Industrial vehicle alarm system

Abstract

To provide a notification device of an industrial vehicle which can properly notify an occupant of the lack of the effectiveness of a drum brake with respect to a brake operation.SOLUTION: A notification device 100 of an industrial vehicle comprises: a break hydraulic pressure sensor 18g for acquiring hydraulic pressure applied to a drum brake; a vehicle speed sensor 5a for acquiring a deceleration degree of the industrial vehicle; an input calculation part 21 for calculating a brake input corresponding to brake torque corresponding to the hydraulic pressure on the basis of the hydraulic pressure and a specification of the drum break; an output calculation part 22 for calculating a brake output corresponding brake torque corresponding to the deceleration degree; and a notification control part 24 for determining whether or not a deviation condition that a deviation of the brake output with respect to the brake input exists is established on the basis of the brake input, the brake output and a prescribed threshold, and notifying an occupant of the occurrence of the lack of the effectiveness of the drum brake with respect to the brake operation when it is determined that the deviation condition is established.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a notification device for industrial vehicles.

Background Art

[0002] Conventionally, there has been known a brake abnormality alarm device that emits a warning sound through an alarm device based on the detection result of a temperature detection device attached to the back side of a brake lining of a drum brake (for example, Patent Document 1).

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] As an example of insufficient braking performance of a drum brake in response to a brake operation, the fade phenomenon of drum brakes can be cited. The fade phenomenon of a drum brake occurs when the lining becomes high temperature and the friction material decomposes, generating gas that forms a film between the lining surface and the inner surface of the drum, resulting in a decrease in the friction coefficient. However, the temperature at which the fade phenomenon occurs may vary depending on the material of the lining. In addition, the fade phenomenon does not necessarily occur immediately when the lining becomes high temperature. Therefore, it is difficult to appropriately notify the occupant with the notification based only on the temperature of the lining as in the above-mentioned prior art.

[0005] An object of the present invention is to provide a notification device for industrial vehicles that can more appropriately notify the occupant of insufficient braking performance of a drum brake in response to a brake operation.

Means for Solving the Problem

[0006] One aspect of the present invention is a notification device for an industrial vehicle equipped with a hydraulic drum brake that brakes the wheels of an industrial vehicle by the brake operation of the occupant of the industrial vehicle, comprising: a hydraulic pressure acquisition unit that acquires the hydraulic pressure applied to the drum brake; a deceleration acquisition unit that acquires the deceleration of the industrial vehicle; an input calculation unit that calculates a brake input corresponding to the braking torque corresponding to the hydraulic pressure based on the hydraulic pressure and the specifications of the drum brake; an output calculation unit that calculates a brake output corresponding to the braking torque corresponding to the deceleration based on the deceleration and the specifications of the industrial vehicle; and a notification control unit that determines whether a discrepancy condition is met in which there is a discrepancy between the brake output and the brake input based on the brake input, brake output and a predetermined threshold, and notifies the occupant that there is insufficient effectiveness of the drum brake in response to the brake operation when it is determined that the discrepancy condition is met.

[0007] In an industrial vehicle notification device according to one aspect of the present invention, brake input and brake output are calculated, and based on the brake input, brake output, and a predetermined threshold, it is determined whether a discrepancy condition is met where the brake output differs from the brake input. Here, the brake input corresponds to the braking torque corresponding to the hydraulic pressure applied to the drum brake. The brake output corresponds to the braking torque corresponding to the deceleration of the industrial vehicle. Therefore, if the discrepancy condition is met, the braking torque corresponding to deceleration differs from the braking torque corresponding to hydraulic pressure, and there is a high possibility that the drum brake is not effective enough in response to the brake operation. Accordingly, by notifying the occupant that the drum brake is not effective enough in response to the brake operation when it is determined that the discrepancy condition is met, it is possible to notify the occupant of the drum brake's effectiveness more appropriately than, for example, notification based only on the lining temperature.

[0008] In one embodiment, the notification device for an industrial vehicle includes an evaluation value calculation unit that calculates an evaluation value obtained by dividing the brake output by the brake input, and the notification control unit may determine that a deviation condition has been met when the evaluation value is less than or equal to a first threshold. In this case, insufficient effectiveness of the drum brake in response to brake operation can be determined by comparing the evaluation value with the first threshold.

[0009] In one embodiment, the notification device for an industrial vehicle includes a temperature acquisition unit that acquires the lining temperature of the drum brake, and the notification control unit may determine that a deviation condition has been met when the lining temperature is above a predetermined temperature threshold and the evaluation value is below a first threshold, and also notify the occupant that a fade phenomenon is occurring in the drum brake. In this case, the insufficient effectiveness of the drum brake in response to braking operations occurring at a lining temperature above a predetermined temperature threshold can be notified to the occupant as a fade phenomenon occurring in the drum brake.

[0010] In one embodiment, the notification device for an industrial vehicle includes an evaluation value calculation unit that calculates the rate of change of an evaluation value obtained by dividing the brake output by the brake input, and a temperature acquisition unit that acquires the lining temperature of the drum brake. The notification control unit may determine that a deviation condition has been met when the lining temperature is above a predetermined temperature threshold and the rate of change of the evaluation value is below a second threshold, and may also notify the occupant that a fade phenomenon is occurring in the drum brake. In this case, it is possible to determine that the drum brake is becoming ineffective in response to the brake operation by comparing the rate of change of the evaluation value with the second threshold. Furthermore, since the drum brake is becoming ineffective in response to the brake operation at a lining temperature above a predetermined temperature threshold, it is possible to notify the occupant that a fade phenomenon is occurring in the drum brake. [Effects of the Invention]

[0011] According to one aspect of the present invention, it is possible to more appropriately inform the occupant of insufficient effectiveness of the drum brake in response to braking operation. [Brief explanation of the drawing]

[0012] [Figure 1] (a) is a side view of a forklift as an example of an industrial vehicle equipped with an industrial vehicle notification device according to one embodiment. (b) is a schematic configuration diagram illustrating the brake system of an industrial vehicle. [Figure 2] This is a schematic block diagram illustrating the configuration of an industrial vehicle notification device according to one embodiment. [Figure 3] This is a schematic diagram illustrating example evaluation values. [Figure 4] This is a flowchart showing an example of controller processing. [Figure 5] This flowchart shows another example of controller processing. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same or equivalent elements will be denoted by the same reference numerals, and redundant descriptions will be omitted.

[0014] Figure 1(a) is a side view of a forklift as an example of an industrial vehicle equipped with an industrial vehicle notification device according to one embodiment. As shown in Figure 1(a), an example of an industrial vehicle equipped with an industrial vehicle notification device according to this embodiment is a counterbalanced electric forklift 1. The forklift 1 comprises a traveling device 2 and a cargo handling device 3 positioned in front of the traveling device 2 for loading and unloading cargo W.

[0015] The running gear 2 includes a vehicle body 4, two front wheels 5 which are drive wheels located on the front of the vehicle body 4, two rear wheels 6 which are steering wheels located on the rear of the vehicle body 4, a running motor 7 which rotates the front wheels 5, a cargo handling motor 8 which rotates a hydraulic pump (not shown) for cargo handling, and a battery 9 which supplies power to the running motor 7 and the cargo handling motor 8.

[0016] The cargo handling device 3 includes a mast 10 erected at the front end of the vehicle body 4, a pair of forks 12 attached to the mast 10 via a lift bracket 11 on which the cargo W is loaded, a lift cylinder 13 for raising and lowering the forks 12, and a tilt cylinder 14 for tilting the mast 10.

[0017] The cargo handling device 3 may be provided with a load sensor 13a. The load sensor 13a is a detector that detects the load of the cargo W loaded on the fork 12 of the forklift 1 (the loaded load of the forklift 1). The load sensor 13a may be, for example, a pressure sensor that detects the pressure of the lift cylinder 13. The load sensor 13a transmits a signal related to the detected pressure of the lift cylinder 13 to the controller 20 described later.

[0018] Fig. 1(b) is a schematic configuration diagram for explaining a brake system for an industrial vehicle. The forklift 1 includes a brake system 15. The brake system 15 is a system for braking the front wheels 5 of the forklift 1 in response to a brake operation performed by an operator (occupant) of the forklift 1. As shown in Fig. 1(b), the brake system 15 includes a brake pedal 16, a master cylinder 17, and a drum brake 18.

[0019] The brake pedal 16 includes a depression portion 16a that is depressed when the operator performs a brake operation. When the depression portion 16a is depressed by the operator, the brake pedal 16 is pressed.

[0020] The master cylinder 17 generates hydraulic pressure for actuating the drum brake 18 when the brake pedal 16 is pressed. The master cylinder 17 includes, for example, a cylinder tube 17a, a piston 17b disposed inside the cylinder tube 17a, a piston rod 17c fixed to the piston 17b, and a spring 17d disposed on a side opposite to the piston rod 17c inside the cylinder tube 17a. When the brake pedal 16 is pressed, the piston rod 17c is pushed by the brake pedal 16, the piston 17b is pushed in against the biasing force of the spring 17d, and hydraulic pressure is generated. The hydraulic pressure generated in the master cylinder 17 is transmitted to the drum brake 18 via hydraulic oil, and the drum brake 18 is actuated. Thereby, the front wheels 5 are braked.

[0021] The drum brake 18 includes a back plate 18a, a brake drum 18b, and a pair of brake shoes 18c. The back plate 18a is a disk-shaped metal member having a through hole formed in the center thereof, and is fixed to the vehicle body 4.

[0022] The brake drum 18b is a bottomed cylindrical cast member, and is disposed so as to open toward the back plate 18a side. The brake drum 18b is attached to the vehicle body 4 so as to be rotatable along with rotation of the front wheel 5. The brake drum 18b is rotatable relative to the back plate 18a.

[0023] The back plate 18a is provided with the pair of brake shoes 18c. Each brake shoe 18c has a semicircular arc shape in a side view, and is disposed such that the outer circumferential surface thereof faces the inner circumferential surface of the brake drum 18b. A brake lining 18d, which is a friction member, is affixed to the outer circumferential surface of the brake shoe 18c. A lining temperature sensor (temperature acquisition unit) 18e may be affixed to the inner circumferential surface of the brake shoe 18c. The lining temperature sensor 18e is a detector that detects the temperature (lining temperature) of the brake lining 18d of the brake drum 18b. The lining temperature sensor 18e transmits a signal related to the detected lining temperature to a controller 20 described later.

[0024] A wheel cylinder 18f is provided between one end portions of the pair of brake shoes 18c. For example, one wheel cylinder 18f is provided in the drum brake 18. When the drum brake 18 is actuated, hydraulic pressure transmitted from a master cylinder 17 is introduced into the interior of the wheel cylinder 18f. A piston (not shown) in the wheel cylinder 18f presses the pair of brake shoes 18c to respectively pivot them outward against the elastic force of a return spring (not shown) for returning the brake shoes 18c to their initial positions. As a result, the brake lining 18d is pressed against the inner circumferential surface of the brake drum 18b.

[0025] In this type of brake system 15, when the operator of the forklift 1 presses down on the brake pedal 16, the hydraulic pressure generated in the master cylinder 17 activates a hydraulic drum brake 18 to decelerate and stop the forklift 1.

[0026] The industrial vehicle notification device 100 is mounted on a forklift 1 and is a device for notifying the operator of the forklift 1 that the drum brake 18 is not working effectively in response to the operator's brake operation (hereinafter also simply referred to as "insufficient effectiveness of the drum brake 18"). Figure 2 is a schematic block diagram illustrating the configuration of an industrial vehicle notification device according to one embodiment. As shown in Figure 2, the industrial vehicle notification device 100 includes, for example, a vehicle speed sensor (deceleration acquisition unit) 5a, a brake hydraulic pressure sensor (hydraulic pressure acquisition unit) 18g, the lining temperature sensor 18e, the load sensor 13a, a notification unit 19, and a controller 20. The vehicle speed sensor 5a, brake hydraulic pressure sensor 18g, lining temperature sensor 18e, load sensor 13a, and notification unit 19 are electrically connected to the controller 20.

[0027] The vehicle speed sensor 5a is a detector that detects the speed of the forklift 1. The vehicle speed sensor 5a is used to calculate acceleration using the detected speed and functions as a deceleration acquisition unit that acquires the deceleration of the forklift 1. As the vehicle speed sensor 5a, for example, a speed sensor that is installed on the travel motor 7 and detects the rotational speed of the travel motor 7 is used. The vehicle speed sensor 5a transmits a signal related to the detected speed to the controller 20.

[0028] The brake hydraulic pressure sensor 18g is an example of a hydraulic pressure acquisition unit that acquires the hydraulic pressure applied to the drum brake 18. The brake hydraulic pressure sensor 18g is installed, for example, on the wheel cylinder 18f and detects the hydraulic pressure of the wheel cylinder 18f that operates the brake shoe 18c. The brake hydraulic pressure sensor 18g transmits a signal related to the detected hydraulic pressure to the controller 20.

[0029] The notification unit 19 is an on-board device for notifying the operator that the drum brake 18 is not working properly. The notification unit 19 may include, for example, a buzzer, a warning light, or a display. The notification unit 19 notifies the operator that the drum brake 18 is not working properly through a buzzer warning sound, a warning light, or the like.

[0030] The controller 20 is an electronic control unit that controls the notification of insufficient effectiveness of the drum brake 18. The controller 20 includes a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), CAN (Controller Area Network) communication circuit, etc. The controller 20 implements various functions, for example, by loading a program stored in ROM into RAM and executing the program loaded into RAM with the CPU. The controller 20 may be composed of multiple electronic control units.

[0031] The controller 20 has, functionally speaking, an input calculation unit 21, an output calculation unit 22, an evaluation value calculation unit 23, and a notification control unit 24.

[0032] The input calculation unit 21 calculates a brake input corresponding to the braking torque that corresponds to the hydraulic pressure applied to the drum brake 18, based on the hydraulic pressure applied to the drum brake 18 and the specifications of the drum brake 18. The hydraulic pressure applied to the drum brake 18 is the hydraulic pressure corresponding to the operator's brake operation. Here, the hydraulic pressure applied to the drum brake 18 is the hydraulic pressure generated in the master cylinder 17 by the operator's operation of pressing the depression portion 16a of the brake pedal 16, which is transmitted to the wheel cylinder 18f of the drum brake 18 and detected by the brake hydraulic pressure sensor 18g. The specifications of the drum brake 18 include the drum radius r of the brake drum 18b and the area A of the wheel cylinder 18f. The area A of the wheel cylinder 18f may be calculated based on the diameter D of the wheel cylinder 18f. The above-mentioned specifications of the drum brake 18 may be stored in advance in the ROM of the controller 20 or the like. The input calculation unit 21 calculates the brake input according to, for example, the following formula (1). Brake input = hydraulic pressure P × area A × drum radius r ... (1)

[0033] The output calculation unit 22 calculates a brake output corresponding to the braking torque that corresponds to the deceleration of the forklift 1, based on the deceleration of the forklift 1 and the specifications of the forklift 1. The deceleration d of the forklift 1 can be, for example, the deceleration value (negative value) of the acceleration calculated based on the vehicle speed detected by the vehicle speed sensor 5a. The specifications of the forklift 1 include the mass (machine mass) M of the forklift 1 and the tire radius R of the front wheels 5. The mass M may include the load of the cargo W. The load of the cargo W may be calculated by converting the pressure of the lift cylinder 13 detected by the load sensor 13a, for example, using a preset relationship between pressure and load. The above specifications of the forklift 1 may be stored in advance in the ROM of the controller 20 or the like. The output calculation unit 22 calculates the brake output, for example, according to the following formula (2). Brake output = mass M × deceleration d × tire radius R ... (2)

[0034] The evaluation value calculation unit 23 may calculate an evaluation value for evaluating whether or not the drum brake 18 is ineffective, based on the brake input and brake output. The rate of change of the evaluation value is the rate of change of the evaluation value over time. For example, the evaluation value calculation unit 23 calculates an evaluation value obtained by dividing the brake output by the brake input. The evaluation value calculation unit 23 may also calculate the rate of change of the evaluation value obtained by dividing the brake output by the brake input. Various methods for calculating the rate of change of the evaluation value can be used. The rate of change of the evaluation value may be the time derivative of the evaluation value, or it may be the value obtained by dividing the difference between the evaluation value at a predetermined time point in the past and the latest evaluation value by the predetermined time.

[0035] Figure 3 is a schematic diagram illustrating the evaluation values. In Figure 3, the horizontal axis represents the lining temperature, the vertical axis represents the evaluation value, and the evaluation value calculated by the evaluation value calculation unit 23 is shown by the solid curve L1. In this embodiment, the evaluation value is considered to be equivalent to the so-called brake efficiency. Brake efficiency refers to the effectiveness coefficient (brake factor) that represents the effectiveness of the drum brake.

[0036] As shown in Figure 3, the evaluation value here tends to decrease as the lining temperature increases. There is a portion of the evaluation value where, when the lining temperature is above a predetermined temperature threshold Thx, it is below a predetermined fade judgment threshold Th1 (first threshold).

[0037] The temperature threshold Thx is a threshold value of the lining temperature used to distinguish whether the insufficient effectiveness of the drum brake 18 is caused only in the high-temperature range, or whether it occurs in both the high-temperature and low-temperature ranges. The temperature threshold Thx can be set by considering the lining temperature when the drum brake 18 is braked to a certain degree. The temperature threshold Thx may be a value that falls within the range of, for example, 150°C to 180°C.

[0038] The fade detection threshold Th1 is a threshold value for evaluation used by the notification control unit 24 (described later) to determine whether or not the drum brake 18 is not working effectively. Examples of insufficient drum brake performance include the fade phenomenon of the drum brake 18. When the drum brake 18 is fading, the lining temperature is relatively high, and the brake output is reduced to a certain extent relative to the brake input. Therefore, the fade detection threshold Th1 can be set to a value greater than the evaluation value when the drum brake 18 is fading when the lining temperature is above the temperature threshold Thx. The fade detection threshold Th1 may also be a value reduced by a predetermined percentage (e.g., 20% to 40%) compared to the evaluation value when the lining temperature is at room temperature. However, "room temperature" here refers to the room temperature of use in brake testing and can be a predetermined temperature of 100°C or less (e.g., around 20°C to 25°C).

[0039] Furthermore, a fade warning threshold Th2 (second threshold) may be used to notify the operator that a fade phenomenon is occurring in the drum brake 18. The fade warning threshold Th2 is a threshold for the rate of change of the evaluation value used by the notification control unit 24 (described later) to determine whether or not a fade phenomenon is occurring in the drum brake 18. The fade warning threshold Th2 can be set, for example, by considering the tangent and slope of the curve of the evaluation value calculated based on data on the rate of change of the friction coefficient for each lining temperature, which has been acquired in advance by testing or the like.

[0040] In the example in Figure 3, when the lining temperature is above the temperature threshold Thx, the rate of change of the evaluation value decreases and the negative slope increases as the lining temperature increases. This trend corresponds to the fact that when the drum brake 18 is about to fade, the lining temperature is at a certain level of high temperature, and the degree to which the brake output decreases in relation to the brake input is expanding. Therefore, the fade warning threshold Th2 can be a predetermined rate of change of the evaluation value (value of the slope of the curve) in the range where the lining temperature is above the temperature threshold Thx. For example, the fade warning threshold Th2 may be the rate of change of the evaluation value at the tangent line at a predetermined point on the curve L1 in the range where the lining temperature is above the temperature threshold Thx and the evaluation value is below the lining temperature at which the evaluation value becomes the fade judgment threshold Th1 (the range of the double arrows in Figure 3) (slope of the dashed line L2).

[0041] The notification control unit 24 controls the notification unit 19 to notify the operator if the drum brake 18 is not working effectively. The notification control unit 24 determines whether a discrepancy condition is met, based on the brake input, brake output, and a predetermined threshold, where there is a discrepancy between the brake output and the brake input.

[0042] The predetermined threshold is a threshold used to determine whether or not the drum brake 18 is not functioning properly, and includes at least the fade determination threshold Th1 described above. In addition to the fade determination threshold Th1 described above, the predetermined threshold may also include at least one of the temperature threshold Thx and the fade warning threshold Th2 described above.

[0043] A discrepancy condition is a condition that includes a condition using brake input, brake output, and a predetermined threshold, and is met when there is a discrepancy between the brake output and the brake input. Here, the discrepancy condition corresponds to whether or not a fade phenomenon is occurring in the drum brake 18, whether or not a fade phenomenon is about to occur in the drum brake 18, or whether or not the drum brake 18 is not working effectively.

[0044] The notification control unit 24 may acquire the lining temperature based on the detection result of the lining temperature sensor 18e. The notification control unit 24 determines, for example, that the first deviation condition is met when the lining temperature is equal to or greater than the temperature threshold Thx and the evaluation value is equal to or less than the fade determination threshold Th1. The first deviation condition corresponds to the condition of whether or not a fade phenomenon is occurring in the drum brake 18. If the notification control unit 24 determines that the first deviation condition is met, it notifies the operator that a fade phenomenon is occurring in the drum brake 18. The notification control unit 24 notifies the operator that a fade phenomenon is occurring in the drum brake 18 by controlling the notification unit 19 in a first manner, for example. The first manner is one that prompts the operator to immediately take action against the fade phenomenon. The first manner may be, for example, a red warning light, a display showing that a fade phenomenon is occurring in the drum brake 18 in red letters or background, etc.

[0045] The notification control unit 24 may determine that the second deviation condition is met if the lining temperature is above the temperature threshold Thx and the rate of change of the evaluation value is below the fade warning threshold Th2. The second deviation condition corresponds to whether or not a fade phenomenon is occurring in the drum brake 18. If the notification control unit 24 determines that the second deviation condition is met, it may notify the operator that a fade phenomenon is occurring in the drum brake 18. The notification control unit 24 may, for example, control the notification unit 19 in the second manner to notify the operator that a fade phenomenon is occurring in the drum brake 18. The second manner is one that encourages the operator to drive in a way that prevents the fade phenomenon from occurring. The second manner is one that provides less perceptual stimulation to the operator compared to the first manner. The second manner may be, for example, a flashing yellow warning light, a display showing that a fade phenomenon is occurring in the drum brake 18 in yellow letters or background, etc.

[0046] The notification control unit 24 determines, for example, that a third deviation condition is met when the lining temperature is less than the temperature threshold Thx and the evaluation value is less than or equal to the fade determination threshold Th1. The third deviation condition corresponds to the condition of whether or not the drum brake 18 is not working effectively. Here, insufficient effectiveness of the drum brake 18 means insufficient effectiveness of the drum brake 18 caused by a reason other than the fade phenomenon. A reason other than the fade phenomenon is, for example, the intrusion of foreign matter (for example, liquids such as water or oil, or parts, etc.) into the brake drum 18b.

[0047] If the notification control unit 24 determines that the third deviation condition has been met, it notifies the operator that the drum brake 18 is not working effectively in response to the operator's brake operation. The notification control unit 24 notifies the operator that the drum brake 18 is not working effectively by controlling the notification unit 19 in the third manner, for example. The third manner is one that informs the operator of the possibility that an abnormality such as foreign matter has occurred inside the brake drum 18b. The third manner is less perceptually stimulating to the operator compared to the second manner. The third manner may be, for example, a yellow warning light, a display prompting inspection of the drum brake 18, etc.

[0048] Figure 4 is a flowchart illustrating an example of controller processing. The processing shown in the flowchart in Figure 4 is repeatedly executed, for example, at predetermined calculation cycles while the forklift 1 is in motion.

[0049] In S11, the controller 20 of the industrial vehicle's notification device 100 calculates the brake input using the input calculation unit 21. The input calculation unit 21 calculates the brake input based on the hydraulic pressure applied to the drum brake 18 and the specifications of the drum brake 18, for example, according to equation (1) above.

[0050] In S12, the controller 20 calculates the brake output using the output calculation unit 22. The output calculation unit 22 calculates the brake output based on the deceleration of the forklift 1 and the specifications of the forklift 1, for example, according to equation (2) above.

[0051] In S13, the controller 20 calculates an evaluation value using the evaluation value calculation unit 23. The evaluation value calculation unit 23 calculates an evaluation value obtained by, for example, dividing the brake output by the brake input.

[0052] In S14, the controller 20 acquires the lining temperature using the notification control unit 24. The notification control unit 24 acquires the lining temperature, for example, based on the detection result of the lining temperature sensor 18e.

[0053] In S15, the controller 20, using the notification control unit 24, determines whether the evaluation value is less than or equal to the fade detection threshold Th1. If the controller 20 determines that the evaluation value is less than or equal to the fade detection threshold Th1, it proceeds to the process in S16. If the controller 20 determines that the evaluation value is not less than or equal to the fade detection threshold Th1 (i.e., the evaluation value is greater than the fade detection threshold Th1), it terminates the process shown in Figure 4.

[0054] In S16, the controller 20, using the notification control unit 24, determines whether the lining temperature is equal to or greater than the temperature threshold Thx. If the controller 20 determines that the lining temperature is equal to or greater than the temperature threshold Thx, it proceeds to the process in S17. If the controller 20 determines that the lining temperature is not equal to or greater than the temperature threshold Thx (i.e., the lining temperature is less than the temperature threshold Thx), it proceeds to the process in S18.

[0055] In S17, the controller 20, via the notification control unit 24, notifies the operator that a fade phenomenon is occurring in the drum brake 18. The notification control unit 24 notifies the operator that a fade phenomenon is occurring in the drum brake 18 by controlling the notification unit 19, for example, in the first mode. After that, the controller 20 terminates the process shown in Figure 4.

[0056] Meanwhile, in S18, the controller 20, via the notification control unit 24, notifies the operator that the drum brake 18 is not working effectively. The notification control unit 24 notifies the operator that the drum brake 18 is not working effectively by controlling the notification unit 19, for example, in the third mode. After that, the controller 20 terminates the process shown in Figure 4.

[0057] Figure 5 is a flowchart showing another example of the controller's processing. The processing shown in the flowchart in Figure 5 is repeatedly executed at predetermined calculation cycles, for example, in parallel with the processing in Figure 4 while the forklift 1 is in motion.

[0058] In S21, the controller 20 calculates the brake input using the input calculation unit 21, in the same manner as in S11 in Figure 4. In S22, the controller 20 calculates the brake output using the output calculation unit 22, in the same manner as in S12 in Figure 4.

[0059] In S23, the controller 20 calculates the rate of change of the evaluation value using the evaluation value calculation unit 23. The evaluation value calculation unit 23 can calculate the rate of change of the evaluation value using various calculation methods, such as the time derivative of the evaluation value.

[0060] In S24, the controller 20 acquires the lining temperature using the notification control unit 24, in the same manner as in S14 in Figure 4.

[0061] In S25, the controller 20, using the notification control unit 24, determines whether the rate of change of the evaluation value is less than or equal to the fade warning threshold Th2. If the controller 20 determines that the rate of change of the evaluation value is less than or equal to the fade warning threshold Th2, it proceeds to the process in S26. If the controller 20 determines that the rate of change of the evaluation value is not less than or equal to the fade warning threshold Th2 (i.e., the rate of change of the evaluation value is greater than the fade warning threshold Th2), it terminates the process shown in Figure 5.

[0062] In S26, the controller 20, using the notification control unit 24, determines whether the lining temperature is equal to or greater than the temperature threshold Thx. If the controller 20 determines that the lining temperature is equal to or greater than the temperature threshold Thx, it proceeds to the process in S27. If the controller 20 determines that the lining temperature is not equal to or greater than the temperature threshold Thx (i.e., the lining temperature is less than the temperature threshold Thx), it terminates the process shown in Figure 5.

[0063] In S27, the controller 20, via the notification control unit 24, notifies the operator that a fade phenomenon is occurring in the drum brake 18. The notification control unit 24 notifies the operator that a fade phenomenon is occurring in the drum brake 18 by controlling the notification unit 19, for example, in the second mode. After that, the controller 20 terminates the process shown in Figure 5.

[0064] According to the notification device 100 for industrial vehicles configured as described above, the brake input and brake output are calculated, and based on the brake input, brake output and predetermined thresholds (the first threshold being a fade judgment threshold Th1 and the second threshold being a fade warning threshold Th2), it is determined whether or not a deviation condition (the first to third deviation conditions) is met, in which there is a discrepancy between the brake output and the brake input. Here, the brake input corresponds to the braking torque corresponding to the hydraulic pressure applied to the drum brake 18. The brake output corresponds to the braking torque corresponding to the deceleration of the forklift 1. Therefore, if a deviation condition is met, the braking torque corresponding to deceleration is deviating from the braking torque corresponding to hydraulic pressure, and there is a high possibility that the drum brake 18 is not effectively braking in response to the brake operation. Therefore, by notifying the operator that the drum brake 18 is not effectively braking in response to the brake operation when it is determined that a deviation condition is met, it is possible to notify the operator of the insufficient effectiveness of the drum brake 18 in response to the brake operation more appropriately than, for example, notification based only on the lining temperature.

[0065] The industrial vehicle notification device 100 includes an evaluation value calculation unit 23 that calculates an evaluation value obtained by dividing the brake output by the brake input. The notification control unit 24 determines that the first or third deviation condition is met when the evaluation value is less than or equal to the fade judgment threshold Th1, which is a first threshold. This makes it possible to determine insufficient effectiveness of the drum brake in response to brake operation by comparing the evaluation value with the fade judgment threshold Th1.

[0066] The industrial vehicle notification device 100 includes a lining temperature sensor 18e that acquires the lining temperature of the drum brake 18. The notification control unit 24 determines that the first deviation condition is met when the lining temperature is equal to or greater than the temperature threshold Thx and the evaluation value is equal to or less than the fade determination threshold Th1. The notification control unit 24 notifies the operator that a fade phenomenon is occurring in the drum brake 18. This allows the operator to be notified that a fading phenomenon is occurring in the drum brake 18 when the drum brake 18 is not effective enough in response to a brake operation that occurs when the lining temperature is equal to or greater than the temperature threshold Thx.

[0067] The industrial vehicle notification device 100 includes an evaluation value calculation unit 23 that calculates the rate of change of an evaluation value obtained by dividing the brake output by the brake input, and a lining temperature sensor 18e that acquires the lining temperature of the drum brake 18. The notification control unit 24 determines that the second deviation condition is met when the lining temperature is above the temperature threshold Thx and the rate of change of the evaluation value is below the second threshold, which is the fade warning threshold Th2. The notification control unit 24 notifies the operator that a fade phenomenon is occurring in the drum brake 18. This makes it possible to determine that the drum brake 18 is becoming ineffective in response to brake operation by comparing the rate of change of the evaluation value with the fade warning threshold Th2. Furthermore, since the drum brake 18 is becoming ineffective in response to brake operation at a lining temperature above the temperature threshold Thx, it is possible to notify the operator that a fade phenomenon is occurring in the drum brake 18.

[0068] Incidentally, the fade phenomenon of the drum brake 18 occurs when the brake lining 18d becomes hot, causing the friction material to decompose and the gas generated forms a film between the surface of the brake lining 18d and the inner surface of the brake drum 18b, reducing the coefficient of friction. However, the temperature at which the fade phenomenon occurs may differ depending on the material of the brake lining 18d. Also, the fade phenomenon does not necessarily occur immediately when the brake lining 18d becomes hot. In this regard, according to the industrial vehicle notification device 100, as a condition for determining whether the drum brake 18 is experiencing a fade phenomenon, the brake input corresponding to the operator's brake pedal force is calculated from the detected value of the hydraulic pressure P of the wheel cylinder 18f, and this brake input is used to determine the deviation condition. This allows for a more accurate capture of the fade phenomenon than a substitute characteristic based solely on lining temperature, enabling a more accurate and appropriate determination. As a result, for example, compared to a determination based solely on lining temperature, it is possible to suppress over-detection of the fade phenomenon and malfunctions in the notification.

[0069] [Differentiation] The present invention is not limited to the embodiments described above. The present invention can be implemented in various forms, including the embodiments described above, with various modifications and improvements based on the knowledge of those skilled in the art.

[0070] In the above embodiment, as an example, the gradient is not considered, assuming that the forklift 1 is traveling on a flat road, but the gradient may be considered. For example, the controller 20 may change the fade determination threshold and the fade warning threshold when the forklift 1 is traveling downhill, based on the detection result of the gradient sensor. The notification control unit 24 may determine whether the deviation condition is met when the forklift 1 is traveling downhill using a fade determination threshold that is greater than the fade determination threshold Th1. The notification control unit 24 may also determine whether the deviation condition is met when the forklift 1 is traveling downhill using a fade warning threshold that is greater than the fade warning threshold Th2 (the absolute value of the negative slope is small).

[0071] In the above embodiment, an example of a deceleration acquisition unit that acquires the deceleration of the forklift 1 was shown, which calculates the deceleration (negative acceleration) from the vehicle speed detected by the vehicle speed sensor 5a. However, the embodiment is not limited to this example. For example, the deceleration acquisition unit may be an acceleration sensor that at least detects the acceleration of the forklift 1 in the longitudinal direction.

[0072] In the above embodiment, as an example, the evaluation value calculation unit 23 calculates an evaluation value obtained by dividing the brake output by the brake input and the rate of change of the evaluation value, but it is not limited to this example. The evaluation value calculation unit may calculate either the evaluation value or the rate of change of the evaluation value, or it may calculate an index different from the evaluation value and the rate of change of the evaluation value, and the notification control unit 24 may use this index to evaluate whether or not the drum brake 18 is ineffective. The different index may be, for example, an index obtained by dividing the brake input by the brake output. In this case, the relationship between the index and a predetermined threshold (direction of the inequality sign) will be the opposite of that in the above embodiment. The different index may also be, for example, the difference in brake output from brake input. In this case, the relationship between the index and a predetermined threshold may be the same as in the above embodiment.

[0073] In the above embodiment, the notification control unit 24 used the calculated evaluation value, but it is also possible to determine whether a certain deviation condition is met when there is a discrepancy between the brake output and the brake input by directly using the brake input, brake output and a predetermined threshold value, without going through the evaluation value.

[0074] In the above embodiment, the temperature threshold Thx, the fade determination threshold Th1, and the fade warning threshold Th2 were pre-set parameters, but a map containing multiple values ​​may also be pre-set.

[0075] In the above embodiment, the industrial vehicle notification device 100 is mounted on an electric forklift 1 powered by the battery 9, but it can also be applied to forklifts powered by an engine or fuel cell.

[0076] In the above embodiment, the industrial vehicle notification device 100 is mounted on the forklift 1, but it can also be applied to industrial vehicles other than forklifts (for example, towing tractors, etc.). In short, any industrial vehicle equipped with hydraulic drum brakes that brake the wheels of the industrial vehicle by the brake operation of the industrial vehicle's occupant is acceptable, and it may also be an industrial vehicle that has disc brakes in addition to drum brakes.

[0077] The constituent elements of various embodiments of the present invention are described below. <Invention 1> An industrial vehicle notification device equipped with a hydraulic drum brake that brakes the wheels of the industrial vehicle by the brake operation of the occupant of the industrial vehicle, A hydraulic pressure acquisition unit that acquires the hydraulic pressure applied to the drum brake, A deceleration acquisition unit that acquires the deceleration of the aforementioned industrial vehicle, An input calculation unit calculates a brake input corresponding to the braking torque corresponding to the hydraulic pressure, based on the hydraulic pressure and the specifications of the drum brake, An output calculation unit calculates a brake output corresponding to the braking torque that corresponds to the deceleration, based on the deceleration and the specifications of the industrial vehicle. An industrial vehicle notification device comprising: a notification control unit that determines whether a certain deviation condition is met when there is a discrepancy between the brake output and the brake input based on the brake input, the brake output and a predetermined threshold; and, if it is determined that the discrepancy condition is met, notifies the occupant that there is insufficient effectiveness of the drum brake in response to the brake operation. <Invention 2> The system includes an evaluation value calculation unit that calculates an evaluation value obtained by dividing the brake output by the brake input, The notification control unit determines that the deviation condition is met when the evaluation value is less than or equal to the first threshold, as described in Invention 1, for the notification device for an industrial vehicle. <Invention 3> The drum brake is equipped with a temperature acquisition unit that acquires the lining temperature, The notification control unit determines that the deviation condition is met when the lining temperature is above a predetermined temperature threshold and the evaluation value is below the first threshold, and notifies the occupant that a fade phenomenon is occurring in the drum brake, as described in Invention 2. <Invention 4> An evaluation value calculation unit that calculates the rate of change of an evaluation value obtained by dividing the brake output by the brake input, The drum brake is equipped with a temperature acquisition unit that acquires the lining temperature of the drum brake, An industrial vehicle notification device according to any one of Inventions 1 to 3, wherein the notification control unit determines that the deviation condition is met when the lining temperature is above a predetermined temperature threshold and the rate of change of the evaluation value is below a second threshold, and notifies the occupant that a fade phenomenon is occurring in the drum brake. [Explanation of Symbols]

[0078] 5...Front wheel, 5a...Vehicle speed sensor (deceleration acquisition unit), 18...Drum brake, 18e...Lining temperature sensor (temperature acquisition unit), 18g...Brake hydraulic pressure sensor (hydraulic pressure acquisition unit), 21...Input calculation unit, 22...Output calculation unit, 23...Evaluation value calculation unit, 24...Notification control unit, 100...Notification device, d...Deceleration, P...Hydraulic pressure, Thx...Temperature threshold.

Claims

1. An industrial vehicle notification device equipped with a hydraulic drum brake that brakes the wheels of the industrial vehicle by the brake operation of the occupant of the industrial vehicle, A hydraulic pressure acquisition unit that acquires the hydraulic pressure applied to the drum brake, A deceleration acquisition unit that acquires the deceleration of the aforementioned industrial vehicle, An input calculation unit calculates the brake input based on the hydraulic pressure and the specifications of the drum brake for calculating the brake input corresponding to the braking torque corresponding to the hydraulic pressure, An output calculation unit calculates the brake output based on the deceleration and the specifications of the industrial vehicle for calculating the brake output corresponding to the braking torque corresponding to the deceleration, A notification control unit determines whether a certain deviation condition is met when there is a discrepancy between the brake output and the brake input, based on the brake input, the brake output, and a predetermined threshold, and if it is determined that the discrepancy condition is met, it notifies the occupant that the drum brake is not effective enough in response to the brake operation. The system includes an evaluation value calculation unit that divides the brake output by the brake input and calculates an evaluation value corresponding to the brake efficiency, An industrial vehicle notification device, wherein the notification control unit determines that the deviation condition is met when the evaluation value is less than or equal to the first threshold.

2. A load sensor is provided to detect the load of the cargo, The industrial vehicle notification device according to claim 1, wherein the output calculation unit calculates the brake output based on the mass of the industrial vehicle as a specification of the industrial vehicle, including the load of the cargo detected by the load sensor.

3. An industrial vehicle notification device equipped with a hydraulic drum brake that brakes the wheels of an industrial vehicle by the brake operation of an industrial vehicle occupant, A hydraulic pressure acquisition unit that acquires the hydraulic pressure applied to the drum brake, A deceleration acquisition unit that acquires the deceleration of the aforementioned industrial vehicle, An input calculation unit calculates the brake input based on the hydraulic pressure and the specifications of the drum brake for calculating the brake input corresponding to the braking torque corresponding to the hydraulic pressure, An output calculation unit calculates the brake output based on the deceleration and the specifications of the industrial vehicle for calculating the brake output corresponding to the braking torque corresponding to the deceleration, A notification control unit determines whether a certain deviation condition is met when there is a discrepancy between the brake output and the brake input, based on the brake input, the brake output, and a predetermined threshold, and if it is determined that the discrepancy condition is met, it notifies the occupant that the drum brake is not effective enough in response to the brake operation. An evaluation value calculation unit that calculates an evaluation value obtained by dividing the brake output by the brake input, The drum brake is equipped with a temperature acquisition unit that acquires the lining temperature of the drum brake, An industrial vehicle notification device wherein the notification control unit determines that the deviation condition is met when the lining temperature is above a predetermined temperature threshold and the evaluation value is below the first threshold, and notifies the occupant that a fade phenomenon is occurring in the drum brake.

4. An industrial vehicle notification device comprising a hydraulic drum brake that brakes the wheels of an industrial vehicle by the brake operation of an industrial vehicle occupant, A hydraulic pressure acquisition unit that acquires the hydraulic pressure applied to the drum brake, A deceleration acquisition unit that acquires the deceleration of the aforementioned industrial vehicle, An input calculation unit calculates the brake input based on the hydraulic pressure and the specifications of the drum brake for calculating the brake input corresponding to the braking torque corresponding to the hydraulic pressure, An output calculation unit calculates the brake output based on the deceleration and the specifications of the industrial vehicle for calculating the brake output corresponding to the braking torque corresponding to the deceleration, A notification control unit determines whether a certain deviation condition is met when there is a discrepancy between the brake output and the brake input, based on the brake input, the brake output, and a predetermined threshold, and if it is determined that the discrepancy condition is met, it notifies the occupant that the drum brake is not effective enough in response to the brake operation. An evaluation value calculation unit that calculates the rate of change of an evaluation value obtained by dividing the brake output by the brake input, The drum brake is equipped with a temperature acquisition unit that acquires the lining temperature of the drum brake, An industrial vehicle notification device, wherein the notification control unit determines that the deviation condition is met when the lining temperature is above a predetermined temperature threshold and the rate of change of the evaluation value is below a second threshold, and notifies the occupant that a fade phenomenon is occurring in the drum brake.

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