braking distance calculation unit that calculates the braking distance from the vehicle speed detected by the vehicle speed sensor, a distance sensor that detects the distance to an obstacle, and a control device that determines the presence or absence of an obstacle based on the detection data from the distance sensor and outputs a brake signal if an obstacle is determined to be present. In such a construction machine, when the measured distance to the obstacle detected by the distance sensor falls below the braking distance calculated by the braking distance calculation unit, a brake signal is output, the HST brake is activated, and the machine stops moving, thus performing HST brake control to avoid contact with the obstacle. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-117066 [Overview of the project] [Problems that the invention aims to solve]

[0007] Incidentally, construction machinery used for road paving is heavy in itself because it compacts asphalt. For example, when heavy construction machinery is on a slope, even if the HST brake is activated as a HST brake control to avoid contact with obstacles as described above, it may not be able to come to a complete stop due to a leak of HST hydraulic fluid. In other words, the construction machinery may continue to move at a very low speed even after the HST brake has been activated.

[0008] This invention has been made in view of these circumstances, and its purpose is to provide a construction machine that can avoid situations in which it cannot come to a complete stop by using an HST brake for contact prevention. [Means for solving the problem]

[0009] To achieve the above objective, the present invention provides a construction machine comprising: a vehicle body; a prime mover mounted on the vehicle body; a hydraulic drive pump driven by the prime mover; and a hydraulic drive motor connected to the hydraulic drive pump in a closed circuit, wherein the construction machine comprises: an obstacle detection device for detecting obstacles around the vehicle body; a friction brake device for stopping the vehicle body's movement by frictional braking force; and a control device for restricting the vehicle body's movement when the obstacle detection device detects an obstacle, wherein the control device executes HST brake control to stop the circulation of hydraulic fluid by the hydraulic drive pump when an obstacle is detected by the obstacle detection device, and executes emergency brake control to activate the friction brake device when the vehicle body continues to move while the HST brake control is being executed. [Effects of the Invention]

[0010] The construction machine of the present invention can forcibly stop if, after detecting an obstacle and activating the HST brake, the machine does not come to a complete stop, by activating a separate friction brake system. Therefore, according to the present invention, it is possible to provide a construction machine that can avoid situations where the machine cannot come to a complete stop due to the HST brake used for contact prevention. [Brief explanation of the drawing]

[0011] [Figure 1] This is a side view showing a tire roller as a construction machine according to an embodiment. [Figure 2] This is a perspective view showing the operating unit of a tire roller. [Figure 3] This is a system configuration diagram for a tire roller. [Figure 4] This is a flowchart showing an example of HST brake control. [Figure 5] This is a flowchart showing an example of emergency brake control according to the first embodiment. [Figure 6] This graph shows an example of the relationship between the speed of a tire roller and the weight of the tire roller. [Figure 7]It is a graph showing an example of the relationship between the elapsed time from when the tire roller reaches a speed below the specified speed and the weight of the tire roller. [Figure 8] It is a flowchart showing an example of emergency brake control according to the second embodiment. [Figure 9] It is a flowchart showing an example of emergency brake control according to the third embodiment. [Figure 10] It is a flowchart showing an example of emergency brake control according to the fourth embodiment. [Figure 11] It is a flowchart showing an example of emergency brake control according to the sixth embodiment. [Figure 12] It is a flowchart showing an example of emergency brake control according to the seventh embodiment. [Embodiments for Carrying Out the Invention]

[0012] [First Embodiment] Hereinafter, the first embodiment of the present invention will be described based on the drawings. In the following description, the front-rear direction, left-right direction, and up-down direction are expressed with reference to an operator sitting on the operator's seat of the construction machine.

[0013] FIG. 1 is a side view showing a tire roller 100 as a construction machine according to the first embodiment. The tire roller 100 is a compaction machine (construction machine) that performs a compaction operation in an asphalt paving work by performing a compaction construction. The tire roller 100 includes a vehicle body 1, front wheels 3, rear wheels 4, a drive unit 5, a watering device 7, an operation unit 9, and a controller (control device) 10.

[0014] The vehicle body 1 incorporates various devices such as a drive unit 5 and a controller 10 inside a frame as a structure. The front wheels 3 and the rear wheels 4 are compaction wheels made of rubber with a flat grounding surface, and it is possible to run the vehicle body 1 by driving the rear wheels 4, and it is possible to decelerate the vehicle body 1 by decelerating the rear wheels 4.

[0015] The drive unit 5 includes an engine 11 as a prime mover, a HST 13, and a drive shaft 15. The engine 11 is an internal combustion engine that operates by being supplied with fuel from a fuel tank (not shown). The HST 13 is a closed hydraulic circuit having a variable displacement hydraulic axial piston pump (hydraulic pump) 13a, a variable displacement hydraulic axial piston motor (hydraulic motor) 13b, and a hydraulic path 13c. The hydraulic pump 13a is a so-called swashplate-type hydraulic pump that uses the driving force of the engine 11 to circulate hydraulic oil, and it is possible to adjust the circulation amount and circulation direction of the hydraulic oil by adjusting the inclination angle of a swashplate (not shown). Further, the hydraulic motor 13b is connected to the hydraulic pump 13a in a closed circuit. Thereby, the HST 13 can circulate the hydraulic oil to the hydraulic motor 13b via the hydraulic path 13c and drive the hydraulic motor 13b by operating the hydraulic pump 13a using the driving force of the engine 11.

[0016] Note that the above-described prime mover is not limited to an engine, and for example, an electric motor driven by electric power supplied from a mounted battery may be used.

[0017] The drive shaft 15 is a shaft member having one end connected to the hydraulic motor 13b of the HST 13 in an interlocking manner and the other end connected to an axle 14 that is the rotation shaft of the rear wheels 4 in an interlocking manner. Thereby, the rear wheels 4 can run the vehicle body 1 by the driving force of the hydraulic motor 13b being transmitted via the drive shaft 15 and the axle 14. Further, since the HST 13 interlocks the hydraulic motor 13b with the rear wheels 4 via the drive shaft 15 and the axle 14, it is possible to decelerate the rear wheels 4 by adjusting the circulation amount of the hydraulic oil by the hydraulic pump 13a.

[0018] Here, in the hydraulic pump 13a, by holding the inclination angle of the above-described swashplate at the neutral position, the circulation of the hydraulic oil in the closed circuit can be stopped, and as a result, a so-called HST brake that brakes the hydraulic motor can be applied.

[0019] Furthermore, the hydraulic motor 13b is equipped with a parking brake device (brake device) 61. The parking brake device 61 is a disc-type friction brake device that applies braking force to the hydraulic motor 13b to stop its drive when the supply of hydraulic fluid is released. In other words, the parking brake device 61 is configured to apply braking force to the hydraulic motor 13b even when the tire roller 100 is not in operation. The parking brake device 61 can be switched on and off by an operator operating a parking brake switch 26 (Figure 3) provided on the operation panel 25 (Figure 2), for example. In addition, the axle 14 is equipped with a service brake device (brake device) 62. The service brake device 62 is a disc-type friction brake device that applies friction braking force to the axle 14 by supplying hydraulic fluid when an operator presses down on the brake pedal 38.

[0020] The parking brake device 61 is a relatively powerful brake that can apply braking force suddenly. The service brake device 62 is a brake that can adjust the braking force according to the amount the brake pedal 38 is operated, and can apply braking force gradually.

[0021] The watering device 7 is a device that sprays and sprinkles water stored in a water tank (not shown) formed within the frame of the vehicle body 1 onto the front wheels 3, rear wheels 4, and the road surface. As a result, the watering device 7 can reduce the adhesion between the front wheels 3 and rear wheels 4 and the asphalt pavement material, thereby suppressing the deterioration of the paved road surface.

[0022] Figure 2 shows a perspective view of the control unit 9 as seen from the rear of the vehicle. The control unit 9 includes a forward / reverse lever 21, a steering wheel 23, and an operation panel 25. This control unit 9 is a device that allows the operator to control the vehicle 1's movement, steering, braking, and other various operations of the vehicle 1.

[0023] The forward / reverse lever 21 is a lever that controls the HST 13 to change the rotation direction of the rear wheels 4 by operating the indicated direction, i.e., the set position of the forward / reverse lever 21, thereby switching the direction of travel of the vehicle body 1 to forward, reverse, or neutral (a neutral state that is neither forward nor reverse, and in which case the HST brake is activated). The steering 23 is a steering device that, when operated by the operator, rotates the front wheels 3 around the vertical axis of the vehicle body, thereby adjusting the direction of travel in the left-right direction of the vehicle body.

[0024] The control panel 25 is an operating device having a monitor 31, a speaker 33, and a lamp 34. The monitor 31 is an LCD panel that displays the vehicle's speed, fuel level, and various other settings. The speaker 33 can emit a buzzer sound, etc. The lamp 34 is a warning light that can illuminate visible light visible to the operator.

[0025] Furthermore, as shown in Figure 1, an accelerator pedal 37 is located below the control unit 9, which is at the operator's feet when they are seated. This allows the operator to accelerate, decelerate, or stop the vehicle 1 by adjusting the amount of pressure (operation) applied to the accelerator pedal 37. A brake pedal 38 is also located below the control unit 9. The operator can adjust the braking force of the service brake device 62 by adjusting the amount of pressure (operation) applied to the brake pedal 38.

[0026] The vehicle body 1 is equipped with a warning light 41, an infrared sensor 43 (obstacle detection device), and a rotation sensor 45 (vehicle speed detection device, direction of travel detection device, status detection sensor). The warning light 41 is mounted, for example, on the roof 2 and emits visible light of multiple colors such as red, yellow, green, and blue towards workers positioned around the vehicle body 1. This warning light 41 is detachable and is removed when the vehicle body 1 is traveling on a public road to distinguish it from an emergency vehicle.

[0027] The infrared sensor 43 is an obstacle detection device that emits infrared rays in the direction of travel of the vehicle body 1 and detects the presence or absence of obstacles in the direction of travel and the distance between the vehicle body 1 and the obstacles. The infrared sensor 43 includes a front infrared sensor 43a, which is located at the front of the vehicle body 1 and detects obstacles located in front of the vehicle body 1, and a rear infrared sensor 43b, which is located at the rear and detects obstacles located behind the vehicle body 1. The front infrared sensor 43a and the rear infrared sensor 43b detect the presence or absence of obstacles and the distance between the vehicle body 1 and the obstacles, and output this information to the controller 10.

[0028] The rotation sensor (state detection sensor) 45 is, for example, installed on the rotation axis of the front wheel 3, and is capable of detecting the speed of the vehicle body 1 based on the rotation speed of the front wheel 3. The rotation sensor 45 is also capable of detecting the current direction of travel of the vehicle body 1 by detecting the direction of rotation of the front wheel 3. The rotation sensor 45 detects the driving state of the vehicle body 1, that is, whether the vehicle body 1 is moving forward, backward, or stopped (stationary). Here, "driving" includes cases where the vehicle body 1 moves in one direction due to inertia, or when it moves in one direction due to its own weight on an incline, etc. The rotation sensor 45 can be any well-known rotation sensor capable of detecting rotational speed and direction of rotation, such as a rotary encoder. The rotation sensor 45 outputs the detection result of the driving state of the vehicle body 1 to the controller 10.

[0029] Figure 3 is an explanatory diagram showing an example of the system configuration of the tire roller 100. The controller 10 is a control device for performing overall control, including the operation control of the drive unit 5, and is composed of input / output devices, storage devices (ROM: Read Only Memory, RAM: Random Access Memory, non-volatile RAM, etc.), a central processing unit (CPU: Central Processing Unit), etc.

[0030] The input side of the controller 10 is electrically connected to the forward / reverse lever 21, the rotation sensor 45, the front infrared sensor 43a, and the rear infrared sensor 43b. As a result, the controller 10 receives information about the direction of movement from the forward / reverse lever 21, that is, information about whether the vehicle body 1 is set to forward, reverse, or neutral. The controller 10 also receives information about the speed of the vehicle body 1 and the current direction of movement from the rotation sensor 45. Furthermore, the controller 10 receives information about the presence or absence of obstacles in front of and behind the vehicle body 1, and the distance between the vehicle body 1 and any obstacles, from the front infrared sensor 43a and the rear infrared sensor 43b.

[0031] Furthermore, the controller 10 receives information regarding the amount of operation of the accelerator pedal 37 detected by the accelerator operation amount detection sensor 47, the amount of operation of the brake pedal 38 detected by the brake operation amount detection sensor 48, and the operator's instruction to operate the parking brake switch 26.

[0032] Furthermore, the controller 10 also receives information from various sensors (state detection sensors) 70 that detect the state of the vehicle body 1, as needed.

[0033] Furthermore, the output side of the controller 10 is electrically connected to the drive unit 5 (engine 11 and HST 13), the friction brake system 60 (parking brake system 61 and service brake system 62), the monitor 31, the speaker 33, the lamp 34, and the warning light 41. This allows the controller 10 to control the acceleration, deceleration, and HST brakes of the vehicle body 1 by controlling the hydraulic pump 13a of the engine 11 and HST 13 of the drive unit 5 in accordance with the amount of operation of the accelerator pedal 37 detected by the accelerator operation amount detection sensor. The controller 10 can also control the service brake system 62 in accordance with the amount of operation of the brake pedal 38 detected by the brake operation amount detection sensor, thereby applying the braking force requested by the operator to the vehicle body 1. In certain cases, the controller 10 can also control the service brake system 62 independently of the operation of the brake pedal 38. Specifically, the controller 10 can automatically activate the service brake system 62. Furthermore, the controller 10 can control the parking brake device 61 in response to the operation of the parking brake switch 26, and the operator can activate the parking brake to park the vehicle 1. In certain cases, the controller 10 can also control the parking brake device 61 without the operation of the parking brake switch 26. Specifically, the controller 10 can automatically activate the parking brake device 61.

[0034] Furthermore, the controller 10 controls the monitor 31 to inform the operator of a predetermined notification video. The controller 10 also controls the speaker 33 to sound a buzzer so that the operator can hear it. The controller 10 also controls the lamp 34 to illuminate it in a predetermined lighting pattern, such as flashing, so that it is visible to the operator. In addition, the controller 10 controls the warning light 41 to provide notifications and warnings around the vehicle body 1.

[0035] Next, the HST brake control (contact prevention function) performed by the controller 10 will be explained in detail. Figure 4 is a flowchart showing an example of the HST brake control process performed in the tire roller 100 according to the first embodiment. Specifically, the process shown in Figure 4 is the process of detecting an obstacle in the direction of travel and automatically activating the HST brake.

[0036] First, the controller 10 acquires the detection result of the vehicle body 1's driving state by the rotation sensor 45 (step S1). The driving state of the vehicle body 1 detected by the rotation sensor 45 refers to the states of whether the vehicle body 1 is moving forward, moving backward, or stopped (stationary), as described above. In the first embodiment, the controller 10 determines that the vehicle body 1 is moving if the rotation speed of the front wheels 3 detected by the rotation sensor 45 is greater than a predetermined value (specified value), and determines that the vehicle body 1 is stopped if the rotation speed of the front wheels 3 is less than or equal to the predetermined value (specified value).

[0037] Next, the controller 10 determines whether the vehicle body 1 is in motion based on the driving state of the vehicle body 1 obtained from the signal from the rotation sensor 45 in step S1 (step S2). If the controller 10 determines that the vehicle body 1 is in motion (Yes in step S2), it detects obstacles in the direction of travel based on information from the infrared sensor 43 corresponding to the current direction of travel of the vehicle body 1 detected by the rotation sensor 45 (step S3).

[0038] On the other hand, if the controller 10 determines that the vehicle body 1 is stopped (stationary) (No in step S2), it returns to step S1 and checks the status of the vehicle body 1 again.

[0039] In step S3, the controller 10 determines whether the distance L from the vehicle body 1 to the obstacle is less than or equal to a predetermined distance L1, based on information from the infrared sensor 43 corresponding to the current direction of travel of the vehicle body 1 (step S4). If the controller 10 determines that the distance L from the vehicle body 1 to the obstacle is less than or equal to a predetermined distance L1 (Yes in step S4), it causes the operator to receive an alarm. Specifically, the controller 10 controls at least one of the monitor 31, speaker 33, and lamp 34 to receive an alarm (step S5).

[0040] Furthermore, the controller 10 outputs a command to activate the HST brake, and the HST brake is activated to automatically stop the vehicle 1 (step S6). This state is called HST brake mode.

[0041] On the other hand, if the controller 10 determines that the distance L between the obstacle and the vehicle body 1 is not less than or equal to a predetermined distance L1 (No in step S4), it repeats the process in step S3.

[0042] In this invention, emergency brake control is performed to prevent situations in which the vehicle body 1 does not come to a complete stop and continues to move for some reason, even though the HST brake has been activated to avoid the risk of contact with an obstacle 50. One of the main reasons why the vehicle body 1 moves despite the HST brake being activated is, for example, that the heavy vehicle body 1 is on an inclined surface. When the vehicle body 1 is on an inclined surface, it is pulled downwards by the component of gravity in a direction parallel to the inclined surface of the surface. This can cause hydraulic leakage in the HST. As a result, the HST brake may not be effective enough. Emergency brake control is a control that, when the HST brake is activated while the vehicle body 1 is on an inclined surface as described above, assesses the state of the vehicle body 1 and activates the emergency brake if it is determined that it will not come to a complete stop. Figure 5 is a flowchart showing an example of the emergency brake control process performed in the tire roller 100 according to the first embodiment. In general terms, the process shown in Figure 5 monitors the state of the vehicle body 1 after the HST brake mode is activated, and if the HST brake is not working, it is performed to stop the vehicle body 1 in an emergency using a brake system separate from the HST brake.

[0043] First, in step S7, the controller 10 determines whether the vehicle body 1 is in HST brake mode. Specifically, the controller 10 detects whether a command to activate the HST brake has been output and determines whether the vehicle body 1 is in HST brake mode (step S7). If a command to activate the HST brake has been output, the controller 10 determines that the vehicle is in HST brake mode. If it is determined that the vehicle is in HST brake mode (Yes in step S7), the controller 10 monitors the speed of the vehicle body 1 from the rotation speed of the front wheel 3 detected by the rotation sensor 45 and determines whether the speed of the vehicle body 1 is below a specified value (step S8).

[0044] On the other hand, if the controller 10 determines that the vehicle body 1 is not in HST brake mode (No in step S7), it determines again whether or not it is in HST brake mode.

[0045] If the speed of vehicle 1 is not below the specified value (No in step S8), return to step S8 and continue measuring the speed of vehicle 1. On the other hand, if the speed of vehicle 1 is below the specified value (Yes in step S8), measure the elapsed time since the speed of vehicle 1 fell below the specified value and determine the elapsed time (step S9).

[0046] In the first embodiment, as described above, the controller 10 determines that the vehicle body 1 is moving when the rotational speed of the front wheels 3 detected by the rotation sensor 45 is greater than a predetermined value (specified value), and determines that the vehicle body 1 is stopped when the rotational speed of the front wheels 3 is less than or equal to the predetermined value (specified value). During HST brake mode, the HST brake is activated, the vehicle body 1 is in a deceleration process, and the speed of the vehicle body 1 decreases. In this process, when the speed of the vehicle body 1 falls below the specified value, it is considered that deceleration has been completed to a certain extent and the vehicle has stopped. However, if there is a hydraulic leak in the HST brake, the speed of the vehicle body 1 may exceed 0 km / h and remain below the specified value for a while, even though it is below the specified value. More specifically, the vehicle body 1 may remain at a speed greater than a predetermined first specified speed and below a second specified speed greater than the first specified speed for a while. Here, the first specified speed only needs to be set to a value that allows for the determination of whether or not the vehicle is continuing to travel. Considering the specifications of the rotation sensor 45 that detects the driving state, for example, 0.2 km / h may be adopted. If there is a hydraulic leak in the HST brake, it is difficult to completely stop the vehicle 1, and the vehicle 1 will continue to travel at a speed below the specified value, which may eventually lead to contact with an obstacle. Therefore, it is determined whether or not a predetermined time (specified time) has elapsed after the speed of the vehicle 1 has fallen below the specified value (step S9). In other words, if the speed of the vehicle 1 falls below the specified value while the HST brake is activated, and the speed is greater than 0 km / h (first specified speed), and remains below the specified value (second specified speed) for a specified time, it is determined that the vehicle has decelerated to some extent and reached a very low speed state, but has not come to a complete stop, and is continuing to travel.

[0047] If the specified time has not elapsed since the vehicle body 1's speed fell below the specified value (second specified speed) (No in step S9), the process returns to step S9 and continues measuring the time. On the other hand, if the specified time has elapsed since the vehicle body 1's speed fell below the specified value (second specified speed) (Yes in step S9), the friction brake is activated to forcibly stop the vehicle body 1 (step S10). For example, a parking brake device 61 is used as the friction brake. In other words, the controller 10 controls and activates the parking brake device 61 to forcibly park the vehicle body 1.

[0048] Furthermore, if the aircraft can be brought to a complete stop using the HST brakes, that is, if the prescribed time has elapsed while the aircraft is at a speed of 0 km / h, the friction brakes may also be activated. In other words, it is not the case that the friction brakes are not applied when the aircraft can be brought to a complete stop using the HST brakes; it is possible to apply the friction brakes to bring the aircraft into a parked state even when the aircraft can be brought to a complete stop using the HST brakes.

[0049] (Effects of the first embodiment) The tire roller according to the first embodiment performs HST brake control, which automatically activates the HST brake when an obstacle is detected, and emergency brake control, which activates the emergency brake separately from the HST brake control. Therefore, according to the tire roller according to the first embodiment, even if the HST brake is activated, if a situation occurs where the vehicle body does not come to a complete stop due to a hydraulic leak and moves at a very low speed, the emergency brake can be forcibly activated, thereby preventing contact with an obstacle.

[0050] Furthermore, emergency brakes have relatively strong braking force and may damage the paved road surface. Damaged paved roads require repaving work, reducing work efficiency. In addition, emergency brakes cause relatively large impacts to the operator and the vehicle, posing some discomfort. For this reason, considering work efficiency and comfort, it is more desirable to activate the emergency brakes only after the vehicle has reached a very low speed to reduce the impact caused by emergency brake control. In this regard, the tire roller according to the first embodiment activates the emergency brakes only after the vehicle has reached a second specified speed or below, i.e., a very low speed state, thereby minimizing the impact caused by the activation of the emergency brakes. For this reason, the tire roller according to the first embodiment is superior not only in safety but also in workability and comfort.

[0051] [Second Embodiment] Next, a tire roller according to the second embodiment will be described based on the drawings. In describing the tire roller according to the second embodiment, components similar to those of the tire roller according to the first embodiment already described will be given the same reference numerals and detailed explanations will be omitted.

[0052] In the second embodiment, the tire roller has a water level sensor installed in the water tank to monitor the amount of water in the tank. The water level sensor is one of the various sensors (state detection sensors) 70 shown in Figure 3 and sends information data to the controller 10. A float-type water level sensor is used for this water level sensor. However, the water level sensor is not limited to a float type, and other water level sensors such as ultrasonic water level sensors may be used.

[0053] In the case of the tire roller 100, the overall weight of the vehicle changes depending on whether the amount of water in the water tank is large or small. Even if the tire roller 100 is on the same slope, if the vehicle is heavy when the tank is full of water, the degree of speed reduction will be smaller and the distance traveled will be longer when entering HST brake mode. Conversely, if the amount of water in the water tank is small and the vehicle is light, the degree of speed reduction when entering HST brake mode will be greater and the distance traveled will tend to be shorter. Therefore, it is preferable to adjust the specified speed and specified time when performing emergency brake control so that the vehicle can stop at a position that maintains a certain distance from obstacles, at least. Specifically, thresholds are determined for the specified speed and specified time corresponding to the weight of the tire roller 100 so that the distance traveled by the vehicle body 1 due to hydraulic leak of the HST brake during HST brake mode is kept constant.

[0054] For example, when determining the thresholds mentioned above by focusing on the weight of the vehicle body 1, the relationship between the weight of the vehicle body 1 and the speed of the vehicle body 1 after entering HST brake mode (Figure 6), and the relationship between the weight of the vehicle body 1 and the elapsed time (Figure 7) should be confirmed in advance. From these relationships, it can be seen that the heavier the vehicle body 1, the less the speed of the vehicle body 1 decreases, and the longer the distance the vehicle body 1 travels. Therefore, the heavier the vehicle body 1, the smaller the time threshold and the larger the speed threshold should be set. Conversely, the lighter the vehicle body 1, the larger the time threshold and the smaller the speed threshold should be set. By doing so, the distance traveled by the vehicle body 1 until it stops can be kept constant in the emergency brake control described later.

[0055] Figure 8 is a flowchart showing an example of the emergency brake control process performed in the tire roller 100 according to the second embodiment.

[0056] First, in step S11, the controller 10 determines whether the vehicle body 1 is in HST brake mode. Specifically, if the controller 10 outputs a command to activate the HST brake, it determines that the vehicle is in HST brake mode. If the controller 10 determines that the vehicle is in HST brake mode (Yes in step S11), it determines whether the amount of water detected by the water volume sensor is equal to or greater than a first threshold (step S12). Here, it is preferable to use, for example, half the maximum capacity of the water tank as the first threshold for the amount of water. This allows the controller to determine the total weight of the vehicle including the water.

[0057] If it is determined that the water volume is equal to or greater than the first threshold (1 / 2 of the maximum capacity of the water tank) (Yes in step S12), the speed threshold is set to speed threshold No. 1 and the elapsed time threshold is set to time threshold No. 1 (step S13). Here, speed threshold No. 1 and time threshold No. 1 correspond to the speed threshold and time threshold when the vehicle weight (including the amount of water) is relatively heavy, which are determined from the relationship between the weight of the vehicle body 1 (including the amount of water) and the speed of the vehicle body 1 after entering the HST brake mode, and the relationship between the weight of the vehicle body 1 (including the amount of water) and the elapsed time, which have been determined in advance.

[0058] On the other hand, if it is determined that the water volume is not equal to or greater than the first threshold (1 / 2 of the maximum capacity of the water tank) (No in step S12), it is determined whether the water volume detected by the water volume sensor is equal to or greater than the second threshold, which is smaller than the first threshold (step S14). Here, the second threshold for the water volume is preferably, for example, 1 / 4 or more of the maximum capacity of the water tank.

[0059] If it is determined that the amount of water is equal to or greater than the second threshold (1 / 4 of the maximum capacity of the water tank) (Yes in step S14), the speed threshold is set to speed threshold No. 2 and the elapsed time threshold is set to time threshold No. 2 (step S15). Here, speed threshold No. 2 and time threshold No. 2 correspond to the speed threshold and time threshold when the vehicle weight (including the amount of water) is lighter than the speed threshold No. 1 and time threshold No. 1 described above, which are determined from the relationship between the weight of the vehicle body 1 and the speed of the vehicle body 1 (including the amount of water) after entering the HST brake mode, and the relationship between the weight of the vehicle body 1 (including the amount of water) and the elapsed time.

[0060] On the other hand, if it is determined that the water volume is not equal to or greater than the second threshold (1 / 4 of the maximum capacity of the water tank) (No in step S14), it is determined whether the water volume detected by the water volume sensor is even less, and a speed threshold corresponding to that water volume is determined, as well as a time threshold (step S16). This determination is repeated the necessary number of times (X times) to determine the speed threshold No. X and the time threshold No. X.

[0061] Next, speed thresholds No. 1 to X corresponding to the water volume are set as the specified speed (second specified speed). Then, the speed of the vehicle body 1 is monitored from the rotation speed of the front wheels 3 detected by the rotation sensor 45, and it is determined whether the speed of the vehicle body 1 is below the specified value (step S17). Here, in the second embodiment, a speed threshold corresponding to the vehicle weight, taking into account the amount of water in the water tank, is adopted as the specified speed (second specified speed). In other words, the heavier the vehicle weight, the less the speed decreases even when the HST brake is applied on an incline, and the easier it is for the vehicle body 1 to move forward. Therefore, regarding the specified speed (second specified speed) that serves as the basis for starting the measurement of elapsed time in the next step, the heavier the vehicle weight, the higher the speed that is adopted as the specified value. Specifically, a table showing the relationship between the weight of the vehicle body 1 and the speed of the vehicle body 1 after entering the HST brake mode, as shown in Figure 6 above, is stored in the controller 10 in advance, and the specified value (second specified speed) is determined based on this table.

[0062] If the speed of vehicle 1 is not below the specified value (second specified speed) (No in step S17), the process returns to step S17 and continues measuring the speed of vehicle 1. On the other hand, if the speed of vehicle 1 falls below the specified value (second specified speed) (Yes in step S17), the elapsed time from the point in time when the speed of vehicle 1 fell below the specified value (second specified speed) is measured, and it is determined whether a predetermined time (specified time) has elapsed (step S18).

[0063] In this second embodiment, time thresholds No. 1 to X corresponding to the vehicle weight, taking into account the amount of water in the water tank, are adopted as specified times. In other words, the heavier the vehicle, the less the speed decreases even when the HST brake is applied on an incline, and the easier it is for the vehicle body 1 to move forward. Therefore, the heavier the vehicle, the shorter the time threshold is set as the specified time. Specifically, a table showing the relationship between the weight of the vehicle body 1 and the elapsed time after entering the HST brake mode, as shown in Figure 7 above, is stored in the controller 10 in advance, and the specified time is determined based on this table.

[0064] If the speed of vehicle 1 falls below the specified value, and is greater than 0 km / h, and remains below the specified value (second specified speed), and the specified time described above has elapsed, it will be determined that the vehicle has decelerated to some extent but has not come to a complete stop.

[0065] If the specified time has not elapsed since the vehicle body 1's speed fell below the specified value (second specified speed) (No in step S18), the process returns to step S18 and continues measuring the time. On the other hand, if the specified time has elapsed since the vehicle body 1's speed fell below the specified value (second specified speed) (Yes in step S18), the controller 10 activates the friction brake to forcibly stop the vehicle body 1 (step S19). For example, a parking brake device 61 is used as the friction brake. In other words, the controller 10 controls and activates the parking brake device 61 to forcibly park the vehicle body 1.

[0066] In the second embodiment, the total weight of the vehicle body 1 was estimated using a water volume sensor, but the invention is not limited to this embodiment. For example, a weight sensor that detects the weight of the loads mounted on the vehicle body 1 may be used. In other words, a weight sensor that detects the weight which changes according to the amount of water stored in the water storage tank can also be used.

[0067] Furthermore, in the above explanation, the total weight of vehicle body 1 was estimated using a water volume sensor, but it is not always necessary to estimate the total weight. For example, the larger the water volume value detected by the water volume sensor, the smaller the time threshold and the larger the speed threshold can be set.

[0068] (Effects of the second embodiment) The tire roller according to the second embodiment has a water level sensor that detects the amount of water in the water tank, and adopts a speed threshold and a time threshold corresponding to the vehicle weight, taking into account the amount of water in the water tank, as the speed threshold (second specified speed) and the specified time, respectively. Specifically, the heavier the tire roller's weight, the higher the speed threshold and the lower the time threshold, thereby suppressing the extension of the distance traveled at a very low speed after entering HST brake mode. In other words, whether the water tank is full and the vehicle weight is heavy, or whether the water tank is nearly empty and the vehicle weight is lighter than when it is full, by adjusting the speed threshold and time threshold, the tire roller can be stopped with a nearly constant distance between the vehicle and the obstacle. From another perspective, the tire roller according to the second embodiment can avoid, as much as possible, the activation of the emergency brake, which has a relatively strong braking force and may not only shock the operator and the vehicle but also damage the paved road surface. If the paved road surface is damaged, the paving work must be redone, but if the activation of the emergency brake is avoided, the need for redoing paving work is eliminated or reduced, improving work efficiency. In other words, the tire roller according to the second embodiment employs conditions that allow the emergency brake to be activated quickly when the vehicle weight is heavy, and conditions that minimize the need for the emergency brake when the vehicle weight is light, thereby achieving both safety and improved work efficiency.

[0069] [Third Embodiment] Next, a tire roller according to the third embodiment will be described based on the drawings. In describing the tire roller according to the third embodiment, components similar to those in the tire rollers according to the first and second embodiments already described will be given the same reference numerals and their detailed explanations will be omitted.

[0070] In the third embodiment, the tire roller has a tilt sensor attached to a part of the frame of the vehicle body 1, which monitors the tilt angle of the vehicle body 1 relative to a horizontal state. The tilt sensor is one of the various sensors (state detection sensors) 70 shown in Figure 3, and sends information data to the controller 10. An acceleration-type tilt sensor is used as this tilt sensor. However, the tilt sensor is not limited to the acceleration type, and other tilt sensors such as pendulum type or float type may be used.

[0071] Here, when the tire roller 100 is on an inclined surface, it is pulled downwards by the component of gravity parallel to the inclined surface. The greater the inclination angle, the greater the downward pulling force. Therefore, when the inclination angle is large, the degree of speed reduction is small even when entering HST brake mode, and the distance traveled by the vehicle body 1 increases. When the inclination angle is small, the degree of speed reduction when entering HST brake mode is greater, and the distance traveled by the vehicle body 1 tends to be shorter. Therefore, it is preferable to adjust the specified speed and specified time when performing emergency brake control so that the vehicle can stop at a position that maintains a certain distance from obstacles, at least. Specifically, thresholds are determined for the specified speed and specified time corresponding to the inclination angle of the tire roller 100 so that the distance traveled by the vehicle body 1 due to hydraulic leakage of the HST brake during HST brake mode is kept constant.

[0072] In the third embodiment, the relationship between the tilt angle of the vehicle body 1 and the speed of the vehicle body 1 after entering HST brake mode, and the relationship between the tilt angle of the vehicle body 1 and the elapsed time are confirmed in advance. From these relationships, it can be seen that as the tilt angle of the vehicle body 1 increases, the speed of the vehicle body 1 does not decrease as easily, and the distance the vehicle body 1 travels increases. Therefore, the larger the tilt angle of the vehicle body 1, the smaller the time threshold and the larger the speed threshold are set. Conversely, the smaller the tilt angle of the vehicle body 1, the larger the time threshold and the smaller the speed threshold are set. By doing so, the distance traveled until the vehicle body 1 stops can be kept constant in the emergency brake control described later.

[0073] Figure 9 is a flowchart showing an example of the emergency brake control process performed in the tire roller 100 according to the third embodiment.

[0074] First, in step S21, the controller 10 determines whether the vehicle body 1 is in HST brake mode. Specifically, if the controller 10 outputs a command to activate the HST brake, it determines that the vehicle is in HST brake mode. If the controller 10 determines that the vehicle is in HST brake mode (Yes in step S21), it determines whether the tilt angle of the vehicle body detected by the tilt sensor is greater than or equal to a first threshold (step S22). Here, it is preferable to use, for example, an angle of 30 degrees relative to the horizontal as the first threshold for the tilt angle of the vehicle body. This allows the controller to determine the degree of incline on which the vehicle body is located.

[0075] If it is determined that the vehicle body tilt angle is greater than or equal to the first threshold (30 degrees) (Yes in step S22), the speed threshold is set to speed threshold No. 1 and the elapsed time threshold is set to time threshold No. 1 (step S23). Here, speed threshold No. 1 and time threshold No. 1 correspond to the speed threshold and time threshold when the tilt angle is relatively large, which are determined from the relationship between the vehicle body 1 tilt angle and the vehicle body 1 speed after entering the HST brake mode, and the relationship between the vehicle body 1 tilt angle and the elapsed time, which have been determined in advance.

[0076] On the other hand, if it is determined that the vehicle body tilt angle is not greater than or equal to the first threshold (30 degrees) (No in step S22), it is determined whether the tilt angle detected by the tilt sensor is greater than or equal to a second threshold which is smaller than the first threshold (step S24). Here, it is preferable to use, for example, an angle of 25 degrees relative to the horizontal as the second threshold for the vehicle body tilt angle.

[0077] If it is determined that the vehicle body tilt angle is greater than or equal to the second threshold (25 degrees) (Yes in step S24), the speed threshold is set to speed threshold No. 2 and the elapsed time threshold is set to time threshold No. 2 (step S25). Here, speed threshold No. 2 and time threshold No. 2 correspond to the speed threshold and time threshold when the tilt angle is smaller than that of speed threshold No. 1 and time threshold No. 1 described above, which are determined from the relationship between the vehicle body 1 tilt angle and the vehicle body 1 speed after entering HST brake mode, and the relationship between the vehicle body 1 tilt angle and the elapsed time.

[0078] On the other hand, if it is determined that the vehicle body tilt angle is not greater than or equal to the second threshold (25 degrees) (No in step S24), it is determined whether the tilt angle detected by the tilt sensor is even smaller, and a speed threshold corresponding to that tilt angle is determined, as well as a time threshold (step S26). This determination is repeated the necessary number of times (X times) to determine the speed threshold No. X and the time threshold No. X.

[0079] Next, speed thresholds No. 1 to X corresponding to the inclination angle are set as the specified speed (second specified speed). Then, the speed of the vehicle body 1 is monitored from the rotation speed of the front wheels 3 detected by the rotation sensor 45, and it is determined whether the speed of the vehicle body 1 is below the specified value (step S27). In this third embodiment, the speed threshold corresponding to the inclination angle of the vehicle body is adopted as the specified speed (second specified speed). In other words, on slopes with a large inclination angle, the speed does not decrease easily even when the HST brake is applied, and the vehicle body 1 tends to move forward easily. Therefore, regarding the specified speed (second specified speed) that serves as the basis for starting the measurement of elapsed time in the next step, the system is adjusted so that a relatively high speed is adopted as the specified value as the inclination angle increases. Specifically, similar to the second embodiment, a table showing the relationship between the inclination angle of the vehicle body 1 and the speed of the vehicle body 1 after entering HST brake mode is stored in the controller 10 in advance, and the specified value (second specified speed) is set based on this table.

[0080] If the speed of vehicle 1 is not below the specified value (second specified speed) (No in step S27), the process returns to step S27 and continues measuring the speed of vehicle 1. On the other hand, if the speed of vehicle 1 falls below the specified value (second specified speed) (Yes in step S27), the elapsed time from the point in time when the speed of vehicle 1 fell below the specified value (second specified speed) is measured, and it is determined whether a predetermined time (specified time) has elapsed (step S28).

[0081] In this third embodiment, time thresholds No. 1 to X corresponding to the vehicle body's tilt angle are adopted as specified times. In other words, on steep slopes, the speed does not decrease easily even when the HST brake is applied, and the vehicle body 1 tends to move forward. Therefore, the system is adjusted so that a relatively short time threshold is adopted as the specified time as the tilt angle increases. Specifically, similar to the second embodiment, a table showing the relationship between the vehicle body 1's tilt angle and the elapsed time since entering HST brake mode is stored in the controller 10 in advance, and the specified time is set based on this table.

[0082] If the speed of vehicle 1 falls below the specified value, and is greater than 0 km / h, and remains below the specified value (second specified speed), and the specified time described above has elapsed, it will be determined that the vehicle has decelerated to some extent but has not come to a complete stop.

[0083] If the specified time has not elapsed since the vehicle body 1's speed fell below the specified value (second specified speed) (No in step S28), the process returns to step S28 and continues measuring the time. On the other hand, if the specified time has elapsed since the vehicle body 1's speed fell below the specified value (second specified speed) (Yes in step S28), the controller 10 activates the friction brake to forcibly stop the vehicle body 1 (step S29). For example, a parking brake device 61 is used as the friction brake. In other words, the controller 10 controls and activates the parking brake device 61 to forcibly park the vehicle body 1.

[0084] (Effects of the third embodiment) The tire roller according to the third embodiment has a tilt sensor that detects the tilt angle of the vehicle body, and consequently the angle of the sloped ground. A speed threshold and a time threshold corresponding to the tilt angle are adopted as a specified speed (second specified speed) and specified time, respectively. Specifically, by adjusting the speed threshold to be set higher and the time threshold to be set lower as the tilt angle of the tire roller increases, it is possible to suppress the increase in the distance over which the vehicle moves at a very low speed after entering HST brake mode. In other words, whether the tilt angle is large or small, by adjusting the speed threshold and time threshold, the tire roller can be stopped with a nearly constant distance between the vehicle body and the obstacle. From another perspective, the tire roller according to the third embodiment can avoid, as much as possible, the activation of the emergency brake, which has a relatively strong braking force and may not only shock the operator and the vehicle body but also damage the paved road surface. If the paved road surface is damaged, the paving work must be redone, but if the activation of the emergency brake is avoided, the need for redoing paving work is eliminated or reduced, improving work efficiency. In other words, the tire roller according to the third embodiment employs conditions that allow the emergency brake to be activated quickly when the inclination angle is large, and conditions that minimize the need for the emergency brake when the inclination angle is small, thereby achieving both safety and improved work efficiency.

[0085] [Fourth Embodiment] Next, a tire roller according to the fourth embodiment will be described based on the drawings. In describing the tire roller according to the fourth embodiment, components similar to those of the tire rollers according to the first to third embodiments already described will be given the same reference numerals and detailed explanations will be omitted.

[0086] In the fourth embodiment, the tire roller has an acceleration sensor attached to a part of the frame of the vehicle body 1 to monitor the acceleration of the vehicle body 1. The acceleration sensor is one of the various sensors (state detection sensors) 70 shown in Figure 3 and sends information data to the controller 10. A capacitive acceleration sensor is used as this acceleration sensor. However, the acceleration sensor is not limited to a capacitive type, and other acceleration sensors such as a piezoresistive type may be used.

[0087] Here, when the tire roller 100 is on an inclined surface, it is pulled downwards by the component of gravity parallel to the inclined surface. The greater the inclination angle, the greater the downward pulling force. Therefore, when the inclination angle is large, even when entering HST brake mode, the degree of speed reduction is small, and the distance traveled by the vehicle body 1 tends to increase. In other words, when the inclination angle is large, the acceleration of the vehicle body 1 toward the inclined surface is large, and the speed does not decrease easily. On the other hand, when the inclination angle is small, the degree of speed reduction when entering HST brake mode is greater, and the distance traveled by the vehicle body 1 tends to be shorter. In other words, when the inclination angle is small, the acceleration of the vehicle body 1 toward the inclined surface is small, and the speed decreases easily. Therefore, regarding the specified speed and specified time when performing emergency brake control, it is preferable to adjust them so that the vehicle can stop at a position that maintains a certain distance from obstacles, at least avoiding contact with them. In more detail, in order to keep the distance the vehicle body 1 moves due to hydraulic leakage of the HST brake during HST brake mode constant, the acceleration of the tire roller 100 is considered, and thresholds are determined for a specified speed and specified time corresponding to the acceleration state toward the downward slope.

[0088] In the fourth embodiment, the relationship between the acceleration of the vehicle body 1 toward the inclined surface after entering HST brake mode (hereinafter also simply referred to as "acceleration") and the speed of the vehicle body 1, as well as the relationship between the acceleration of the vehicle body 1 and the elapsed time, are confirmed in advance. From these relationships, it can be seen that the greater the acceleration of the vehicle body 1, the less the speed of the vehicle body 1 decreases, and the longer the distance the vehicle body 1 travels. Therefore, the greater the acceleration of the vehicle body 1, the smaller the time threshold and the larger the speed threshold are set. Conversely, the smaller the acceleration of the vehicle body 1, the larger the time threshold and the smaller the speed threshold are set. By doing so, in the emergency brake control described later, the distance traveled until the vehicle body 1 stops can be kept constant.

[0089] Figure 10 is a flowchart showing an example of the emergency brake control process performed in the tire roller 100 according to the fourth embodiment.

[0090] First, in step S41, the controller 10 determines whether the vehicle body 1 is in HST brake mode. Specifically, if the controller 10 outputs a command to activate the HST brake, it determines that the vehicle is in HST brake mode. If the controller 10 determines that the vehicle is in HST brake mode (Yes in step S41), it determines whether the acceleration of the vehicle body detected by the acceleration sensor is equal to or greater than a first threshold (step S42). Here, it is preferable to use, for example, an acceleration of 5G as the first threshold for the acceleration of the vehicle body. This allows the controller to determine the degree of incline on which the vehicle body is located.

[0091] If it is determined that the acceleration of the vehicle body is greater than or equal to the first threshold (5G) (Yes in step S42), the speed threshold is set to speed threshold No. 1 and the elapsed time threshold is set to time threshold No. 1 (step S43). Here, speed threshold No. 1 and time threshold No. 1 correspond to the speed threshold and time threshold when the acceleration is relatively large, which is determined from the relationship between the acceleration of the vehicle body 1 toward the inclined surface and the speed of the vehicle body 1 after entering the HST brake mode, and the relationship between the acceleration of the vehicle body 1 toward the inclined surface and the elapsed time.

[0092] On the other hand, if it is determined that the acceleration of the vehicle body is not equal to or greater than the first threshold (5G) (No in step S42), it is determined whether the acceleration detected by the acceleration sensor is equal to or greater than the second threshold, which is less than the first threshold (step S44). Here, it is preferable to use, for example, an acceleration of 4G as the second threshold for the acceleration of the vehicle body.

[0093] If it is determined that the acceleration of the vehicle body is greater than or equal to the second threshold (4G) (Yes in step S44), the speed threshold is set to speed threshold No. 2 and the elapsed time threshold is set to time threshold No. 2 (step S45). Here, speed threshold No. 2 and time threshold No. 2 correspond to the speed threshold and time threshold when the acceleration is smaller than that of speed threshold No. 1 and time threshold No. 1 described above, which are determined from the relationship between the acceleration of the vehicle body 1 toward the inclined surface and the speed of the vehicle body 1 after entering the HST brake mode, and the relationship between the acceleration of the vehicle body 1 toward the inclined surface and the elapsed time.

[0094] On the other hand, if it is determined that the vehicle's acceleration is not above the second threshold (4G) (No in step S44), it is determined whether the acceleration detected by the acceleration sensor is even smaller, and a speed threshold corresponding to that acceleration is determined, as well as a time threshold (step S46). This determination is repeated the necessary number of times (X times) to determine the speed threshold No. X and the time threshold No. X.

[0095] Next, speed thresholds No. 1 to X corresponding to acceleration are set as the specified speed (second specified speed). Then, the speed of the vehicle body 1 is monitored from the rotation speed of the front wheels 3 detected by the rotation sensor 45, and it is determined whether the speed of the vehicle body 1 is below the specified value (step S47). Here, in the fourth embodiment, the speed threshold corresponding to the acceleration of the vehicle body is adopted as the specified speed (second specified speed). In other words, on slopes with a large incline angle, the acceleration toward the bottom of the incline is large, and even if the HST brake is applied, the speed does not decrease easily and the vehicle body 1 tends to move forward. Therefore, regarding the specified speed (second specified speed) that serves as the basis for starting the measurement of elapsed time in the next step, the larger the acceleration, the higher the speed that is adopted as the specified value. Specifically, similar to the second embodiment, a table showing the relationship between the acceleration of the vehicle body 1 and the speed of the vehicle body 1 after entering HST brake mode is stored in the controller 10 in advance, and the specified value (second specified speed) is set based on this table.

[0096] If the speed of vehicle 1 is not below the specified value (second specified speed) (No in step S47), the process returns to step S47 and continues measuring the speed of vehicle 1. On the other hand, if the speed of vehicle 1 falls below the specified value (second specified speed) (Yes in step S47), the elapsed time from the point in time when the speed of vehicle 1 fell below the specified value (second specified speed) is measured, and it is determined whether or not a predetermined time (specified time) has elapsed (step S48).

[0097] In this fourth embodiment, time thresholds No. 1 to X corresponding to the acceleration of the vehicle body are adopted as specified times. In other words, on slopes with a large incline angle, the acceleration is large, so even when the HST brake is applied, the speed does not decrease easily and the vehicle body 1 tends to move forward. Therefore, the system is adjusted so that a relatively short time threshold is adopted as the specified time as the acceleration is large. Specifically, similar to the second embodiment, a table showing the relationship between the acceleration of the vehicle body 1 after entering HST brake mode and the elapsed time is stored in the controller 10 in advance, and the specified time is set based on this table.

[0098] If the speed of vehicle 1 falls below the specified value, and is greater than 0 km / h, and remains below the specified value (second specified speed), and the specified time described above has elapsed, it will be determined that the vehicle has decelerated to some extent but has not come to a complete stop.

[0099] If the specified time has not elapsed since the vehicle body 1's speed fell below the specified value (second specified speed) (No in step S48), the process returns to step S48 and continues measuring the time. On the other hand, if the specified time has elapsed since the vehicle body 1's speed fell below the specified value (second specified speed) (Yes in step S48), the controller 10 activates the friction brake to forcibly stop the vehicle body 1 (step S49). For example, a parking brake device 61 is used as the friction brake. In other words, the controller 10 controls and activates the parking brake device 61 to forcibly park the vehicle body 1.

[0100] In the fourth embodiment, the method is not limited to the use of an acceleration sensor. The speed of the vehicle body 1 is monitored from the rotational speed of the front wheels 3 detected by the rotation sensor 45. The magnitude of the speed reduction of the vehicle body 1 per unit time, i.e., the rate of speed reduction (degree of deceleration) of the vehicle body 1, is calculated, and this calculated rate of speed reduction is used instead of the acceleration obtained by the acceleration sensor described above. Specifically, the smaller the rate of speed reduction of the vehicle body 1 in HST brake mode (the smaller the degree of deceleration), the less likely the speed is to decrease even when the HST brake is applied. In this case, the time threshold is set smaller and the speed threshold is set larger. Conversely, the larger the rate of speed reduction of the vehicle body 1 (the greater the degree of deceleration), the larger the time threshold is set and the speed threshold is set smaller.

[0101] (Effects of the fourth embodiment) The tire roller according to the fourth embodiment has an acceleration sensor that detects the acceleration of the vehicle body as it moves downward on an incline, and adopts a speed threshold and a time threshold corresponding to the acceleration as a specified speed (second specified speed) and specified time, respectively. Specifically, the greater the acceleration as it moves downward on an incline, the larger the speed threshold is set and the smaller the time threshold is set, thereby suppressing an increase in the distance the tire roller body moves at a very low speed after entering HST brake mode. In other words, whether the acceleration is high or low, by adjusting the speed threshold and the time threshold, the tire roller can be stopped with a nearly constant distance between the vehicle body and the obstacle. From another perspective, the tire roller according to the fourth embodiment can avoid as much as possible the activation of the emergency brake, which has a relatively strong braking force and may not only shock the operator and the vehicle body but also damage the paved road surface. If the paved road surface is damaged, the paving work must be redone, but if the activation of the emergency brake is avoided, the redoing work will not be necessary or will be reduced, improving work efficiency. In other words, the tire roller according to the fourth embodiment employs conditions that allow the emergency brake to be activated quickly when the acceleration toward the bottom of the slope is large, and conditions that minimize the need for the emergency brake when the acceleration toward the bottom of the slope is small, thereby achieving both safety and improved work efficiency.

[0102] [Fifth Embodiment] Next, a tire roller according to the fifth embodiment will be described. In describing the tire roller according to the fifth embodiment, components similar to those of the tire roller according to the first embodiment already described will be given the same reference numerals and their detailed explanation will be omitted.

[0103] The fifth embodiment is the same as the first embodiment, except that a service brake device 62 is used as the friction brake in step S10 in Figure 5.

[0104] In the fifth embodiment, if a specified time has elapsed since the speed of the vehicle body 1 fell below a specified value (second specified speed) (Yes in step S9), the service brake device 62 is activated to forcibly stop the vehicle body 1 (step S10). Specifically, the controller 10 controls and activates the service brake device 62 to forcibly put the vehicle body 1 into a parked state.

[0105] (Effects of the fifth embodiment) In the tire roller according to the fifth embodiment, the machine is parked using a service brake device 62. The service brake device 62 can apply braking force gradually compared to the parking brake device 61, which applies a strong braking force suddenly, thus minimizing the occurrence of situations where the compacted road surface becomes rough even when emergency braking is applied.

[0106] [Sixth Embodiment] Next, a tire roller according to the sixth embodiment will be described based on the drawings. In describing the tire roller according to the sixth embodiment, components similar to those of the tire roller according to the first embodiment already described will be given the same reference numerals and their detailed explanation will be omitted.

[0107] The sixth embodiment is the same as the first embodiment, as is clear from Figure 11, except that a step S60 is inserted after step S9, which determines whether a specified time has elapsed since the speed of the vehicle body 1 fell below a specified value (second specified speed), to determine whether the distance to the obstacle has fallen below a first threshold as a specified distance. Here, it is preferable to adopt a distance of 60 cm as the first threshold for the distance to the obstacle.

[0108] If a specified time has elapsed since the vehicle body 1's speed fell below a specified value (second specified speed) (Yes in step S9), the controller 10 detects the distance between the vehicle body 1 and the obstacle based on information from the infrared sensor 43. If it determines that the distance is below the first threshold (60 cm) (Yes in step S60), it activates the friction brake to forcibly stop the vehicle body 1 (step S10). For example, a parking brake device 61 is used as the friction brake. In other words, the controller 10 controls and activates the parking brake device 61 to forcibly park the vehicle body 1.

[0109] On the other hand, the distance between the vehicle body 1 and the obstacle is detected, and if it is determined that the distance is not below the first threshold (60 cm) (No in step S60), the process returns to step S7 to determine whether or not the vehicle body 1 is in HST brake mode.

[0110] (Effects of the sixth embodiment) In the tire roller according to the sixth embodiment, when the distance between the vehicle body 1 and the obstacle falls below a first threshold (60 cm), it becomes difficult to avoid contact with the obstacle. Therefore, emergency brake control is performed to activate the friction brake when the distance between the vehicle body 1 and the obstacle falls below the first threshold (60 cm). This makes it possible to more reliably prevent contact with obstacles. In addition, during paving work, there are cases where a worker (obstacle) notices the approach of the tire roller (construction machine) and moves away, becoming more than 60 cm away from the vehicle body 1. In such cases, according to the tire roller according to the sixth embodiment, if the worker (obstacle) is more than 60 cm away from the vehicle body 1, it is not necessary to apply the emergency brake (friction brake). By reducing the need to apply unnecessary emergency brakes in this way, it is possible to avoid impacts on the operator and the vehicle body, and it is also less likely that the road surface will become rough, reducing the number of times paving work needs to be redone and improving work efficiency. In other words, the tire roller according to the sixth embodiment immediately activates the emergency brake if the worker (obstacle) is within a distance of 60 cm or less from the vehicle body 1, and avoids activating the emergency brake if the worker (obstacle) is within a distance of 60 cm or more from the vehicle body 1, thereby achieving both safety and improved work efficiency.

[0111] [Seventh Embodiment] Next, a tire roller according to the seventh embodiment will be described based on the drawings. In describing the tire roller according to the seventh embodiment, components similar to those of the tire rollers according to the first to fourth embodiments already described will be given the same reference numerals and detailed explanations will be omitted.

[0112] In the tire roller according to the seventh embodiment, a temperature sensor is attached to a part of the hydraulic fluid piping to detect the temperature of the hydraulic fluid, and the temperature of the hydraulic fluid is monitored. The temperature sensor is one of the various sensors (state detection sensors) 70 shown in Figure 3, and sends information data to the controller 10. A resistance thermometer type temperature sensor is used as this temperature sensor. However, the temperature sensor is not limited to a resistance thermometer type, and other temperature sensors such as thermocouple type or infrared type may be used.

[0113] In the case of HSTs used in tire rollers, the likelihood of hydraulic leaks depends on the viscosity of the hydraulic fluid. In other words, the higher the viscosity of the hydraulic fluid, the less likely hydraulic leaks are to occur, and the lower the viscosity, the more likely hydraulic leaks are to occur. Therefore, if the viscosity of the hydraulic fluid is low, the degree of speed reduction when entering HST brake mode will be small, and the distance traveled by vehicle 1 will increase. Conversely, if the viscosity of the hydraulic fluid is high, the degree of speed reduction when entering HST brake mode will be greater, and the distance traveled by vehicle 1 tends to be shorter. Furthermore, the viscosity of the hydraulic fluid depends on the temperature of the hydraulic fluid. Therefore, it is thought that by monitoring the temperature of the hydraulic fluid, the viscosity of the hydraulic fluid can be determined from that temperature, and the likelihood of hydraulic leaks can be estimated.

[0114] Regarding the specified speed and time for emergency braking control, it is preferable to adjust them so that the vehicle can stop at a position that maintains a certain distance from any obstacles, thus avoiding contact. Specifically, thresholds are determined for the specified speed and time corresponding to the temperature state of the hydraulic fluid, which corresponds to the viscosity of the hydraulic fluid, so that the distance the vehicle body 1 moves due to hydraulic fluid leakage of the HST brake during HST brake mode remains constant.

[0115] In the seventh embodiment, the relationship between the hydraulic fluid temperature and the vehicle body 1 speed after entering HST brake mode, and the relationship between the hydraulic fluid temperature and elapsed time are confirmed in advance. From these relationships, it can be seen that the higher the hydraulic fluid temperature, the less the vehicle body 1 speed decreases, and the longer the distance the vehicle body 1 travels. Therefore, the higher the hydraulic fluid temperature, the smaller the time threshold and the larger the speed threshold are set. Conversely, the lower the hydraulic fluid temperature, the larger the time threshold and the smaller the speed threshold are set. By doing so, the distance traveled until the vehicle body 1 stops can be kept constant in the emergency brake control described later.

[0116] Figure 12 is a flowchart showing an example of the emergency brake control process performed in the tire roller 100 according to the seventh embodiment.

[0117] First, in step S71, the controller 10 determines whether the vehicle body 1 is in HST brake mode. Specifically, if the controller 10 outputs a command to activate the HST brake, it determines that the vehicle is in HST brake mode. If the controller 10 determines that the vehicle is in HST brake mode (Yes in step S71), it determines whether the temperature of the hydraulic fluid detected by the temperature sensor is above a first threshold (step S72). Here, it is preferable to use a temperature of 80°C as the first threshold for the hydraulic fluid temperature. This allows the viscosity of the hydraulic fluid to be determined.

[0118] If it is determined that the hydraulic fluid temperature is above the first threshold (80°C) (Yes in step S72), the speed threshold is set to speed threshold No. 1 and the elapsed time threshold is set to time threshold No. 1 (step S73). Here, speed threshold No. 1 and time threshold No. 1 correspond to the speed threshold and time threshold when the hydraulic fluid temperature is relatively high, which are determined from the relationship between the hydraulic fluid temperature and the speed of the vehicle body 1 after entering the HST brake mode, and the relationship between the hydraulic fluid temperature and the elapsed time, which have been determined in advance.

[0119] On the other hand, if it is determined that the hydraulic fluid temperature is not above the first threshold (80°C) (No in step S72), it is determined whether the hydraulic fluid temperature detected by the temperature sensor is above a second threshold that is lower than the first threshold (step S74). Here, it is preferable to use a temperature of 60°C as the second threshold for the hydraulic fluid temperature.

[0120] If it is determined that the hydraulic fluid temperature is above the second threshold (60°C) (Yes in step S74), the speed threshold is set to speed threshold No. 2 and the elapsed time threshold is set to time threshold No. 2 (step S75). Here, speed threshold No. 2 and time threshold No. 2 correspond to the speed threshold and time threshold when the hydraulic fluid temperature is lower than that of speed threshold No. 1 and time threshold No. 1 described above, which are determined from the relationship between the hydraulic fluid temperature and the speed of the vehicle body 1 after entering the HST brake mode, and the relationship between the hydraulic fluid temperature and the elapsed time, which have been determined in advance.

[0121] On the other hand, if it is determined that the hydraulic fluid temperature is not above the second threshold (60°C) (No in step S74), it is determined whether the hydraulic fluid temperature detected by the temperature sensor is even lower, and a speed threshold corresponding to that hydraulic fluid temperature is determined, as well as a time threshold (step S76). This determination is repeated the required number of times (X times) to determine the speed threshold No. X and the time threshold No. X.

[0122] Next, speed thresholds No. 1 to X corresponding to the hydraulic fluid temperature are set as the specified speed (second specified speed). Then, the speed of the vehicle body 1 is monitored from the rotational speed of the front wheels 3 detected by the rotation sensor 45, and it is determined whether the speed of the vehicle body 1 is below the specified value (step S77). In this seventh embodiment, the speed threshold corresponding to the hydraulic fluid temperature is adopted as the specified speed (second specified speed). In other words, when the hydraulic fluid temperature is high, the viscosity of the hydraulic fluid is low and hydraulic fluid leakage is likely to occur, so even if the HST brake is applied, the speed does not decrease easily and the vehicle body 1 tends to move forward. Therefore, regarding the specified speed (second specified speed) which serves as the basis for starting the measurement of elapsed time in the next step, the higher the hydraulic fluid temperature, the higher the speed that is adopted as the specified value. Specifically, similar to the second embodiment, a table showing the relationship between the hydraulic fluid temperature and the speed of the vehicle body 1 after entering HST brake mode is stored in the controller 10 in advance, and the specified value (specified speed) is set based on this table.

[0123] If the speed of vehicle 1 is not below the specified value (second specified speed) (No in step S77), the process returns to step S77 and continues measuring the speed of vehicle 1. On the other hand, if the speed of vehicle 1 falls below the specified value (second specified speed) (Yes in step S77), the elapsed time from the point in time when the speed of vehicle 1 fell below the specified value (second specified speed) is measured, and it is determined whether a predetermined time (specified time) has elapsed (step S78).

[0124] In this seventh embodiment, time thresholds No. 1 to X corresponding to the hydraulic fluid temperature are adopted as specified times. In other words, when the hydraulic fluid temperature is high, the viscosity of the hydraulic fluid is low and hydraulic fluid leakage is likely to occur, so even when the HST brake is applied, the speed does not decrease easily and the vehicle body 1 tends to move forward. Therefore, the higher the hydraulic fluid temperature, the shorter the time threshold is set as the specified time. Specifically, similar to the second embodiment, a table showing the relationship between the hydraulic fluid temperature and the elapsed time since entering the HST brake mode is stored in the controller 10 in advance, and the specified time is set based on this table.

[0125] If the speed of vehicle 1 falls below the specified value, and is greater than 0 km / h, and remains below the specified value (second specified speed), and the specified time described above has elapsed, it will be determined that the vehicle has decelerated to some extent but has not come to a complete stop.

[0126] If the specified time has not elapsed since the vehicle body 1's speed fell below the specified value (second specified speed) (No in step S78), the process returns to step S78 and continues measuring the time. On the other hand, if the specified time has elapsed since the vehicle body 1's speed fell below the specified value (second specified speed) (Yes in step S78), the controller 10 activates the friction brake to forcibly stop the vehicle body 1 (step S79). For example, a parking brake device 61 is used as the friction brake. In other words, the controller 10 controls and activates the parking brake device 61 to forcibly park the vehicle body 1.

[0127] (Effects of the seventh embodiment) The tire roller according to the seventh embodiment has a temperature sensor that detects the temperature of the hydraulic fluid, and uses a speed threshold and a time threshold corresponding to the hydraulic fluid temperature, and consequently the viscosity of the hydraulic fluid, as the speed threshold (second specified speed) and the specified time threshold, respectively. Specifically, by adjusting the speed threshold to be set higher and the time threshold to be set lower as the hydraulic fluid temperature increases, it is possible to suppress the extension of the distance traveled at a very low speed after entering HST brake mode. In other words, whether the hydraulic fluid temperature is high or low, by adjusting the speed threshold and the time threshold, the tire roller can be stopped with a nearly constant distance between the vehicle and the obstacle. From another perspective, the tire roller according to the seventh embodiment can avoid, as much as possible, the activation of the emergency brake, which has a relatively strong braking force and may not only shock the operator and the vehicle but also damage the paved road surface. If the paved road surface is damaged, the paving work must be redone, but if the activation of the emergency brake is avoided, the need for redoing paving work is eliminated or reduced, improving work efficiency. In other words, the tire roller according to the seventh embodiment employs conditions that allow the emergency brake to activate quickly when the hydraulic fluid temperature is high, and conditions that minimize the need for the emergency brake when the hydraulic fluid temperature is low, thereby achieving both safety and improved work efficiency.

[0128] This concludes the description of the embodiments, but the embodiments of the present invention are not limited to those described above. For example, although the compaction machine 100 was described as an example in the first to seventh embodiments, the configurations of the first to seventh embodiments are not limited to the compaction machine 100, but may be applied to any construction machine equipped with an HST.

[0129] For example, when the present invention is applied to a dump truck, it is preferable to use a weight sensor capable of measuring the weight of the cargo on the truck bed instead of the water volume sensor used in the second embodiment, and to adjust the specified speed and specified time based on the information from the weight sensor.

[0130] Furthermore, in the first to seventh embodiments, friction brakes were used as emergency brakes, but as a braking means, a configuration may be adopted in which the drive unit 5 (engine 11 and HST 13) is controlled to generate a driving force in the opposite direction to the direction in which the obstacle exists, thereby applying braking.

[0131] Furthermore, in the first to seventh embodiments, an infrared sensor 43 is used to detect obstacles, but the obstacle detection device is not limited to an infrared sensor; it may be any other sensor, such as an ultrasonic sensor, as long as it can detect obstacles and measure the distance. [Explanation of Symbols]

[0132] 1. Vehicle body 3. Front wheels 4 Rear wheel (wheel) 5. Drive Unit (HST Drive Device) 10. Controller (control device) 11. Engine (internal combustion engine, prime mover) 13 HST 13a Hydraulic pump (hydraulic pump for travel) 13b Hydraulic motor (hydraulic motor for travel) 13c Hydraulic pathway 21 Forward / Forward Lever 26 Parking brake switch 43. Infrared sensor (obstacle detection device) 45. Rotation Sensor (Vehicle Speed ​​Detection Device, Direction Detection Device, Status Detection Sensor) 61 Parking brake system (friction brake system) 62 Service brake system (friction brake system) 70 Various Sensors (State Detection Sensors) 100 Tire Roller (Construction Machinery)

Claims

1. The car body and, The engine mounted on the aforementioned vehicle body, A hydraulic pump for travel, driven by the aforementioned prime mover, The aforementioned hydraulic pump for travel and the hydraulic motor for travel are connected in a closed circuit, A construction machine equipped with, An obstacle detection device that detects obstacles around the vehicle body, A friction brake device that stops the vehicle's movement by frictional braking force, The vehicle includes a control device that restricts the movement of the vehicle body when an obstacle is detected by the obstacle detection device, The control device executes HST brake control, which stops the circulation of hydraulic fluid by the hydraulic pump for travel, when an obstacle is detected by the obstacle detection device, and executes emergency brake control, which activates the friction brake device, when the vehicle body continues to travel while the HST brake control is being executed. A construction machine characterized by the following features.

2. The vehicle is equipped with a speed sensor that detects the vehicle's speed. The control device executes the emergency brake control when, while the HST brake control is being performed, the vehicle's travel speed, as detected by the speed sensor, is greater than a predetermined first specified speed, and less than or equal to a second specified speed greater than the first specified speed, and a predetermined specified time has elapsed. The construction machine according to feature 1.

3. The construction machine is equipped with a weight sensor that detects the weight of the load mounted on it, The control device sets the second specified speed higher the greater the weight of the mounted object detected by the weight sensor. The construction machine according to feature 2.

4. The aforementioned construction machine includes a water storage tank and The system includes a water volume sensor that detects the amount of water stored in the water storage tank, The control device sets the second specified speed higher the larger the value of the water volume detected by the water volume sensor. The construction machine according to feature 2.

5. The vehicle body is equipped with a tilt sensor that detects the tilt angle, The control device sets the second specified speed higher the greater the tilt angle detected by the tilt sensor. The construction machine according to feature 2.

6. The control device sets the second specified speed higher the smaller the rate of decrease in the vehicle's speed while the HST brake control is being performed. The construction machine according to feature 2.

7. The system includes a temperature sensor for detecting the temperature of the hydraulic fluid, The control device sets the second specified speed higher the higher the temperature of the hydraulic fluid detected by the temperature sensor. The construction machine according to feature 2.

8. The obstacle detection device detects the distance to the obstacle, The control device executes the emergency brake control while the HST brake control is being performed, if the vehicle continues to move and the distance detected by the obstacle detection device falls below a specified distance. The construction machine according to feature 1.

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