Brake mechanism for construction vehicles

Abstract

To provide a brake mechanism of a construction vehicle capable of avoiding a collision due to a human error with a simple structure.SOLUTION: A construction vehicle in which a drum brake DB is operated by stepping on a brake pedal 15 comprises: a hydraulic mechanism which is provided with an interposition of a solenoid valve (first selector valve) V10 provided in a first flow channel 209; and a control part which, when an obstruction is detected by an obstruction detection device, communicates the hydraulic mechanism with the drum brake DB by switching the solenoid valve (first selector valve) V10 and operates the drum brake DB through pressurization of the hydraulic mechanism.SELECTED DRAWING: Figure 30

Description

[Technical field]

[0001] The present invention relates to a brake mechanism for a construction vehicle. [Background technology]

[0002] For example, Patent Document 1 discloses a brake mechanism for a construction vehicle. In the construction vehicle of Patent Document 1, the operator operates a hydrostatic transmission (HST) brake to brake the vehicle by returning a forward / reverse lever provided in the driver's seat from a forward or reverse position to a neutral position. In addition, in the construction vehicle of Patent Document 1, the brake pedal and the forward / reverse lever are connected via a base plate and multiple rods, so that the forward / reverse lever can be returned to the neutral position by depressing the brake pedal, thereby braking the vehicle.

[0003] In addition, the brake mechanism of another construction vehicle has a master cylinder provided behind the brake pedal and a drum brake that is actuated by the master cylinder. In this brake mechanism, the brakes can be actuated via the master cylinder when the operator depresses the brake pedal. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 61-16930 Summary of the Invention [Problem to be solved by the invention]

[0005] While driving and working, trained operators check the surroundings by looking directly at objects or indirectly through the mirrors. When the operator senses danger, he or she can prevent a collision by braking the construction vehicle by operating the forward / reverse lever or stepping on the brake pedal. However, there is a problem that collisions occur due to human error caused by operators' disregard for danger or habituation.

[0006] Therefore, an object of the present invention is to provide a brake mechanism for a construction vehicle that can avoid collision accidents caused by human error with a simple structure. [Means for solving the problem]

[0007] The brake mechanism of a construction vehicle of the present invention is a construction vehicle comprising an obstacle detection device which detects obstacles around the construction vehicle, a brake pedal provided at a driver's seat, a first actuator which is actuated by depression of the brake pedal, a drum brake which is actuated by the first actuator, and a first flow path which connects the first actuator and the drum brake and through which hydraulic oil flows, and in which the drum brake is actuated by depression of the brake pedal, the construction vehicle further comprising a hydraulic mechanism provided via a first switching valve provided in the first flow path, and a control unit which, when an obstacle is detected by the obstacle detection device, switches the first switching valve to communicate between the hydraulic mechanism and the drum brake, and actuates the drum brake by pressurizing the hydraulic mechanism. The vehicle is characterized in that an oil passage T1 and an oil passage T2 for operating a swash plate are connected to a traveling pump that drives the construction vehicle, a second switching valve is provided for switching the flow direction of hydraulic oil in the oil passage T1 and the oil passage T2, and a switch is provided that is operated by depressing the brake pedal, and the second switching valve is switched by the switch to equalize the pressure between the oil passage T1 and the oil passage T2 and operate the HST brake.

[0008] According to the present invention, the drum brakes can be activated via the hydraulic mechanism and the first switching valve upon detection of an obstacle, even without the brake pedal being depressed, making it possible to avoid collision accidents caused by human error with a simple structure. Furthermore, according to the present invention, when the brake pedal is depressed, the HST brake can be actuated in addition to the drum brake, so that braking can be performed reliably.

[0009] In addition, it is preferable that the hydraulic mechanism includes a second actuator provided on the construction vehicle, a third actuator operated by the second actuator, and a second flow path connecting the third actuator and the first switching valve provided in the first flow path and through which hydraulic oil flows, and when an obstacle is detected by the obstacle detection device, the first switching valve is switched to connect the second flow path to the drum brake, and the second actuator is operated and the drum brake is operated by pressurizing the third actuator.

[0010] According to the present invention, the hydraulic mechanism can be configured with a simple structure. Effect of the Invention

[0013] According to the present invention, collision accidents caused by human error can be avoided with a simple structure. [Brief description of the drawings]

[0014] [Figure 1] 1A and 1B are a plan view and a side view, respectively, of a brake mechanism for a construction vehicle according to a first embodiment of the present invention. [Diagram 2] 2 is a schematic view of a main part of a brake mechanism of the construction vehicle according to the first embodiment. FIG. [Diagram 3] FIG. 3 is a view taken along the line III-III in FIG. 2. [Figure 4] FIG. 4 is a view taken along the line IV-IV in FIG. [Diagram 5] 13 is a diagram illustrating the operation of the base plate and the surrounding area when the forward / reverse lever is tilted to the maximum in the forward direction. FIG. [Figure 6] 13 is a diagram illustrating the operation of the base plate and the surrounding area when the forward / reverse lever is tilted to the maximum in the reverse direction. FIG. [Figure 7] 6 is a diagram illustrating the operation of the base plate and its surroundings when the brake pedal is depressed. [Figure 8] FIG. 2 is a block diagram of a brake mechanism of the construction vehicle according to the first embodiment. [Figure 9] FIG. 2 is a schematic diagram of a hydraulic circuit according to the first embodiment. [Figure 10] FIG. 3 is a view taken along the arrow XX in FIG. 2. [Figure 11] FIG. 11 is a side view of a main portion of a brake mechanism of a construction vehicle according to a second embodiment of the present invention. [Figure 12] FIG. 11 is a side view of a main portion of a brake mechanism of a construction vehicle according to a third embodiment of the present invention. [Figure 13A] FIG. 11 is an enlarged perspective view of a base member according to a third embodiment. [Figure 13B] FIG. 13 is an enlarged side view of a base member according to a modified example of the third embodiment. [Figure 13C] FIG. 13 is an enlarged side view of a base member according to a modified example of the third embodiment. [Figure 14] FIG. 13 is a side view of a main portion of a brake mechanism of a construction vehicle according to a fourth embodiment of the present invention. [Figure 15] FIG. 13 is a side view of a main portion of a brake mechanism of a construction vehicle according to a fifth embodiment of the present invention. [Figure 16] FIG. 13 is a side view of a main portion of a brake mechanism of a construction vehicle according to a sixth embodiment of the present invention. [Figure 17] FIG. 13 is a schematic view of a main portion of a brake mechanism of a construction vehicle according to a seventh embodiment of the present invention. [Figure 18] FIG. 13 is a side view of a main part according to the seventh embodiment. [Figure 19] 19 is an operational diagram showing the case where the forward / reverse lever in FIG. 18 is tilted to the maximum in the forward direction. [Figure 20] 19 is an operational diagram showing the case where the forward / reverse lever in FIG. 18 is tilted to the maximum in the reverse direction. [Figure 21] 19 is an operational diagram showing a case where the actuator in FIG. 18 is operated. FIG. [Figure 22] FIG. 13 is a schematic view of a main part of a brake mechanism of a construction vehicle according to an eighth embodiment of the present invention. [Figure 23] XXIII-XXIII in Figure 22. [Figure 24] FIG. 13 is a schematic view of a main part of a brake mechanism of a construction vehicle according to a ninth embodiment of the present invention. [Diagram 25]FIG. 13 is a side view of a main portion of a brake mechanism of a construction vehicle according to a ninth embodiment. [Figure 26] FIG. 13 is a schematic diagram of a main part of a brake mechanism of a construction vehicle according to a tenth embodiment of the present invention. [Figure 27] FIG. 13 is a schematic hydraulic circuit diagram of a brake mechanism of a construction vehicle according to a tenth embodiment. [Figure 28] FIG. 23 is a schematic diagram of a main part of a brake mechanism of a construction vehicle according to an eleventh embodiment of the present invention. [Figure 29] FIG. 23 is a schematic diagram of a main part of a brake mechanism of a construction vehicle according to a twelfth embodiment of the present invention. [Diagram 30] FIG. 26 is a schematic hydraulic circuit diagram of a brake mechanism of a construction vehicle according to a twelfth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] [First embodiment] A brake mechanism 1 for a construction vehicle according to a first embodiment of the present invention will be described in detail with reference to the drawings. In FIG. 1, the brake mechanism 1 for a construction vehicle according to this embodiment is mounted on a construction vehicle such as a compaction roller that performs work while traveling at a low speed. In this embodiment, a compaction roller is illustrated, but the present invention may also be applied to other construction vehicles. Note that the following "up and down," "front and back," and "left and right" follow the arrows in FIG. 1.

[0016] 1 shows a case where a brake mechanism 1 for a construction vehicle is mounted on a rolling roller 10 that rolls asphalt road surfaces with rollers 11A and tires 11B. The rolling roller 10 includes a driver's seat 12, a dashboard 13, a steering wheel 14, a brake pedal 15, and a forward / reverse lever 16.

[0017] The driver's seat 12 is where the operator sits, and faces the dashboard 13. The dashboard 13 is a box-shaped body installed in front of the driver's seat, and various instruments, buttons, knobs, etc. are arranged on the upper surface. The handle 14 is a device for determining the traveling direction of the vehicle, and is provided on the upper surface of the dashboard 13.

[0018] The steering wheel 14 is connected to an Orbitroll (registered trademark, the same applies below; see FIG. 10) 14a provided inside an upper surface 13c (see FIG. 10) of the dashboard 13. The Orbitroll 14a is a hydraulic motor that constitutes part of the steering device. The Orbitroll 14a is supplied with hydraulic oil via a pipe 14b that is connected to a hydraulic circuit (not shown).

[0019] 1, the brake pedal 15 is provided under the dashboard 13 and configured to apply the brakes when the operator steps on it. The forward / reverse lever 16 is provided on both sides of the dashboard 13 and is a lever that can be tilted to a neutral position, a forward position, and a reverse position. The forward / reverse lever 16 may be configured to be provided on only one side of the dashboard 13.

[0020] As shown in Fig. 2, the forward / reverse levers 16, 16 are vertically connected to both ends of a shaft 17. The shaft 17 is arranged inside the dashboard 13 along the width direction. As shown in Figs. 2 and 3, a plate-shaped rotating plate 18 that rotates in sync with the shaft 17 is fixed vertically through the shaft 17. A connecting fulcrum portion 18b is formed at an end of a main body portion 18a of the rotating plate 18. A first cable 19 is connected to the connecting fulcrum portion 18b by a pin connection. One end of the first cable 19 is connected to the connecting fulcrum portion 18b, and the other end is connected to a forward / reverse switching lever (not shown) of the travel pump P (see Fig. 9).

[0021] As shown in Figs. 2 and 3, when the forward / reverse lever 16 is pushed to the forward position, the roller 10 moves forward, when the lever is pushed to the reverse position, the roller 10 moves backward, and when the lever is returned to the neutral position, the roller 10 is braked. That is, when the lever 16 is pushed to the forward position, the rotating plate 18 rotates upward about the axis of the shaft 17 and pulls the first cable 19. This causes the forward / reverse switching lever to rotate to the forward position and the roller 10 moves forward. On the other hand, when the lever 16 is pushed to the reverse position, the rotating plate 18 rotates downward about the axis of the shaft 17 and pushes the first cable 19. This causes the switching lever to rotate to the reverse position and the roller 10 moves backward. Also, when the lever 16 is returned to the neutral position, the HST brake described later is activated and the roller 10 is braked.

[0022] The brake pedal 15 is configured to move in conjunction with the shaft 17, as shown in Figures 2 and 4. A plate-shaped base plate 22 that rotates in synchronization with the shaft 17 is fixed vertically through the shaft 17. The base plate 22 is formed with a first pin 22a that is provided vertically on the rear left side surface and a second pin 22b that is provided vertically on the front right side surface. The first pin 22a and the second pin 22b are disposed at approximately the same distance from the shaft 17. The brake pedal 15 includes a main body plate 15a, a pedal portion 15b, a rotation fulcrum portion 15c, and a connecting fulcrum portion 15d.

[0023] The main body plate 15a is a plate-like member having a pedal portion 15b at the rear. The front end of the main body plate 15a is rotatably fixed via a bracket BK fixed to the front wall 13a of the dashboard 13. The rotation fulcrum portion 15c is the rotation center of the brake pedal 15. The connecting fulcrum portion 15d is formed at the upper center of the main body plate 15a.

[0024] The connecting fulcrum portion 15d is connected to the base plate 22 via a first brake pedal rod 23 and a second brake pedal rod 24. The first brake pedal rod 23 and the second brake pedal rod 24 are rod-shaped members. The lower ends of the first brake pedal rod 23 and the second brake pedal rod 24 are connected to the connecting fulcrum portion 15d by pin connection.

[0025] An elongated hole 23a into which the first pin 22a fits loosely is formed at the upper end of the first brake pedal rod 23. An elongated hole 24a into which the second pin 22b fits loosely is formed at the upper end of the second brake pedal rod 24. When viewed from the side, the first brake pedal rod 23 and the second brake pedal rod 24 are V-shaped.

[0026] In the initial position (when the forward / reverse lever 16 is in the neutral position), the base plate 22 is generally horizontal. The first pin 22a and the second pin 22b are located slightly above the center in the height direction of the long holes 23a and 24a.

[0027] Fig. 5 is an action diagram around the base plate 22 when the forward / reverse lever 16 is tilted to the maximum in the forward direction. As shown in Fig. 5, when the forward / reverse lever 16 is tilted in the forward direction, the shaft 17 and the base plate 22 rotate counterclockwise around the shaft 17. At this time, the first pin 22a is located at the upper end of the long hole 23a of the first brake pedal rod 23. On the other hand, the second pin 22b is located slightly below the center in the height direction of the long hole 24a of the second brake pedal rod 24. Even if the forward / reverse lever 16 is tilted in the forward direction, the position of the brake pedal 15 does not change because the first pin 22a and the second pin 22b move within the long holes 23a, 24a.

[0028] Fig. 6 is an action diagram around the base plate 22 when the forward / reverse lever 16 is tilted to the maximum in the reverse direction. As shown in Fig. 6, when the forward / reverse lever 16 is tilted in the reverse direction, the shaft 17 and the base plate 22 rotate clockwise around the shaft 17. At this time, the second pin 22b is located at the upper end of the long hole 24a of the second brake pedal rod 24. On the other hand, the first pin 22a is located slightly below the center in the height direction of the long hole 23a of the first brake pedal rod 23. Even if the forward / reverse lever 16 is tilted in the reverse direction, the position of the brake pedal 15 does not change because the first pin 22a and the second pin 22b move within the long holes 23a, 24a.

[0029] Fig. 7 is an action diagram around the base plate 22 when the brake pedal is depressed. As shown in Fig. 7, when the operator depresses the brake pedal 15, the brake pedal 15 rotates downward around the rotation fulcrum 15c. As a result, the first brake pedal rod 23 and the second brake pedal rod 24 are pulled downward, so that the first pin 22a and the second pin 22b are positioned at the upper ends of the long holes 23a and 24a, respectively, and the base plate 22 rotates at a predetermined angle and becomes approximately horizontal. In synchronization with this, the shaft 17 and the rotating plate 18 also rotate and are positioned in the neutral position, so that the HST brake is activated and braking is performed.

[0030] As described above, the operator can brake the compaction roller 10 by returning the forward / reverse lever 16 to the neutral position, or by depressing the brake pedal 15 to return the forward / reverse lever 16 to the neutral position. In other words, the above-mentioned configuration is a braking means operated by the operator.

[0031] Next, the brake means 6 (6A, 6B) operated by the control device (control section) 3 will be described.

[0032] Fig. 8 is a block diagram of the brake mechanism of the construction vehicle according to the first embodiment. As shown in Fig. 1 and Fig. 8, the brake mechanism 1 of the construction vehicle includes a TOF (Time Of Flight) type distance image sensor (3D distance sensor) 2 that measures distance from the time difference between projected light and reflected light, and a control device (controller) 3 (see Fig. 8) that determines the presence or absence of an obstacle G based on the measurement data of the distance image sensor 2. The obstacle G is, for example, a structure such as a pillar or a wall, or a person.

[0033] The distance image sensor (obstacle detection device) 2 includes a light-emitting unit that emits projected light such as infrared light, and a light-receiving unit that receives the reflected light when the projected light hits an object. The distance to the object is measured by measuring the time from when the infrared light is sent from the light-emitting unit to when the reflected light is received by the light-receiving unit. The projection angle from the distance image sensor 2 is, for example, 95° in the horizontal direction and 32° in the vertical direction (symbol θ1 shown in FIG. 1(b)), and the projection cross section has a horizontally elongated rectangular shape. The image resolution is, for example, 64 pixels in the horizontal direction and 16 pixels in the vertical direction, totaling 1024 pixels. The distance image sensor 2 is attached to the center of the vehicle width direction at the rear of the rolling roller 10 so that the projected light is projected diagonally downward in the backward direction.

[0034] Regarding the detection range of the obstacle G, if the projection range of the projected light is set as the detection range as it is, that is, if the dimension L1 (FIG. 1(a)) in the vehicle width direction is set wider than the vehicle width dimension of the compaction roller 10, the obstacle G will be recognized even though there is no risk of collision, and the vehicle will stop unnecessarily. Therefore, in this embodiment, the dimension L1 of the detection range 4 in the vehicle width direction (shown by diagonal lines in FIG. 1) is set to be approximately the same as the vehicle width dimension of the compaction roller 10. Since the distance image sensor 2 can measure the distance to the obstacle G, the control device 3 can determine whether or not the obstacle G is present in the detection range 4 set to the vehicle width dimension from the measurement data for each pixel, specifically, the distance between the distance image sensor 2 and the obstacle G in the vehicle width direction. By using the distance image sensor 2 in this way, the dimension L1 of the detection range 4 can be ensured to be constant over the front-rear direction of the vehicle. That is, the detection range 4 can be easily set to an approximately rectangular range with one side having the dimension L1 in a plan view as shown in FIG. 1(a). A dimension L2 of the detection range 4 in the vehicle longitudinal direction is appropriately set according to the usual running speed, and in this embodiment is set to, for example, about 3 meters.

[0035] In addition, since the projection light of the distance image sensor 2 is projected obliquely downward in the backward travel direction, the lateral angle θ2 of the projection light in a plan view is greater than 95°. Therefore, the distance L3 in the vehicle front-rear direction of the non-detection ranges 5, 5 formed between the detection range 4 and both rear ends of the compaction roller 10 can be kept small. In other words, the non-detection blind spots formed on both sides of the rear of the vehicle can be reduced.

[0036] As shown in Fig. 9, the control device (control unit) 3 is provided with a brake means 6A that applies the brakes to the vehicle when it is determined that an obstacle G is present within the detection range 4. A travel pump P driven by an engine (not shown) and a travel motor M that rotates the rollers 11A and tires 11B (Fig. 1) are connected in series to form a hydraulic closed circuit U1. The travel pump P is a swash plate type pump. An oil passage T1 and an oil passage T2 for operating the swash plate are connected to the travel pump P. A two-position three-port solenoid valve (second switching valve) V1 is provided in parallel with the travel pump P between the oil passage T1 and the oil passage T2.

[0037] When the engine is running, the solenoid valve V1 is in the right position in FIG. 9, and the oil passage T1 and the oil passage T2 are not connected to each other. Therefore, when the engine is running, tilting the forward / reverse lever 16 around the driver's seat to the forward position side causes the swash plate hydraulic oil to flow from the oil passage T1 side to the oil passage T2 side, and the swash plate tilts to one side. As a result, pressure oil flows in one direction in the closed circuit U1, the traveling motor M rotates in one direction, and the vehicle moves forward. When the forward / reverse lever 16 is tilted to the reverse position side, the swash plate hydraulic oil flows from the oil passage T2 side to the oil passage T1 side, and the swash plate tilts to the other side. As a result, pressure oil flows in the other direction in the closed circuit UI, the traveling motor M rotates in the other direction, and the vehicle moves backward.

[0038] When the engine is not running, the solenoid valve V1 is in the left position as shown in Figure 9, and the oil passages T1 and T2 are in communication. A hydraulic closed circuit U2 is formed between the solenoid valve V1 and the travel pump P, and no pressure difference occurs between the oil passages T1 and T2, so the swash plate is in the neutral position. This causes the HST (Hydro Static Transmission) brake to act in the closed circuit U1.

[0039] The braking means 6A of this embodiment utilizes this electromagnetic valve V1, and when an obstacle is detected during reverse travel, the control device 3 outputs a brake signal to switch the electromagnetic valve V1 from the right position to the left position. As a result, even if the engine is running and the forward / reverse lever remains tilted toward the reverse position, the swash plate is positioned in the neutral position, and the HST brake is applied in the closed circuit U1 to stop the traveling motor M. Note that a solenoid valve V2 for operating the negative brake M1 during parking is provided between the charge pump P1 built into the traveling pump P and the negative brake M1 built into the traveling motor M.

[0040] It is preferable that the timing from when the control device 3 determines that there is an obstacle G until when it outputs a brake signal, that is, the timing when the braking means 6A starts braking, is changed according to the traveling speed of the vehicle. For example, the control device 3 compares a brake start distance preset according to the traveling speed with the distance to the obstacle G present in the detection range 4 measured by the distance image sensor 2, and outputs a brake signal to the electromagnetic valve V1 when the distance to the obstacle G becomes equal to or shorter than the brake start distance.

[0041] The braking start distance is preferably set to a distance with a slight margin from the vehicle's actual measured limit braking distance, for example. The braking start distance is set to approximately 0.5 m at 2 km / h, approximately 1 m at 4 km / h, approximately 1.6 m at 6 km / h, and approximately 2.4 m at 8 km / h. Note that the vehicle speed sensor 7 (FIG. 8) that detects the vehicle's traveling speed may be a proximity sensor such as a rotary encoder that detects the number of tire rotations.

[0042] In this embodiment, as shown in Fig. 8, the control device (controller) 3 includes a brake means 6B that applies the brakes to the vehicle when it is determined that an obstacle G is present within the detection range 4. As shown in Fig. 10, the brake means 6B includes an actuator 30, a link plate 31, a base member 32, a first link rod 33, and a second link rod 34.

[0043] The actuator 30 is a device that operates the output shaft 30a in the height direction based on a brake signal from the control device 3. The actuator 30 can be various cylinders such as an air cylinder or an electric cylinder, but in this embodiment, a hydraulic cylinder is used. The actuator 30 can be set anywhere on the vehicle body, but in this embodiment, it is installed on the front surface of the front wall 13a of the dashboard 13 via a bracket BK. The actuator 30 is connected to a hydraulic circuit provided inside the vehicle via piping (not shown).

[0044] The link plate 31 is a plate-like member that connects the actuator 30 to the first link rod 33 and the second link rod 34. The link plate 31 includes a main body portion 31a, a fixed fulcrum portion 31b, a connecting fulcrum portion 31c, and a connecting fulcrum portion 31d. The main body portion 31a is disposed by being inserted through an opening 13d formed in the front wall 13a of the dashboard 13.

[0045] The fixed fulcrum 31b is provided on the upper part of the main body 31a and is rotatably fixed to the front surface of the front wall 13a via a bracket BK. The connecting fulcrum 31c is provided on the front end part of the main body 31a and is connected to the tip of the output shaft 30a of the actuator 30 by a pin connection. The connecting fulcrum 31d is provided on the upper part of the rear end part of the main body 31a and is connected to the lower ends of the first link rod 33 and the second link rod 34 by pin connections.

[0046] The base member 32 is a plate-like member that rotates in synchronization with the shaft 17. The base member 32 is fixed to the shaft 17 while perpendicularly penetrating the shaft 17. The base member 32 is formed with a first pin 32a that is vertically provided on the rear left side surface and a second pin 32b that is vertically provided on the front right side surface. The first pin 32a and the second pin 32b are disposed at approximately the same distance from the shaft 17.

[0047] The first link rod 33 is a rod-shaped member that connects the connection fulcrum portion 31d and the first pin 32a. An elongated hole 33a into which the first pin 32a fits loosely is formed at the upper end of the first link rod 33. An elongated hole 34a into which the second pin 32b fits loosely is formed at the upper end of the second link rod 34. When viewed from the side, the first link rod 33 and the second link rod 34 are V-shaped.

[0048] In the initial position (when the forward / reverse lever 16 is in the neutral position), the base member 32 is generally horizontal. The first pin 32a and the second pin 32b are located slightly above the center in the height direction of the long holes 33a and 34a.

[0049] When the forward / reverse lever 16 is tilted to move forward or backward, the first pin 32a and the second pin 32b move within the elongated holes 33a, 34a, respectively, as the shaft 17 and the base member 32 rotate, in the same manner as in the braking by the brake pedal 15 described above. In other words, as the forward / reverse lever 16 is tilted, the first pin 32a and the second pin 32b move within the elongated holes 33a, 34a, and the position of the link plate 31 does not change.

[0050] On the other hand, for example, when an obstacle G is detected by the distance image sensor 2 while moving backward, the control device 3 outputs a brake signal to operate the actuator 30. When the output shaft 30a of the actuator 30 is pulled, the rear end side of the link plate 31 rotates downward around the fixed fulcrum part 31b. As a result, the first link rod 33 and the second link rod 34 are pulled downward, so that the first pin 32a and the second pin 32b are positioned at the upper ends of the long holes 33a and 34a, respectively, and the base member 32 rotates by a predetermined angle and becomes approximately horizontal. In synchronization with this, the shaft 17 and the rotating plate 18 also rotate and are positioned in the neutral position, so that the HST brake is activated to brake.

[0051] After the forward / reverse lever 16 is returned to the neutral position by the brake means 6B, the actuator 30 is operated to extend the output shaft 30a to its original position, thereby returning it to the initial position (the state in FIG. 10).

[0052] According to the brake mechanism 1 of the construction vehicle of this embodiment described above, since it is equipped with the brake means 6B, the forward / reverse lever 16 can be automatically returned to neutral upon detection by the distance image sensor (obstacle detection device) 2, and the HST brake can be activated, and collision accidents due to human error can be avoided with a simple structure.

[0053] Furthermore, according to this embodiment, the output shaft 30a of the actuator 30 is connected to the base member 32 by a link mechanism including the link plate 31, the first link rod 33, and the second link rod 34, so that a simple structure can be achieved. Also, the brake means 6B can be attached to an existing compaction roller 10.

[0054] In addition, since the first pin 32a and the second pin 32b are movable through the long holes 33a, 34a, normal forward and reverse movement is not affected by the actuator 30 and the link plate 31.

[0055] In addition, since this embodiment is equipped with both braking means 6A, 6B, it is possible to operate both the brake of the solenoid valve V1 system and the brake of the actuator 30 system, thereby more reliably braking the compaction roller 10. In this embodiment, both the brake means 6A and 6B are provided, but the brake means 6A may not be provided.

[0056] [Second embodiment] Next, a brake mechanism 1A for a construction vehicle according to a second embodiment of the present invention will be described. As shown in Fig. 11, in the brake mechanism 1A for a construction vehicle according to the second embodiment, the brake means 6Ba is different from that of the first embodiment. In the second embodiment, the differences from the first embodiment will be mainly described.

[0057] The brake means 6Ba includes an actuator 30A, a link plate 31A, a base member 32, a first link rod 33, a second link rod 34, and a cable 37.

[0058] The actuator 30A is a device that operates the output shaft 30Aa based on a brake signal from the control device 3. The link plate 31A is a plate-like member having a substantially triangular shape. The link plate 31A includes a main body portion 31a, a fixed fulcrum portion 31b, a connecting fulcrum portion 31c, and a connecting fulcrum portion 31d. The main body portion 31a is disposed inside the dashboard 13.

[0059] The fixed fulcrum 31b is provided at the front end of the main body 31a and is rotatably fixed to the rear surface of the front wall 13a via a bracket BK. The connecting fulcrum 31c is provided at the lower center of the main body 31a and is connected to a cable 37 by a pin connection. One end of the cable 37 is connected to the connecting fulcrum 31c and the other end is connected to the output shaft 30Aa of the actuator 30A. The connecting fulcrum 31d is provided at the rear end of the main body 31a and is connected to the lower ends of the first link rod 33 and the second link rod 34 by pin connections.

[0060] For example, when an obstacle is detected by the distance image sensor 2 during reverse travel, the control device 3 outputs a brake signal to activate the actuator 30A. When the output shaft 30a of the actuator 30A pulls the cable 37, the rear end of the link plate 31A rotates downward around the fixed fulcrum 31b. As a result, the first link rod 33 and the second link rod 34 are pulled downward, so that the first pin 32a and the second pin 32b are positioned at the upper ends of the long holes 33a and 34a, respectively, and the base member 32 rotates at a predetermined angle and becomes approximately horizontal. In synchronization with this, the shaft 17 and the rotating plate 18 also rotate and are positioned in the neutral position, so that the HST brake is activated to apply braking.

[0061] The brake mechanism 1A for a construction vehicle according to the second embodiment described above can achieve substantially the same effects as the first embodiment. The actuator 30A of the brake means 6Ba may be provided anywhere within the compaction roller 10. As in this embodiment, the link plate 31A may be rotated via a cable 37. Using the cable 37 increases the degree of freedom in the installation position of the actuator 30A.

[0062] [Third embodiment] Next, a brake mechanism 1B for a construction vehicle according to a third embodiment will be described. As shown in Fig. 12, the brake mechanism 1B for a construction vehicle according to the third embodiment differs from the first embodiment in the brake means 6Bb. The third embodiment will be described mainly with respect to the parts that differ from the first embodiment.

[0063] The brake means 6Bb includes an actuator 30, a link plate 31, a base member 41, an engaging jig 42, and a connecting jig 43.

[0064] As shown in FIG. 12 and FIG. 13A, the base member 41 is a plate-like member that rotates in synchronization with the shaft 17. The base member 41 is fixed vertically to the shaft 17 through the shaft 17. The base member 41 includes a main body 41a, a first notch hole 41b, and a second notch hole 41c. The first notch hole 41b is formed in a substantially arc shape so as to be convex downward. The second notch hole 41c is formed below the center of the first notch hole 41b and continues to the first notch hole 41b. The second notch hole 41c is formed in a substantially semicircular shape so as to be convex downward. The first notch hole 41b has a sufficiently large opening relative to the second notch hole 41c.

[0065] The engagement jig 42 is a member that connects the base member 41 and the connecting jig 43, and in this embodiment, a clevis is used. The engagement jig 42 has a bifurcated main body portion 42a and a connector 42b that connects the tip ends of the main body portion 42a. The connector 43 is a rod-shaped member that connects the engagement jig 42 and the connecting fulcrum portion 31d. The engagement jig 42 is arranged so that the lower part of the base member 41 is rotatably inserted into the hollow portion formed by the main body portion 42a and the connector 42b. The engagement jig 42 is always upright, and the connector 42b is located inside the first notch 41b.

[0066] Here, the position directly below the axis of the shaft 17 and distance h away is defined as the setback center C1. The radius from the axis of the shaft 17 to the upper edge 41d of the first cutout hole 41b is defined as radius r1. The radius from the axis of the shaft 17 to the axis of the connector 42b is defined as radius r2. The radius from the setback center C1 to the lower edge 41e of the first cutout hole 41b is defined as radius r3.

[0067] In the initial position (when the forward / reverse lever 16 is in the neutral position), the connector 42b is located approximately in the center of the first notch 41b, as shown in Fig. 13A. When the forward / reverse lever 16 is switched to the forward position or the reverse position, the shaft 17 and the base member 41 rotate accordingly around the shaft 17. At this time, since the first notch 41b is formed, the base member 41 and the engaging jig 42 do not interfere with each other, allowing the base member 41 to rotate.

[0068] On the other hand, for example, when an obstacle G is detected by the distance image sensor 2 during reverse travel, the control device 3 outputs a brake signal to drive the actuator 30. When the output shaft 30a of the actuator 30 is pulled, the rear end side of the link plate 31 rotates downward around the fixed fulcrum portion 31b, and the engagement jig 42 is also pulled downward. As a result, the tilted base member 41 engages with the second cutout hole 41c while the connector 42b slides on the lower edge 41e of the first cutout hole 41b. Furthermore, the second cutout hole 41c is returned to the initial position by the engagement jig 42, so that the shaft 17 and the rotating plate 18 are located in the neutral position. As a result, the HST brake is activated to brake.

[0069] The brake mechanism 1B for a construction vehicle according to the third embodiment described above can achieve substantially the same effects as those of the first embodiment. Even if the base member 41 is used as in this embodiment, the actuator 30 of the brake means 6Bb can be operated to return the shaft 17 and the rotating plate 18 to the neutral position.

[0070] 13B and 13C are enlarged side views of a base member according to a modified example of the third embodiment. As shown in FIG. 13B, the second cutout hole may be omitted. In this modified example, the lower edge 41e of the first cutout hole 41b is pulled by the connector 42b of the engagement jig 42, so that the tilted base member 41 can be returned to the neutral position.

[0071] 13C, the shape of the second cutout hole 41c may be triangular in side view. By providing the second cutout hole 41c extending downward from the lowermost edge of the first cutout hole 41b as shown in Figs. 13A and 13C, the connector 42b of the engagement jig 42 can be easily engaged, so that the force for returning to the neutral position and the force for maintaining the neutral position (while the actuator 30 is operating) can be increased.

[0072] The second cutout hole 41c is not limited to the above shape, and may have other shapes as long as it can be engaged with or disengaged from the connector 42b. 13A to 13C, the setback center C1 of radius r3 may be offset by a distance h from the axis of the shaft 17, or, although not specifically shown, the radii r1, r2, and r3 may be concentric circles (distance h is zero). The first cutout hole 41b (second cutout hole 41c) and radii r1, r2, r3 may be appropriately set so that when the forward / reverse lever 16 is tilted, the base member 41 and the engaging jig 42 do not interfere with each other, allowing the base member 41 to rotate, and when the actuator 30 is activated, the engaging jig 42 can be pulled to return the tilted base member 41 to the neutral position.

[0073] As described above, even if the radii r1, r2, and r3 are concentric (the distance h is zero), this can be achieved if the second cutout hole 41c is sufficiently large. "Sufficiently large" means that the size and shape of the first cutout hole 41b and the second cutout hole 41c are determined so that the connector 42b is located below (outside the center) the arc drawn by the radius r3 when the connector 42b is pulled in the vertical direction when the base member 41 rotates to the front or rear and reaches the maximum tilt angle.

[0074] [Fourth embodiment] Next, a brake mechanism 1C for a construction vehicle according to a fourth embodiment of the present invention will be described. As shown in Fig. 14, in the brake mechanism 1C for a construction vehicle according to the fourth embodiment, the brake means 6Bc is different from that of the first embodiment. In the fourth embodiment, the differences from the first embodiment will be mainly described.

[0075] As described above, the orbit roll 14a is provided with the piping 14b connected to a hydraulic circuit (not shown). In this embodiment, the piping 14b is provided with the branch pipe 14c and the bypass pipe 14d. The branch pipe 14c and the bypass pipe 14d connect the piping 14b to the actuator 30. This allows the actuator 30, which is a hydraulic cylinder, to supply hydraulic oil to the actuator 30 by utilizing the existing piping 14b. This makes it possible to easily configure a hydraulic circuit according to this embodiment.

[0076] [Fifth embodiment] Next, a brake mechanism 1D for a construction vehicle according to a fifth embodiment of the present invention will be described. As shown in Fig. 15, in the brake mechanism 1D for a construction vehicle according to the fifth embodiment, the brake means 6Bd is different from that of the first embodiment. In the fifth embodiment, the differences from the first embodiment will be mainly described.

[0077] The brake means 6Bd includes an actuator 30, a link plate 31D, a base member 32, a first link rod 33, a second link rod 34, and a brake pedal rod 51. When the actuator 30 is operated, the brake means 6Bd rotates the base member 32 and also rotates the brake pedal 15D in conjunction with the rotation of the base member 32.

[0078] The front end of the brake pedal rod 51 is connected to the connection fulcrum 31e of the link plate 31D by a pin connection. A long hole 51a is formed on the rear end side of the brake pedal rod 51. An engagement pin 15e is vertically provided on the main body plate 15a of the brake pedal 15D. The engagement pin 15e is loosely fitted into the long hole 51a. The connection fulcrum 31e is located below and forward of the engagement pin 15e. The rear end of the brake pedal 15D is exposed to the outside through an opening 13e formed in the rear wall 13b of the dashboard 13.

[0079] When the operator depresses the brake pedal 15D, the base plate 22 (see FIG. 7) returns to the neutral position (horizontal) and the HST brake is activated to apply braking, as in the first embodiment. At this time, the engagement pin 15e of the brake pedal 15D moves forward within the elongated hole 51a, so that the link plate 31D does not rotate when the brake pedal 15D is depressed.

[0080] On the other hand, for example, when an obstacle is detected by the distance image sensor 2 while moving backward, the control device 3 outputs a brake signal to activate the actuator 30. This causes the base member 32 to become approximately horizontal in the same manner as in the first embodiment. In synchronization with this, the shaft 17 and the rotating plate 18 also rotate and are located in the neutral position, so that the HST brake is activated to brake. In addition, the link plate 31D rotates clockwise around the fixed fulcrum part 31b, so that the brake pedal rod 51 is pulled diagonally downward to the front side, and the brake pedal 15D is rotated in the actuating direction by the brake pedal rod 51.

[0081] As a result, the actuator 30 can be operated to operate the HST brakes even with the brake pedal 15 system, thereby performing braking. According to the fifth embodiment, one actuator 30 can link the link mechanism including the link plate 31D with the brake pedal 15D, so that the HST brakes can be operated with two systems, thereby performing braking more reliably.

[0082] [Sixth embodiment] Next, a brake mechanism 1E for a construction vehicle according to a sixth embodiment of the present invention will be described. As shown in Fig. 16, the brake mechanism 1E for a construction vehicle according to the sixth embodiment is a modified example of the second embodiment. In the brake mechanism 1E for a construction vehicle according to the sixth embodiment, the brake means 6Be is different from that of the second embodiment. The sixth embodiment will be described mainly with respect to the parts that differ from the second embodiment.

[0083] The brake means 6Be includes an actuator 30A, a link plate 31E, a base member 32, a first link rod 33, a second link rod 34, a cable 37, and a brake pedal rod 51. When the actuator 30A is operated, the brake means 6Be rotates the base member 32 and also rotates the brake pedal 15E in conjunction with the rotation of the base member 32.

[0084] The link plate 31E includes a main body 31a, a fixed fulcrum 31b, a connecting fulcrum 31c, a connecting fulcrum 31d, and a connecting fulcrum 31e. The fixed fulcrum 31b is provided on the front side of the main body 31a and is rotatably fixed to the rear surface of the front wall 13a via a bracket BK.

[0085] The connecting fulcrum portion 31c protrudes forward from the fixed fulcrum portion 31b and protrudes forward from an opening 13d in the front wall 13a. The connecting fulcrum portion 31c is connected to an end of a cable 37 by a pin connection.

[0086] The connecting fulcrum 31d is provided on the upper part of the main body 31a, and is connected to the lower ends of the first link rod 33 and the second link rod 34 by pin connections. The connecting fulcrum 31e is connected to the front end of the brake pedal rod 51 by pin connections. A long hole 51a is formed on the rear end side of the brake pedal rod 51. An engagement pin 15e formed on the brake pedal 15E is loosely fitted into the long hole 51a. The connecting fulcrum 31e is located below and in front of the engagement pin 15e. The rear end of the brake pedal 15E is exposed to the outside from an opening 13e formed in the rear wall 13b of the dashboard 13.

[0087] When the operator depresses the brake pedal 15E, the base plate 22 (see FIG. 7) returns to the neutral position (horizontal) and the HST brake is activated to apply braking, as in the first embodiment. At this time, the engagement pin 15e of the brake pedal 15E moves forward within the long hole 51a, so that the link plate 31E does not rotate when the brake pedal 15E is depressed.

[0088] On the other hand, for example, when an obstacle is detected by the distance image sensor 2 while reversing, the control device 3 outputs a brake signal to activate the actuator 30A. This causes the base member 32 to become approximately horizontal in the same manner as in the first embodiment. In synchronization with this, the shaft 17 and the rotating plate 18 also rotate to the neutral position, and the HST brake is activated to brake. In addition, the link plate 31E is pushed by the cable 37 and rotates clockwise around the fixed fulcrum part 31b. This causes the brake pedal rod 51 to be pulled diagonally downward to the front side, and the brake pedal 15E rotates in the actuating direction.

[0089] In other words, by operating the actuator 30A, the HST brake can be operated in the brake pedal 15E system as well to perform braking. According to the sixth embodiment, the single actuator 30A can link the link mechanism including the link plate 31E and the brake pedal 15E, so that the HST brake can be operated in two systems to perform braking more reliably.

[0090] [Seventh embodiment] Next, a brake mechanism 1F for a construction vehicle according to a seventh embodiment of the present invention will be described. As shown in Fig. 17, in the brake mechanism 1F for a construction vehicle according to the seventh embodiment, the brake means 6Bf is different from that of the first embodiment. In the seventh embodiment, the differences from the first embodiment will be mainly described.

[0091] As shown in FIGS. 17 and 18, the brake means 6Bf includes a rotating plate 18A, a connecting plate 61, a second cable 62, and an actuator 30A.

[0092] The rotating plate 18A is a plate-like member having a substantially triangular shape. A shaft 17 that rotates in synchronization with the rotating plate 18A is fixed vertically through the front part of the rotating plate 18A. The rotating plate 18A includes a main body 18a, a connecting fulcrum part 18b, and a connecting fulcrum part (connecting pin) 18c. The axis of the shaft 17, the connecting fulcrum part 18b, and the connecting fulcrum part 18c are provided near each corner of the triangle of the main body 18a. The connecting fulcrum part 18b is provided at the bottom of the main body 18a, and is a portion to which an end of the first cable 19 is connected by a pin connection.

[0093] The connection fulcrum (connection pin) 18c is provided on the upper part of the main body 18a, and is a portion to which the connection plate 61 is connected by a pin connection. The connection plate 61 is a rectangular plate-like member, and is a member that connects the rotating plate 18A and the second cable 62. A long hole 61a is formed in the connection plate 61. The second cable 62 is provided with a movable pin 63 at one end, and the other end is connected to the actuator 30A. The movable pin 63 is loosely fitted in the long hole 61a.

[0094] Fig. 19 is an operation diagram showing a case where the forward / reverse lever is tilted most in the forward direction in Fig. 18. As shown in Fig. 19, when the operator tilts the forward / reverse lever 16 in the forward direction, the rotating plate 18A rotates counterclockwise around the shaft 17. This pulls the first cable 19, and the forward / reverse switching lever (not shown) of the traveling pump P rotates to the forward position. At this time, the rotating plate 18A and the connecting plate 61 rotate relatively around the connecting fulcrum part 18c, and the movable pin 63 moves within the long hole 61a.

[0095] Fig. 20 is an operation diagram showing a case where the forward / reverse lever is tilted most in the reverse direction in Fig. 18. As shown in Fig. 19, when the operator tilts the forward / reverse lever 16 in the reverse direction, the rotating plate 18A rotates clockwise around the shaft 17. This pushes the first cable 19, and the forward / reverse switching lever (not shown) of the traveling pump P rotates to the reverse position. At this time, the rotating plate 18A and the connecting plate 61 rotate relatively around the connecting fulcrum part 18c, and the movable pin 63 moves within the long hole 61a.

[0096] In other words, even if the forward / reverse lever 16 is tilted in the forward or reverse direction, no load is applied to the actuator 30A because the connecting plate 61 and the elongated hole 61a are formed.

[0097] On the other hand, for example, when an obstacle is detected by the distance image sensor 2 while reversing, the control device 3 outputs a brake signal to activate the actuator 30A. As shown in Fig. 21, when the second cable 62 is pulled by the actuator 30A, the movable pin 63 moves to the end of the long hole 61a, and is further pulled by the second cable 62, causing the rotating plate 18A to rotate about the shaft 17 and return to the neutral position. This activates the HST brake to apply braking.

[0098] According to the brake mechanism 1F of the construction vehicle of this embodiment described above, since it is equipped with the brake means 6Bf, the forward / reverse lever 16 can be automatically returned to neutral upon detection by the distance image sensor (obstacle detection device) 2, and the HST brake can be activated, so that a collision accident due to human error can be avoided with a simple structure.

[0099] In addition, the connecting plate 61 has a connecting fulcrum portion (connecting pin) 18c that is rotatably connected to the rotating plate 18A, and a long hole 61a through which the movable pin 63 of the second cable 62 slides, so that the rotating plate 18A and the second cable 62 can be connected with a simple configuration.

[0100] The end of the long hole 61a on the second cable 62 side may be locally formed as a fine hole. This allows the movable pin 63 to be guided by the fine hole of the long hole 61a and to easily move to the end, thereby improving the responsiveness of the brake.

[0101] [Eighth embodiment] Next, a brake mechanism 1G for a construction vehicle according to an eighth embodiment of the present invention will be described. As shown in Fig. 22, in the brake mechanism 1G for a construction vehicle according to the eighth embodiment, the brake means 6Bg is different from that of the first embodiment. In the eighth embodiment, the differences from the first embodiment will be mainly described.

[0102] 22 and 23, the brake means 6Bg includes an actuator 30, a link plate 31, a base member 32, a first link rod 33, and a second link rod 34. The brake means of the actuator 30 system is the same as that of the first embodiment.

[0103] The brake means 6Bg includes a rotating plate 18A, a connecting plate 61, a second cable 62, and an actuator 30A. As shown in Fig. 22, the brake means of the actuator 30A system is the same as that of the seventh embodiment.

[0104] According to the brake mechanism 1G of the construction vehicle of this embodiment, for example, when an obstacle G is detected by the distance image sensor 2 while reversing, the control device 3 outputs a brake signal to activate both the actuator 30 and the actuator 30A. This makes it possible to more reliably activate the HST brake by the mechanisms of both the actuator 30 system and the actuator 30A system.

[0105] [Ninth embodiment] Next, a brake mechanism 1H of a construction vehicle according to a ninth embodiment will be described. As shown in Fig. 24 and Fig. 25, the brake mechanism 1H according to the ninth embodiment is equipped with a brake means 6Bh, and is obtained by adding a brake by a brake pedal 15 (third cable 65) system to the seventh embodiment. The ninth embodiment will be described mainly with respect to the parts that differ from the seventh embodiment.

[0106] The brake means 6Bh includes a rotating plate 18A, a connecting plate 61, a second cable 62, and an actuator 30A. The brake mechanism for the second cable 62 is the same as that in the seventh embodiment.

[0107] 24 and 25, the braking means 6Bh includes a third cable 65, a rotating plate 71, and a brake pedal rod 51. The braking means 6Bh operates the HST brakes in both the second cable 62 system and the third cable 65 system based on the actuator 30A.

[0108] The third cable 65 is a cable that connects the actuator 30A and the rotating plate 71. The rotating plate 71 is a plate-like member having a substantially triangular shape. The rotating plate 71 includes a main body portion 71a, a fixed fulcrum portion 71b, a connecting fulcrum portion 71c, and a connecting fulcrum portion 71d. The fixed fulcrum portion 71b, the connecting fulcrum portion 71c, and the connecting fulcrum portion 71d are provided near each corner of the triangle of the main body portion 71a. The fixed fulcrum portion 71b is a portion that is rotatably fixed via a bracket BK that is connected to a part of the vehicle.

[0109] The connecting fulcrum 71c is a portion to which an end of the third cable 65 is connected by a pin connection. The connecting fulcrum 71d is a portion to which a front end of the brake pedal rod 51 is connected by a pin connection. The rear end of the brake pedal rod 51 is loosely fitted into the engagement pin 15e of the brake pedal 15 via the long hole 51a.

[0110] As in the first embodiment, the shaft 17 and the rotating plate 18A return to the neutral position when the brake pedal 15 is depressed, and the HST brake is activated to brake. At this time, since the elongated hole 51a is provided in the brake pedal 15, the engagement pin 15e moves within the elongated hole 51a. In other words, the rotating plate 71 does not rotate when the brake pedal 15 is depressed.

[0111] On the other hand, for example, when an obstacle G is detected by the distance image sensor 2 during reverse travel, the control device 3 outputs a brake signal to drive the actuator 30A. The brake operation of the second cable 62 system is the same as in the seventh embodiment. When the output shaft 30Aa is pulled by driving the actuator 30A, the rotating plate 71 rotates clockwise around the fixed fulcrum part 71b via the third cable 65.

[0112] As a result, the brake pedal rod 51 is pulled diagonally downward toward the front side, causing the brake pedal 15 to rotate in the actuation direction of the brake pedal 15. This also activates the brake mechanism of the brake pedal 15 system, and the HST brake is actuated.

[0113] According to the ninth embodiment described above, a single actuator 30A can operate both the second cable 62 system and the third cable 65 (brake pedal 15) system, so that braking can be performed more reliably.

[0114] [Tenth embodiment] Next, a brake mechanism 1M of a construction vehicle according to a tenth embodiment will be described. As shown in Fig. 26, the brake mechanism 1M according to the tenth embodiment is equipped with a brake means 6Bk. In the tenth embodiment, the differences from the first embodiment will be mainly described.

[0115] The brake means 6Bk includes a first actuator 101, a second actuator 30A, and a first transmission mechanism Q1. The first actuator 101 can be, for example, any type of cylinder, and in this embodiment, a master cylinder is used. The first actuator 101 is fixed, for example, to the front surface of the front wall 13a of the dashboard 13 via a bracket BK.

[0116] The first actuator 101 includes a main body 102, a shaft portion 103 protruding from the main body 102, and an accessory member 104 attached to the shaft portion 103. The shaft portion 103 is inserted through an opening 13d in the front wall 13a. The accessory member 104 is a long, thin plate-like member and includes a long hole 104a that penetrates in the left-right direction.

[0117] As shown in FIG. 27, each tire 11B (for example, four tires in this embodiment) is provided with a drum brake DB. The first actuator 101 is connected to each drum brake DB via a flow path 111 through which pressure oil (hydraulic oil) flows. A brake fluid reserve tank RT is also connected to the first actuator 101. When an external force pushes the accessory member 104 forward, the first actuator 101 is actuated via the shaft portion 103, and the drum brake DB is expanded to apply the brake. The number of drum brakes DB may be appropriately set according to the number of tires 11B.

[0118] As shown in FIG. 26, the brake pedal 15 includes a main body plate 15a, a pedal portion 15b, a pivot portion 15c, and an auxiliary member 130. The auxiliary member 130 is a long and thin plate-like member. The auxiliary member 130 is fixed to the main body plate 15a and rotates in synchronization with the main body plate 15a. One end of the auxiliary member 130 is fixed to the main body plate 15a, and a movable pin 130a is provided on the other end of the auxiliary member 130. The movable pin 130a is slidable within an elongated hole 104a of the accessory member 104.

[0119] The first transmission mechanism Q1 is a mechanism that transmits the power of the second actuator 30A to the accessory member 104. The first transmission mechanism Q1 is composed of a cable 112 and a rotating member 121. The rotating member 121 is an elongated plate-like member. The rotating member 121 is rotatable about a fixed fulcrum part 121b provided in the center. A connecting fulcrum part 121a to which the cable 112 is connected by pin support is formed on one end side of the rotating member 121. A narrow tip part 121c is formed on the other end side of the rotating member 121.

[0120] In the initial position (when the forward / reverse lever 16 is in the neutral position), the movable pin 130a of the auxiliary member 130 is located slightly forward (to the left in FIG. 26) from the center of the long hole 104a of the accessory member 104. In addition, the rotating member 121 is generally parallel to the vertical direction.

[0121] When the operator depresses the brake pedal 15, the auxiliary member 130 rotates clockwise around the rotation fulcrum 15c together with the brake pedal 15. This causes the movable pin 130a to move forward (to the left in FIG. 26) and, after abutting against the wall of the long hole 104a, pushes the shaft portion 103 forward. This activates the first actuator 101 and expands the drum brake DB to activate the brake. When the brake pedal 15 is released, the brake pedal 15 returns to its original position due to a restoring force.

[0122] On the other hand, for example, when an obstacle G is detected by the distance image sensor 2 while the vehicle is moving backward, the control device 3 outputs a brake signal to drive the second actuator 30A. When the output shaft 30Aa is pulled by driving the second actuator 30A, the rotating member 121 rotates counterclockwise around the fixed fulcrum part 121b via the cable 112. As a result, the tip part 121c of the rotating member 121 abuts against the accessory member 104, and pushes the accessory member 104 forward (to the left in FIG. 26). As a result, the first actuator 101 is actuated, and the drum brake DB is expanded to actuate the brake. At this time, the movable pin 130a slides in the long hole 104a of the accessory member 104, and does not affect the brake pedal 15.

[0123] When the output shaft 30Aa of the actuator 30A returns to its original position, the rotating member 121 also rotates and returns to its original position via the cable 112. In addition, the accessory member 104 also returns to its original position due to the restoring force of the first actuator 101.

[0124] According to the brake mechanism 1M of the construction vehicle according to this embodiment, for example, when an obstacle G is detected by the distance image sensor 2 while the vehicle is moving backwards, the control device 3 outputs a brake signal to activate the second actuator 30A. This allows the first actuator (master cylinder) 101 to be activated via the second actuator 30A and the first transmission mechanism Q1 even if the operator does not depress the brake pedal 15. This allows the brakes to be applied by the drum brake DB.

[0125] Furthermore, according to this embodiment, the brake mechanism 1M for a construction vehicle can be formed with a simple structure.

[0126] [Eleventh embodiment] Next, a brake mechanism 1N for a construction vehicle according to an eleventh embodiment will be described. As shown in Fig. 28, the brake mechanism 1N for a construction vehicle according to the eleventh embodiment is equipped with a brake means 6Bm. The eleventh embodiment will be described mainly with respect to the parts that differ from the first embodiment.

[0127] The brake means 6Bm includes a switch SW, a second actuator 30A, and a second transmission mechanism Q2. The switch SW is electrically connected to an electromagnetic valve V2 shown in Fig. 9. When the switch SW is excited, the electromagnetic valve V2 is switched, and pressure oil (hydraulic oil) in a brake chamber in the traveling motor M is released, and the brake is activated (negative brake).

[0128] The brake pedal 15 includes a body plate 15a, a pedal portion 15b, a rotation fulcrum portion 15c, and an auxiliary member 131. The auxiliary member 131 is attached to the body plate 15a, and is provided so as to turn on (excite) a switch SW when the operator depresses the brake pedal 15.

[0129] The second transmission mechanism Q2 is a mechanism that transmits the power of the second actuator 30A to the switch SW. The second transmission mechanism Q2 includes an intermediate member 122 and a cable 112. The intermediate member 122 is a long and thin plate-like member, and is disposed parallel to the vertical direction. One end of the intermediate member 122 is connected to the cable 112 via a connection fulcrum portion 122a. A long hole 122b is formed in the intermediate member 122 along the longitudinal direction. A tapered tip portion 122c is formed at the tip of the intermediate member 122.

[0130] A plate-shaped bracket BK is fixed to the front wall 13a of the dashboard 13. A pin BKa erected at the tip of the bracket BK is slidably inserted into an elongated hole 122b of the intermediate member 122. The switch SW and a tip 122c of the intermediate member 122 face each other with a space therebetween.

[0131] In the initial position (when the forward / reverse lever 16 is in the neutral position), the pin BKa of the bracket BK is located at the upper end of the long hole 122b of the intermediate member 122. In addition, the intermediate member 122 is parallel to the vertical direction.

[0132] When the operator depresses the brake pedal 15, the auxiliary member 131 rotates clockwise around the rotation fulcrum 15c together with the brake pedal 15. This excites the switch SW, activating the negative brake. When the brake pedal 15 is released, the brake pedal 15 returns to its original position due to the restoring force.

[0133] On the other hand, for example, when an obstacle G is detected by the distance image sensor 2 while the vehicle is moving backward, the control device 3 outputs a brake signal to drive the second actuator 30A. When the output shaft 30Aa is pushed by driving the second actuator 30A, the intermediate member 122 rises along the pin BKa via the cable 112 and presses the switch SW, thereby exciting the switch SW. This activates the negative brake. The intermediate member 122 is configured not to interfere with other members such as the brake pedal 15 when pressed by the cable 112.

[0134] When the output shaft 30Aa of the second actuator 30A returns to its original position, the intermediate member 122 also returns to its original position via the cable 112.

[0135] According to the brake mechanism 1N of the construction vehicle according to this embodiment, for example, when an obstacle G is detected by the distance image sensor 2 while reversing, the control device 3 outputs a brake signal to activate the second actuator 30A. This allows the negative brake to be activated via the second actuator 30A, the second transmission mechanism Q2, and the switch SW, even if the operator does not step on the brake pedal 15.

[0136] Moreover, according to this embodiment, the brake mechanism 1N for a construction vehicle can be formed with a simple structure.

[0137] [Twelfth embodiment] Next, a brake mechanism 1P for a construction vehicle according to a twelfth embodiment will be described. As shown in Fig. 29 and Fig. 30, the brake mechanism 1P according to the twelfth embodiment is equipped with the brake means 6Bn and the brake means 6A described above. In the twelfth embodiment, the differences from the first embodiment will be mainly described.

[0138] As shown in Fig. 29 and Fig. 30, the brake means 6Bn includes a first actuator 101, a second actuator 30B, a third actuator 201, and an electromagnetic valve (first switching valve) V10. The first actuator 101 can be, for example, any of various cylinders, and in this embodiment, a master cylinder is used. The first actuator 101 is fixed, for example, to the front surface of the front wall 13a of the dashboard 13 via a bracket BK.

[0139] The first actuator 101 includes a main body 102, a shaft portion 103 protruding from the main body 102, and an accessory member 104 attached to the shaft portion 103. The accessory member 104 is a plate-like member that connects the main body plate 15a of the brake pedal 15 and the shaft portion 103. As shown in Fig. 30, the first actuator 101 and the drum brake DB are connected via a first flow path 209 through which pressure oil (brake fluid) flows.

[0140] When the brake pedal 15 is depressed and rotates around the rotation fulcrum 15c, the shaft 103 and the accessory member 104 are pressed, and the first actuator 101 is actuated. This causes pressurized oil (brake fluid) to flow into the drum brake DB, which expands and applies the brakes. The number of drum brakes DB may be set appropriately according to the number of tires 11B.

[0141] As shown in Fig. 30, the second actuator 30B is a device that operates the output shaft 30Ba based on a brake signal from the control device (control unit) 3. The second actuator 30B can be various cylinders such as an air cylinder or an electric cylinder, but in this embodiment, a hydraulic cylinder is used. The second actuator 30B may be installed anywhere on the vehicle body.

[0142] The third actuator 201 can be, for example, any type of cylinder, and in this embodiment, a master cylinder is used. The third actuator 201 is pressurized by the output shaft 30Ba of the second actuator 30B, and is a device that sends pressure oil (brake fluid) to the drum brake DB side. A brake fluid reserve tank RT1 is connected to the third actuator 201.

[0143] The third actuator 201 and a solenoid valve (first changeover valve) V10 provided in the first flow path 209 are connected via a second flow path 211. The solenoid valve (first changeover valve) V10 is a two-position, four-port valve that switches the flow path based on a brake signal from the control device (control unit) 3.

[0144] 30, when the solenoid valve (first switching valve) V10 is in the right position, the first actuator 101 and the drum brake DB communicate with each other, and when the solenoid valve (first switching valve) V10 is in the left position, the third actuator 201 and the drum brake DB communicate with each other.

[0145] As shown in FIG. 29, the switch 210 is electrically connected to the electromagnetic valve (second switching valve) V1 (see FIG. 9) via the control device (control unit) 3. The switch 210 is a switch for operating the above-mentioned braking means 6A. The switch 210 is installed so as to face an auxiliary member 220 provided on the brake pedal 15. The auxiliary member 220 is a plate-like member fixed so as to protrude above the main body plate 15a. When the brake pedal 15 is depressed, the main body plate 15a and the auxiliary member 220 rotate synchronously, and the auxiliary member 220 and the switch 210 come into contact with each other. This switches the flow path of the electromagnetic valve (second switching valve) V1 (see FIG. 9).

[0146] When an operator depresses the brake pedal 15, the shaft 103 is pushed forward via the accessory member 104, the first actuator 101 is actuated, and the drum brake DB expands to actuate the brake. When the brake pedal 15 is released, the brake pedal 15 returns to its original position due to a restoring force.

[0147] Furthermore, when the brake pedal 15 is depressed, the switch 210 is excited by the auxiliary member 220. This causes the control device 3 to output a brake signal to switch the solenoid valve (second switching valve) V1 from the right position to the left position. As a result, even if the engine is running and the forward / reverse lever remains tilted, the swash plate is positioned in the neutral position, no differential pressure is generated between the oil passages T1 and T2, the HST brake acts in the closed circuit U1, and the traveling motor M stops (the above-mentioned brake means 6A is activated).

[0148] On the other hand, for example, when an obstacle G is detected by the distance image sensor 2 while the vehicle is moving backward, the control device 3 outputs a brake signal to drive the second actuator 30B. When the output shaft 30Ba is pushed by the driving of the second actuator 30B, the third actuator 201 is actuated. The control device 3 also outputs a brake signal to switch the solenoid valve (first switching valve) V10 from the right position to the left position. As a result, pressure oil (brake fluid) flows through the third actuator 201, the second flow path 211, and the first flow path 209, and the drum brake DB expands to actuate the brake.

[0149] When the drum brake DB is to be released, the output shaft 30Ba of the second actuator 30B is returned to its original position, and the solenoid valve (first switching valve) V10 is switched from the left position to the right position. This returns the drum brake DB to its original state (a non-operating state of the drum brake DB due to the brake pedal 15).

[0150] According to the brake mechanism 1P of the construction vehicle according to this embodiment, for example, when an obstacle G is detected by the distance image sensor 2 while reversing, the control device 3 outputs a brake signal to activate the second actuator 30B. This allows the drum brake DB to be activated via the third actuator 201 and the electromagnetic valve (first switching valve) V10 even if the operator does not step on the brake pedal 15. This makes it possible to avoid collision accidents caused by human error.

[0151] Moreover, according to this embodiment, the brake mechanism 1P of the construction vehicle can be formed with a simple configuration. The second actuator 30B may be installed anywhere on the vehicle, allowing for high design freedom. Furthermore, according to this embodiment, even if the brake is activated by the second actuator 30B system, the brake pedal 15 and the forward / reverse lever 16 do not move unexpectedly, reducing the risk of injury to the operator's hands and feet.

[0152] Furthermore, according to this embodiment, when the brake pedal 15 is depressed, the drum brake DB system can be braked, and the HST brake can also be operated via the switch 210 (brake means 6A). This allows for more reliable braking.

[0153] Although the embodiment and the modified examples of the present invention have been described above, appropriate design changes are possible within the scope of the present invention. For example, in this embodiment, the "hydraulic mechanism" is configured by the second actuator 30B, the third actuator 201, and the second flow path 211, but the hydraulic mechanism may be configured in other forms. In addition, each embodiment and each modified example can be applied in appropriate combination. [Explanation of symbols]

[0154] 1 Brake mechanism for construction vehicles 2. Distance image sensor (obstacle detection device) 3 Control device (control unit) 4. Detection range 6,6A,6B Braking means 7 Vehicle speed sensor 10. Roller (construction vehicle) 15 Brake pedal 16 Forward / reverse lever 17 Shaft 19 First Cable 22 Base plate 30 Actuator 30B Second actuator 32 Base material 62 Second Cable 65 Third Cable 101 First Actuator G Obstacle M Driving motor 201 Third Actuator V1 Solenoid valve (second switching valve) V10 Solenoid valve (first switching valve)

Claims

1. An obstacle detection device that detects obstacles around the construction vehicle; A brake pedal provided in the driver's seat; A first actuator that is actuated by depression of the brake pedal; a drum brake actuated by the first actuator; a first flow passage connecting the first actuator and the drum brake and through which hydraulic oil flows, A construction vehicle in which the drum brake is actuated by depressing the brake pedal, a hydraulic mechanism provided via a first switching valve provided in the first flow path; a control unit that switches the first switching valve to communicate between the hydraulic mechanism and the drum brake when an obstacle is detected by the obstacle detection device, and operates the drum brake by pressurizing the hydraulic mechanism, An oil passage T1 and an oil passage T2 for operating a swash plate are connected to a traveling pump for traveling the construction vehicle, a second switching valve is provided to switch the flow direction of the hydraulic oil through the oil passage T1 and the oil passage T2; A switch that is actuated by depression of the brake pedal is provided, A brake mechanism for a construction vehicle, characterized in that the second switching valve is switched by the switch, thereby equalizing the pressure between the oil line T1 and the oil line T2 to operate the HST brake.

2. The hydraulic mechanism includes: A second actuator provided on the construction vehicle; a third actuator operated by the second actuator; a second flow passage connecting the third actuator and the first switching valve provided in the first flow passage and through which hydraulic oil flows, 2. A brake mechanism for a construction vehicle as described in claim 1, characterized in that when an obstacle is detected by the obstacle detection device, the first switching valve is switched to connect the second flow path to the drum brake, and the second actuator is activated and the drum brake is activated by pressurizing the third actuator.

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