Vehicle Speed ​​Detection System

Abstract

To appropriately receive a vehicle speed signal according to a vehicle type.SOLUTION: A vehicle speed detection system 50 is one that detects speed of a vehicle, and includes: a vehicle speed signal detection circuit 52 having a receiving unit 60 connected to an output terminal 21 that outputs a vehicle speed signal according to the speed of the vehicle and a switching unit 64 that switches a connection state of the circuit; and a switching control unit 54 that controls the switching of the connection state of the circuit by the switching unit 64 according to the reception status of the vehicle speed signal of the receiving unit 60 while the vehicle is travelling and thereby enables the receiving unit 60 to receive the vehicle speed signal.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a vehicle speed detection system. [Background technology]

[0002] There is known a technology for electronically controlling the rotation of a mixer drum of a mixer truck. For example, Patent Document 1 describes a control system having a mixer drum controller and a display device connected to the controller. Patent Document 1 describes that when the controller receives a vehicle speed signal from a vehicle speed sensor and determines that the vehicle is moving, it starts automatic mixing of the mixer drum.

[0003] In such mixer vehicles, the specifications of the vehicle speed sensor differ depending on the vehicle model, so in the past, a dip switch was provided in the circuit that receives the vehicle speed signal from the vehicle speed sensor, and an operator manually switched the dip switch to configure the circuit according to the vehicle model. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-168954 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the dip switch is manually changed, the worker's man-hours may increase, or the circuit configuration may not be suitable for the vehicle model due to the worker's mistake. If the circuit configuration is not suitable for the vehicle model, the vehicle speed signal cannot be properly received, and it becomes impossible to determine whether the vehicle is moving. Therefore, it is required to be able to properly switch to a circuit configuration suitable for the vehicle model and to properly receive the vehicle speed signal.

[0006] The present invention has been made in view of the above, and has an object to provide a vehicle speed detection system that is capable of appropriately receiving a vehicle speed signal according to the vehicle type. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the objective, the vehicle speed detection system of the present disclosure is a vehicle speed detection system that detects the speed of a vehicle, and includes a vehicle speed signal detection circuit having a receiving unit connected to an output terminal that outputs a vehicle speed signal corresponding to the speed of the vehicle and a switching unit that switches the connection state of the circuit, and a switching control unit that controls the switching of the connection state of the circuit by the switching unit depending on the reception status of the vehicle speed signal of the receiving unit while the vehicle is traveling, thereby putting the receiving unit in a state where it can receive the vehicle speed signal. Effect of the Invention

[0008] According to the present invention, it is possible to appropriately receive a vehicle speed signal according to the vehicle model. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic plan view of a mixer vehicle according to this embodiment. [Diagram 2] FIG. 2 is a schematic rear view of the mixer vehicle according to the present embodiment. [Diagram 3] FIG. 3 is a block diagram showing the hardware configuration of the mixer vehicle according to this embodiment. [Figure 4] FIG. 4 is a graph showing an example of a vehicle speed signal. [Diagram 5] FIG. 5 is a schematic circuit diagram of the vehicle speed detection system. [Figure 6] FIG. 6 is a flowchart illustrating a process flow for switching the connection state of the vehicle speed signal detection circuit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the embodiments described below.

[0011] FIG. 1 is a schematic plan view of a mixer vehicle according to this embodiment, FIG. 2 is a schematic rear view of the mixer vehicle according to this embodiment, and FIG. 3 is a block diagram showing a hardware configuration of the mixer vehicle according to this embodiment.

[0012] (Overall configuration of mixer truck) The overall configuration of a mixer truck 1 according to this embodiment will be described below with reference to Figures 1 to 3. The mixer truck 1 according to this embodiment is a vehicle that transports so-called ready mixed concrete (hereinafter referred to as "ready mixed concrete"), such as mortar or ready mixed concrete, that is charged into a mixer drum 2. In the following description, a case will be described in which the mixer truck 1 loads ready mixed concrete as a cargo.

[0013] As shown in Fig. 1, the mixer drum 2 is a cylindrical container with a bottom that is rotatably mounted on a stand 3, and has an opening 2a at its rear end through which ready-mixed concrete is charged and discharged. The mixer drum 2 is mounted with its rotation axis O tilted so that it gradually becomes higher from the front to the rear of the vehicle. Inside the mixer drum 2, a drum blade (not shown) is arranged in a spiral shape along the inner wall surface of the drum, and the ready-mixed concrete loaded inside the mixer drum 2 is mixed by the drum blade rotating together with the mixer drum 2.

[0014] As shown in Fig. 2, a hopper 16 is provided at the upper rear of the opening 2a of the mixer drum 2. Ready-mixed concrete fed into the mixer truck 1 at a ready-mixed concrete plant is guided to the opening 2a by the hopper 16. A flow guide 17 and a chute 18 are provided at the lower rear of the opening 2a of the mixer drum 2. The ready-mixed concrete discharged from the opening 2a is guided to the chute 18 by the flow guide 17, and is discharged in a predetermined direction by the chute 18.

[0015] The mixer drum 2 is rotationally driven via a drive device 4 shown in Fig. 1 using a traveling engine 10 mounted on the mixer vehicle 1 as a drive source. The drive device 4 is a fluid pressure device that is driven by the rotation of the engine 10 and rotates the mixer drum 2 by the fluid pressure of the working fluid.

[0016] 3, the engine 10 has a throttle valve 10a for adjusting the output and rotation speed of the engine 10. The opening degree of the throttle valve 10a is controlled by the controller 20 via an actuator (not shown) when the engine 10 drives the drive unit 4. The engine 10 is also provided with a rotation sensor 10b that detects the rotation speed of the engine 10 and outputs a signal corresponding to the detected rotation speed to the controller 20.

[0017] The rotation speed of the engine 10 when driving the drive unit 4 is controlled by the controller 20 via the throttle valve 10a so that the rotation speed detected by the rotation sensor 10b becomes a predetermined magnitude. Note that the rotation sensor 10b may detect the rotation speed of a PTO shaft 9 or a drive shaft 8, which are input shafts of the drive unit 4, as described below, or may detect the rotation speed of a hydraulic pump 5, which will be described below.

[0018] The rotation of the engine 10 is transmitted to the drive device 4 via a PTO (Power take-off) shaft 9 that constantly extracts power from the engine 10 and a drive shaft 8 that connects the PTO shaft 9 and the drive device 4.

[0019] The drive device 4 includes a hydraulic pump 5 that is driven by the engine 10 and discharges hydraulic oil OI as a working fluid, and a hydraulic motor 6 that is operated by the hydraulic oil OI supplied from the hydraulic pump 5 and rotates the mixer drum 2. Note that the drive device 4 may use other incompressible fluids as the working fluid instead of the hydraulic oil OI.

[0020] The hydraulic pump 5 is a swash plate type axial piston pump whose discharge volume changes according to the tilt angle of a swash plate (not shown), and has a control valve 5a that controls the flow of hydraulic oil OI from the hydraulic pump 5 to the hydraulic motor 6, a tilt angle adjustment mechanism 5b that adjusts the discharge volume of the hydraulic pump 5 by changing the tilt angle of the swash plate, and a pressure sensor 5c that detects the pressure of the hydraulic oil OI supplied to the hydraulic motor 6.

[0021] The hydraulic pump 5 is rotationally driven by power constantly extracted from the engine 10 via the PTO shaft 9. Note that the drive source for rotating the hydraulic pump 5 is not limited to the engine 10 for traveling, and may be an engine for accessories not used for traveling or an electric motor.

[0022] The control valve 5a is a three-position switching valve having a first position at which the hydraulic oil OI is introduced to the hydraulic motor 6 to rotate the mixer drum 2 in one direction, a second position at which the hydraulic oil OI is introduced to the hydraulic motor 6 to rotate the mixer drum 2 in the other direction, and a cut-off position at which the flow of the hydraulic oil OI from the hydraulic pump 5 to the hydraulic motor 6 is cut off. The positions of the control valve 5a are electrically controlled by a controller 20.

[0023] The tilt angle adjustment mechanism 5b has a hydraulic actuator (not shown) that changes the tilt angle of the swash plate, and a solenoid valve (not shown) that controls the hydraulic pressure guided to the hydraulic actuator. The tilt angle adjustment mechanism 5b changes the tilt angle of the swash plate according to the magnitude of the drive current supplied from the controller 20 to the solenoid valve, and the discharge amount of the hydraulic pump 5 is changed according to the change in the tilt angle of the swash plate.

[0024] The pressure sensor 5c outputs a signal corresponding to the detected pressure of the hydraulic oil OI to the controller 20. Note that the pressure sensor 5c may be provided anywhere as long as it can detect the pressure of the hydraulic oil OI supplied from the hydraulic pump 5 to the hydraulic motor 6, which is the pressure of the hydraulic oil in the drive device 4, and may be provided in the hydraulic motor 6.

[0025] The hydraulic pump 5 is not limited to the above type of pump, and may be any type of pump as long as the discharge capacity can be varied. For example, the hydraulic pump 5 may be a swash plate type axial piston pump in which the discharge volume and discharge direction are changed according to the tilt angle of the swash plate. Alternatively, the hydraulic pump 5 may be a fixed volume pump in which the swash plate is fixed. In this case, the discharge volume may be changed according to the opening degree of a switching valve provided in the pump.

[0026] The hydraulic motor 6 is a swash plate type axial piston motor whose capacity changes according to the tilt angle of a swash plate (not shown), and has a rotation sensor 6a that detects the rotation direction and rotation speed of an output shaft (not shown) of the hydraulic motor 6, and a tilt angle adjustment mechanism 6b that adjusts the tilt angle of the swash plate.

[0027] The rotation sensor 6a outputs a signal corresponding to the detected rotation direction and rotation speed of the output shaft to the controller 20. The rotation speed and rotation direction of the hydraulic motor 6 detected by the rotation sensor 6a correlate with the rotation speed and rotation direction of the mixer drum 2 as described later.

[0028] The tilt angle adjustment mechanism 6b has a hydraulic actuator (not shown) that changes the tilt angle of the swash plate, and a solenoid valve (not shown) that controls the hydraulic pressure guided to the hydraulic actuator. The tilt angle of the swash plate changes according to the current value supplied from the controller 20 to the solenoid valve, and the capacity of the hydraulic motor 6 is changed.

[0029] The hydraulic motor 6 is not limited to the above type of motor, and may be any type of hydraulic motor. For example, the hydraulic motor 6 may be a swash plate type axial piston motor whose capacity can be switched between two levels: a small capacity for high speed rotation and a large capacity for normal rotation.

[0030] In the drive device 4 configured as described above, hydraulic oil discharged from the hydraulic pump 5 is supplied to the hydraulic motor 6, thereby rotating the hydraulic motor 6, and the rotation speed of the hydraulic motor 6 is changed according to the amount of oil supplied and the tilt angle of the swash plate of the hydraulic motor 6. In addition, the rotation direction of the hydraulic motor 6 is switched by switching the position of the control valve 5a of the hydraulic pump 5.

[0031] The output shaft of the drive unit 4, i.e., the output shaft of the hydraulic motor 6, is connected to the rotating shaft O of the mixer drum 2 via a reducer 7. For this reason, it is possible to increase or decrease the rotation speed of the mixer drum 2 by increasing or decreasing the rotation speed of the hydraulic motor 6, and it is possible to switch the rotation direction of the mixer drum 2 between the mixing direction, which is the forward rotation direction, and the discharge direction, which is the reverse rotation direction, by switching the rotation direction of the hydraulic motor 6.

[0032] In this way, since the rotation speed and rotation direction of the mixer drum 2 are correlated with the rotation speed and rotation direction of the hydraulic motor 6, it is possible to grasp the rotation speed and rotation direction of the mixer drum 2 from the detection value of the rotation sensor 6a of the hydraulic motor 6. Note that the rotation sensor 6a may be a sensor that detects the rotation speed and rotation direction of the mixer drum 2 instead of the hydraulic motor 6.

[0033] When the mixer drum 2 is rotated in the mixing direction, the fresh concrete in the mixer drum 2 moves forward while being stirred by the drum blades. On the other hand, when the mixer drum 2 is rotated in the discharge direction, the fresh concrete in the mixer drum 2 moves backward while being stirred by the drum blades.

[0034] In this way, by rotating the mixer drum 2 in the discharge direction, which is the opposite direction to the mixing direction, the ready-mixed concrete can be discharged from the opening 2a of the mixer drum 2. The ready-mixed concrete discharged from the mixer drum 2 is guided to a predetermined position via the flow guide 17 and the chute 18.

[0035] When fresh concrete is poured into the mixer drum 2 through the hopper 16, the mixer drum 2 is rotated in the stirring direction at a higher speed than during stirring, thereby quickly moving the poured fresh concrete to the front of the mixer drum 2.

[0036] (Control System) The mixer vehicle 1 is provided with a control system 100 that controls the mixer drum 2 of the mixer vehicle 1. As shown in Fig. 3, the control system 100 has a controller 20, a display device 30, a first operation panel 41, a second operation panel 42, a third operation panel 43, and a fourth operation panel 44.

[0037] (controller) The controller 20 is a computer that controls the drive device 4 to control the operation of the mixer drum 2. The controller 20 is composed of a microcomputer equipped with, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an I / O interface (Input / Output Interface). The RAM stores data for CPU processing, the ROM stores the CPU's control program and the like in advance, and the I / O interface is used for inputting and outputting information to and from connected devices. The operation of the drive device 4 is controlled by operating the CPU, RAM, and the like in accordance with the program stored in the ROM.

[0038] As described above, the rotation sensor 6a of the hydraulic motor 6, the rotation sensor 10b of the engine 10, and the pressure sensor 5c of the hydraulic pump 5 are connected to the controller 20, and values ​​detected by these sensors are input to the controller 20. As described above, the solenoid valve of the tilt angle adjustment mechanism 5b, the solenoid valve of the tilt angle adjustment mechanism 6b, the control valve 5a, and the throttle valve 10a are connected to the controller 20, and command values ​​for operating these are output from the controller 20. Note that the controller 20 is connected to the rotation sensor 6a, the rotation sensor 10b, the pressure sensor 5c, the solenoid valves, the control valve 5a, and the throttle valve 10a by wires (wiring), and transmits and receives information by wired communication, but is not limited to this, and may be connected wirelessly, or information may be transmitted and received wirelessly.

[0039] (display device) The display device 30 is a display that displays images, for example, the operating state of the mixer drum 2. The display device 30 is preferably disposed in the cab 11 at a position within the cab 11 that is easily visible to an operator. The display device 30 may, for example, have a monitor that displays images, as well as a microcomputer equipped with a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an I / O interface (Input / Output Interface), and the like, similar to the controller 20.

[0040] The display device 30 is connected to the controller 20 and transmits and receives information (signals) to and from the controller 20. In this embodiment, the display device 30 is connected to the controller 20 via a CAN (Controller Area Network), and image data generated by the CPU of the controller 20 is transmitted to the display device 30 via the CAN, and an image is displayed on the monitor of the display device 30. The image data may be generated by the CPU of the display device 30 based on a signal transmitted from the controller 20. The display device 30 is connected to the controller 20 via a wire (wiring) and transmits and receives information via wired communication, but is not limited thereto, and may be connected wirelessly or may transmit and receive information via wireless communication. The display device 30 and the controller 20 may also be connected via a communication network that uses a communication standard other than CAN.

[0041] The display device 30 is connected to an output terminal 21 that outputs a vehicle speed signal corresponding to the speed of the mixer vehicle 1 and a parking brake switch 22 that detects the operation state of the parking brake, and receives detection values ​​detected by these devices. That is, in this embodiment, the controller 20 is not directly connected to the output terminal 21 and the parking brake switch 22, but is connected to the output terminal 21 and the parking brake switch 22 via the display device 30. The output terminal 21 is provided on the engine 10 side and is an interface for connecting to the control system 100 side. The output terminal 21 is connected to a vehicle speed sensor 21A provided on the engine 10. The vehicle speed sensor 21A detects the rotation of the engine 10 as a vehicle speed signal, and the output terminal 21 outputs the vehicle speed signal detected by the vehicle speed sensor 21A to a connection destination. The display device 30 is connected to the output terminal 21 and the parking brake switch 22 by wire (wiring) and transmits and receives information by wired communication, but is not limited thereto, and may be connected wirelessly, or may transmit and receive information by wireless communication.

[0042] In this manner, in this embodiment, devices that acquire data related to the vehicle, such as the output terminal 21 and the parking brake switch 22, are connected to the display device 30, not directly to the controller 20. This makes it possible to reduce the number of connections (here, the number of wires) between the devices that acquire data related to the vehicle and the controller 20, which is preferable. In particular, when connecting the devices that acquire data related to the vehicle and the controller 20 with wires, the length of the wires becomes long, so reducing the number of wires is particularly effective. Note that the transmission and reception of information between the devices that acquire data related to the vehicle and the controller 20 is performed collectively between the display device 30 and the controller 20.

[0043] Furthermore, the display device 30 may have only a display function without having a microcomputer. The installation location of the display device 30 is not limited to inside the cab 11, and may be anywhere that is easy for an operator to see, for example, near where the second operation panel 42 (described later) is located at the rear of the vehicle. Furthermore, a plurality of display devices 30 may be provided in the vehicle.

[0044] (1st operation panel) The first operation panel 41 is an input device that accepts input (operation) by an operator to control the operation of the mixer drum 2. The first operation panel 41 is connected to the controller 20 and transmits and receives information (signals) to and from the controller 20. The first operation panel 41 is directly connected to the controller 20 without going through the display device 30. Note that the first operation panel 41 is connected to the controller 20 by wire (wiring) and transmits and receives information by wired communication, but is not limited thereto, and may be connected wirelessly, or may transmit and receive information by wireless communication.

[0045] In this embodiment, the first operation panel 41 is provided with a potentiometer 41a and an emergency stop switch 41b.

[0046] The potentiometer 41a is a user interface for changing the rotation direction and rotation speed of the mixer drum 2, and receives a rotation control input, which is an input by an operator for controlling the rotation of the mixer drum 2. In this embodiment, the potentiometer 41a is a dial knob type. The first operation panel 41 detects the rotation control input to the potentiometer 41a by the operator, and outputs information indicating the content of the rotation control input to the controller 20. The controller 20 controls the operation of the mixer drum 2 based on the information indicating the content of the rotation control input.

[0047] The emergency stop switch 41b is a user interface for stopping the rotation of the mixer drum 2, and accepts an emergency stop input by an operator for stopping the rotation of the mixer drum 2. The first operation panel 41 detects an emergency stop input to the emergency stop switch 41b by an operator, and outputs information that the emergency stop input has been detected to the controller 20. When the controller 20 acquires the information that the emergency stop input has been detected, it stops the rotation of the mixer drum 2.

[0048] (2nd operation panel) The second operation panel 42 is an input device that accepts input (operation) from an operator to control the operation of the mixer drum 2. The second operation panel 42 is connected to the controller 20 and transmits and receives information (signals) to and from the controller 20. The second operation panel 42 is directly connected to the controller 20 without going through the display device 30. Note that the second operation panel 42 is connected to the controller 20 by wire (wiring) and transmits and receives information by wired communication, but is not limited thereto, and may be connected wirelessly, or may transmit and receive information by wireless communication.

[0049] In this embodiment, the second operation panel 42 is provided with a potentiometer 42a and an emergency stop switch 42b.

[0050] The potentiometer 42a receives a rotation control input from an operator, similar to the potentiometer 41a of the first operation panel 41. The second operation panel 42 detects the rotation control input to the potentiometer 42a by the operator, and outputs information indicating the content of the rotation control input to the controller 20. The controller 20 controls the operation of the mixer drum 2 based on the information indicating the content of the rotation control input.

[0051] The emergency stop switch 42b accepts an emergency stop input by an operator, similar to the emergency stop switch 41b of the first operation panel 41. The second operation panel 42 detects an emergency stop input to the emergency stop switch 42b by an operator, and outputs information that the emergency stop input has been detected to the controller 20. When the controller 20 acquires the information that the emergency stop input has been detected, it stops the rotation of the mixer drum 2.

[0052] In this embodiment, the second operation panel 42 is provided outside the driver's cab 11. More specifically, as shown in FIG. 1, the second operation panel 42 is provided at the right rear of the mixer vehicle 1 so that the mixer drum 2 can be operated while watching the amount of ready-mixed concrete discharged through the chute 18 to the right side of the vehicle. For example, when discharging ready-mixed concrete with two mixer vehicles 1 arranged side by side, it is possible to supply ready-mixed concrete without interruption or to supply a large amount of ready-mixed concrete by operating the second operation panel 42 provided at the right rear of one vehicle while operating the first operation panel 41 provided at the left rear of the other vehicle. However, the installation position of the second operation panel 42 is not limited to the right rear of the vehicle and may be any position. The second operation panel 42 may be a fixed type fixed to the vehicle, or a removable type connected to the vehicle via a cable and removable.

[0053] (3rd operation panel) The third operation panel 43 is an input device that accepts input (operation) by an operator to control the operation of the mixer drum 2. The third operation panel 43 is connected to the display device 30 and transmits and receives information (signals) to and from the display device 30. That is, the third operation panel 43 is not directly connected to the controller 20, but is connected to the controller 20 via the display device 30. The third operation panel 43 is connected to the display device 30 by wire (wiring) and transmits and receives information by wired communication, but is not limited thereto, and may be connected wirelessly or may transmit and receive information by wireless communication. By configuring the operation signal of the third operation panel 43 to be transmitted to the controller 20 via the display device 30 in this way, wiring connecting the third operation panel 43 and the controller 20 is not required. The reduction in the number of wires arranged from the controller 20 improves the degree of freedom in the arrangement of the display device 30 and the third operation panel 43, and makes it possible to arrange the display device 30 and the third operation panel 43 in a position where the operator can easily work. As a result, the ease of operation of the mixer drum 2 by the operator can be improved.

[0054] In this embodiment, the third operation panel 43 is provided with a potentiometer 43a, an emergency stop switch 43b, and an automatic mixing switch 43c.

[0055] The potentiometer 43a receives a rotation control input from an operator, similar to the potentiometer 41a of the first control panel 41. The third control panel 43 detects the rotation control input to the potentiometer 43a by the operator, and outputs information indicating the content of the rotation control input to the display device 30. The display device 30 transmits the information indicating the content of the rotation control input obtained from the third control panel 43 to the controller 20. The controller 20 controls the operation of the mixer drum 2 based on the information indicating the content of the rotation control input obtained from the display device 30.

[0056] The emergency stop switch 43b accepts an emergency stop input by an operator, similar to the emergency stop switch 41b of the first operation panel 41. The third operation panel 43 detects an emergency stop input to the emergency stop switch 43b by an operator, and outputs information to the effect that the emergency stop input has been detected to the display device 30. The display device 30 transmits the information to the effect that the emergency stop input has been detected, acquired from the third operation panel 43, to the controller 20. When the controller 20 acquires the information to the effect that the emergency stop input has been detected from the display device 30, it stops the rotation of the mixer drum 2.

[0057] The automatic mixing switch 43c is a user interface for automatically mixing the mixer drum 2, and receives an automatic mixing input, which is an input by an operator for executing automatic mixing of the mixer drum 2. The procedure for executing automatic mixing will be described later.

[0058] In this embodiment, the third operation panel 43 is provided in the cab 11 so as to enable the operation of the mixer drum 2 even when the vehicle is traveling. However, the installation location of the third operation panel 43 is not limited to inside the cab 11 and may be any location. In addition, the third operation panel 43 may be a stationary type that is fixed to the vehicle, or a detachable type that is connected to the vehicle via a cable and can be detached.

[0059] (4th operation panel) The fourth operation panel 44 is an input device that accepts input (operation) by an operator to control the operation of the mixer drum 2. The fourth operation panel 44 is connected to the controller 20 and transmits and receives information (signals) to and from the controller 20. The fourth operation panel 44 is directly connected to the controller 20 without going through the display device 30. Note that the fourth operation panel 44 is connected to the controller 20 by wire (wiring) and transmits and receives information by wired communication, but is not limited thereto, and may be connected wirelessly, or may transmit and receive information by wireless communication.

[0060] In this embodiment, the fourth operation panel 44 is provided with a potentiometer 44a and an emergency stop switch 44b.

[0061] The potentiometer 44a receives a rotation control input from an operator, similar to the potentiometer 41a of the first control panel 41. The fourth control panel 44 detects the rotation control input to the potentiometer 44a by the operator, and outputs information indicating the content of the rotation control input to the controller 20. The controller 20 controls the operation of the mixer drum 2 based on the information indicating the content of the rotation control input.

[0062] The emergency stop switch 44b accepts an emergency stop input by an operator, similar to the emergency stop switch 41b of the first operation panel 41. The fourth operation panel 44 detects an emergency stop input to the emergency stop switch 44b by an operator, and outputs information that the emergency stop input has been detected to the controller 20. When the controller 20 acquires the information that the emergency stop input has been detected, it stops the rotation of the mixer drum 2.

[0063] In this embodiment, the fourth operation panel 44 is provided outside the driver's cab 11. More specifically, as shown in Fig. 1, the fourth operation panel 44 is provided around the hopper 16, i.e., above the vehicle, so as to enable the operation of the mixer drum 2 while checking the remaining amount of ready mixed concrete in the mixer drum 2. However, the installation position of the fourth operation panel 44 is not limited to above the vehicle, and may be any position. Also, the fourth operation panel 44 may be a stationary type that is fixed to the vehicle, or a detachable type that is connected to the vehicle via a cable and can be detached.

[0064] In this embodiment, four operation panels are provided: a first operation panel 41, a second operation panel 42, a third operation panel 43, and a fourth operation panel 44. However, the number and installation positions of the operation panels are not limited to those described above and are arbitrary.

[0065] The control system 100 is configured as described above. Hereinafter, the control of the mixer drum 2 by the control system 100 will be described.

[0066] When an operator inputs a rotation control input to the potentiometers 41a-44a provided on each of the operation panels 41-44, the controller 20 controls the drive device 4 according to the rotation control input to control the rotation of the mixer drum 2. The potentiometers 41a-44a provided on each of the operation panels 41-44 are variable resistors whose electrical resistance value changes according to the amount of rotation operation, and when the operator rotates the potentiometers 41a-44a and a rotation control input is detected, the controller 20 controls each mechanism constituting the drive device 4, such as the tilt angle of the swash plate of the hydraulic pump 5, the tilt angle of the swash plate of the hydraulic motor 6, and the control valve 5a of the hydraulic pump 5, so that the rotation state of the mixer drum 2 becomes a state according to the electrical resistance value of the potentiometers 41a-44a.

[0067] For example, when the potentiometer 43a on the third control panel 43 is rotated clockwise by the operator, the controller 20 rotates the mixer drum 2 in the mixing direction at a rotation speed corresponding to the electrical resistance value of the potentiometer 43a. Conversely, when the potentiometer 43a is rotated counterclockwise by the operator, the controller 20 rotates the mixer drum 2 in the discharge direction at a rotation speed corresponding to the electrical resistance value of the potentiometer 43a. In this way, the rotation control input is an input by the operator when the operation (rotation direction and rotation speed) of the mixer drum 2 is performed by the operator's operation, and can be said to be an input by the operator when the mixer drum 2 performs an operation other than automatic mixing, which will be described later.

[0068] In this way, the mixer vehicle 1 is provided with multiple control panels 41-44. However, if the potentiometers 41a-44a of the control panels 41-44 are operated simultaneously, the controller 20 cannot determine which operation should be prioritized. Therefore, the operation of the mixer drum 2 may be set to be performed by one control panel that has acquired the operating rights.

[0069] Specifically, for example, when the potentiometer 42a of the second operation panel 42 is once rotated to the maximum position and then returned to the neutral position, the second operation panel 42 is given the operation right, and the mixer drum 2 can be operated from then on by the second operation panel 42. While the potentiometer 42a of the second operation panel 42 to which the operation right has been given is being operated, it is impossible to operate it by another operation panel. When the potentiometer 42a of the second operation panel 42 is once rotated to the maximum position and then returned to the neutral position with the potentiometer 42a of the second operation panel 42 returned to the neutral position, the operation right is transferred to the third operation panel 43.

[0070] Information about the operation panel that the operator has the right to operate and the operating status of the mixer drum 2 may be displayed on the display device 30.

[0071] Furthermore, when the parking brake is not activated and the vehicle speed signal indicates that the mixer vehicle 1 is traveling, the controller 20 executes automatic mixing by rotating the mixer drum 2 in the mixing direction. More specifically, when the operator wishes to execute automatic mixing, the operator operates the automatic mixing switch 43c of the third operation panel 43 in the cab 11 to turn on the automatic mixing switch 43c. When the automatic mixing switch 43c is turned on, the third operation panel 43 detects an automatic mixing input indicating that automatic mixing can be executed, and transmits information to the display device 30 indicating that the automatic mixing input has been acquired. Furthermore, when the operator drives the mixer vehicle 1, the operator turns off the parking brake (a state in which the parking brake is not activated) and drives the mixer vehicle 1. The parking brake switch 22 detects that the parking brake has been turned off, and the display device 30 acquires parking off information indicating that the parking brake is not activated from the parking brake switch 22. In addition, the vehicle speed sensor 21A successively detects the vehicle speed of the mixer vehicle 1, and the display device 30 acquires a vehicle speed signal indicating the vehicle speed of the mixer vehicle 1 via the output terminal 21. The display device 30 transmits to the controller 20 information indicating that an automatic mixing input has been acquired from the automatic mixing switch 43c, parking off information acquired from the parking brake switch 22, and the vehicle speed signal acquired from the output terminal 21. The controller 20 starts automatic mixing when it acquires information indicating that an automatic mixing input has been acquired and the parking off information, and when the acquired vehicle speed signal indicates that the mixer vehicle 1 is traveling.

[0072] When the controller 20 determines that the mixer truck 1 is traveling, it is preferable to prohibit, in principle, operation of the potentiometers on the control panels 41-44 in order to prevent discharge of ready mixed concrete. In other words, when the mixer truck 1 is traveling, the controller 20 does not accept rotation control input to the control panels 41-44, and it is preferable that, even if the potentiometers on the control panels 41-44 are operated, the mixer drum 2 is not rotated in response to the operation.

[0073] (Vehicle speed detection system) Here, as described above, the vehicle speed signal is acquired via the output terminal 21. However, since the specifications of the output terminal 21 and the vehicle speed sensor 21A may differ depending on the vehicle model of the mixer vehicle 1, it is required to appropriately receive the vehicle speed signal according to the vehicle model. In response to this, in this embodiment, a vehicle speed detection system 50 capable of switching the connection of a detection circuit for the vehicle speed signal is provided in order to appropriately receive the vehicle speed signal according to the vehicle model. The vehicle speed detection system 50 will be described below.

[0074] First, the vehicle speed signal will be described. Fig. 4 is a graph showing an example of the vehicle speed signal. As shown in Fig. 4, in the example of this embodiment, the vehicle speed signal is a signal with a pulse-like waveform. The frequency of the vehicle speed signal changes depending on the rotation speed of the engine 10, and the higher the rotation speed, the higher the frequency (i.e., the shorter the period T).

[0075] Fig. 5 is a schematic circuit diagram of a vehicle speed detection system. As shown in Fig. 5, the vehicle speed detection system 50 has a vehicle speed signal detection circuit 52 and a switching control unit 54. In this embodiment, the vehicle speed detection system 50 is provided in the display device 30. However, the vehicle speed detection system 50 is not limited to being provided in the display device 30, and may be hardware separate from the display device 30.

[0076] The vehicle speed signal detection circuit 52 is a circuit connected to the output terminal 21. The vehicle speed signal detection circuit 52 includes a receiving unit 60, a power source 62, and a switching unit 64.

[0077] The receiving unit 60 is a circuit (detection circuit) connected to the output terminal 21, and is capable of receiving the vehicle speed signal output from the output terminal 21. The receiving unit 60 is connected to the output terminal 21 by a wiring L1. In this embodiment, the receiving unit 60 is provided in the display device 30, but may be a circuit provided separately from the display device 30.

[0078] The switching unit 64 is a switch unit that switches the connection of the vehicle speed signal detection circuit 52, and is a multiplexer in this embodiment. The switching unit 64 has a first switching unit 64A and a second switching unit 64B. The switching unit 64 is provided in the display device 30, but may be a multiplexer circuit provided separately from the display device 30.

[0079] The first switching unit 64A has a first contact 64AS1 connected to the receiving unit 60 by a wiring L2. A resistor R2 is provided on the wiring L2. The first switching unit 64A has a second contact 64AS2 connected to earth by a wiring L3, and a third contact 64AS3 connected to a power source 62 by a wiring L4. The power source 62 is a supply source that supplies power, such as a battery. The power source 62 is a power source for the display device 30 that also supplies power to the display device 30, but is not limited to being a power source for the display device 30.

[0080] The first switching unit 64A has a switch unit 64A1 and an input unit 64A2. The switch unit 64A1 is a switch capable of switching between a first state in which the first contact 64AS1 and the second contact 64AS2 are connected and the first contact 64AS1 and the third contact 64AS3 are disconnected, and a second state in which the first contact 64AS1 and the third contact 64AS3 are connected and the first contact 64AS1 and the second contact 64AS2 are disconnected. The input unit 64A2 is a mechanism that operates the switch unit 64A1 under the control of the switching control unit 54 to switch the switch unit 64A1 between the first state and the second state. The first state is a state in which the receiving unit 60 (output terminal 21) and the power source 62 are disconnected, and the second state is a state in which the output terminal 21 and the power source 62 are connected via the receiving unit 60. In this embodiment, the circuit configuration connects the output terminal 21 and the power supply 62 via the receiving unit 60 in the second state, but the circuit configuration is not limited to the above description and may be any circuit configuration that connects the output terminal 21 and the power supply 62 in the first state and disconnects the output terminal 21 and the power supply 62 in the second state.

[0081] The second switching unit 64B has a first contact 64BS1 connected to a point P between the output terminal 21 and the receiving unit 60 on the wiring L1 via a wiring L5. The second switching unit 64B has a second contact 64BS2 connected to earth via a wiring L6, and a third contact 64BS3 not connected (floating) to the wiring or the circuit. A resistor R3 is provided on the wiring L6. It can be said that the resistor R3 is provided in parallel with the output terminal 21 and the receiving unit 60.

[0082] The second switching unit 64B has a switch unit 64B1 and an input unit 64B2. The switch unit 64B1 is a switch capable of switching between a third state in which the first contact 64BS1 and the second contact 64BS2 are connected and the first contact 64BS1 and the third contact 64BS3 are not connected, and a fourth state in which the first contact 64BS1 and the third contact 64BS3 are connected and the first contact 64BS1 and the second contact 64BS2 are not connected. The input unit 64B2 is a mechanism that operates the switch unit 64B1 under the control of the switching control unit 54 to switch the switch unit 64B1 between the third state and the fourth state. The third state is a state in which the point P is connected to the resistor R3, and the fourth state is a state in which the point P is not connected to the resistor R3.

[0083] The switching control unit 54 is a computer (microcomputer) equipped with a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an I / O interface (Input / Output Interface), etc. The switching control unit 54 is a computer provided in the display device 30, but may be a computer separate from the display device 30.

[0084] The switching control unit 54 controls the switching of the connection state of the vehicle speed signal detection circuit 52 by the switching unit 64, thereby making the receiving unit 60 capable of receiving the vehicle speed signal. The switching control unit 54 operates the switch unit 64A1 via the input unit 64A2 of the first switching unit 64A to switch between the first state and the second state. The switching control unit 54 also operates the switch unit 64B1 via the input unit 64B2 of the second switching unit 64B to switch between the third state and the fourth state.

[0085] (Switching process) The process of switching the connection state of the vehicle speed signal detection circuit 52 by the switching control unit 54 will be described below.

[0086] When performing the switching process, the control system 100 including the vehicle speed detection system 50 is attached to the mixer vehicle 1. That is, the wiring L1 of the vehicle speed signal detection circuit 52 is connected to the output terminal 21 of the mixer vehicle 1, and the receiving unit 60 and the output terminal 21 are connected via the wiring L1. When performing the switching process, as shown in FIG. 5, the vehicle speed signal detection circuit 52 is in a first state in which the receiving unit 60 is grounded and not connected to the power supply 62, and in a third state in which the point P is connected to the resistor R3. Note that the point P may be in a fourth state in which it is not connected to the resistor R3. Then, the mixer vehicle 1 is test-driven in a state in which the vehicle speed signal detection circuit 52 is connected to the output terminal 21 as shown in FIG. 5. The switching control unit 54 detects the reception state of the vehicle speed signal of the receiving unit 60 when the mixer vehicle 1 is test-driven, and switches the connection state of the vehicle speed signal detection circuit 52 according to the reception state of the vehicle speed signal. The process of test driving the mixer vehicle 1 and switching the connection state of the vehicle speed signal detection circuit 52 is performed, for example, as a calibration step before the mixer vehicle 1 is shipped.

[0087] Here, there are two types of mixer vehicles 1: one that cannot output a vehicle speed signal from the output terminal 21 unless a current is supplied to the output terminal 21, and one that can output a vehicle speed signal from the output terminal 21 even if a current is not supplied to the output terminal 21. It can also be said that the output terminal 21 of a vehicle model that cannot output a vehicle speed signal from the output terminal 21 unless a current is supplied is an open collector type, and that the output terminal 21 of a vehicle model that can output a vehicle speed signal from the output terminal 21 even if a current is not supplied is an emitter follower type. In the case of an open collector type, even if the mixer vehicle 1 is test driven in the first state, the output terminal 21 is not connected to the power source 62, so that the vehicle speed signal is not output from the output terminal 21 to the receiving unit 60. Therefore, when the mixer vehicle 1 is test driven, if the receiving unit 60 does not receive a vehicle speed signal, it can be determined that the output terminal 21 is an open collector type, and if the receiving unit 60 receives a vehicle speed signal, it can be determined that the output terminal 21 is an emitter follower type. In this embodiment, this principle is utilized, and the switching control unit 54 judges whether to switch to the first state or the second state based on whether or not the receiving unit 60 receives a vehicle speed signal while the mixer vehicle 1 is being test driven. A specific description will be given below.

[0088] When the receiver 60 does not receive a vehicle speed signal during test driving of the mixer vehicle 1, the switching control unit 54 switches the first switching unit 64A to the second state and switches the second switching unit 64B to the fourth state. As a result, the power source 62 is connected to the output terminal 21 via the receiver 60, so that the output terminal 21 can output a vehicle speed signal to the receiver 60. That is, when the receiver 60 does not detect a vehicle speed signal during test driving of the mixer vehicle 1, the switching control unit 54 determines that the vehicle is an open collector type and connects the power source 62 and the output terminal 21. As a result, in a vehicle model with an open collector type, the receiver 60 is in a state in which it can properly receive a vehicle speed signal. Here, the second switching unit 64B is in the fourth state, but the state of the second switching unit 64B is not limited to the fourth state and may be any state. In addition, the switching of the first switching unit 64A and the second switching unit 64B here may be performed during the test driving or after the test driving.

[0089] On the other hand, when the receiver 60 receives a vehicle speed signal while the mixer vehicle 1 is being test driven, the switching control unit 54 keeps the first switching unit 64A in the first state. That is, when the receiver 60 detects a vehicle speed signal while the mixer vehicle 1 is being test driven, the switching control unit 54 determines that the vehicle is of emitter follower specification and disconnects the power supply 62 from the output terminal 21. This allows the receiver 60 to properly receive the vehicle speed signal in an emitter follower specification vehicle.

[0090] Furthermore, in the mixer vehicle 1 in which the output terminal 21 is of emitter follower specification, there may be a vehicle type in which an intermediate resistor needs to be connected between the output terminal 21 and the receiving unit 60 in order to appropriately output a vehicle speed signal from the output terminal 21, and a vehicle type in which an intermediate resistor does not need to be connected. The specifications of the vehicle speed sensor 21A are different between a vehicle type in which an intermediate resistor is required and a vehicle type in which an intermediate resistor is not required. Furthermore, the number of pulses generated by the vehicle speed sensor 21A per one engine revolution of a vehicle type in which an intermediate resistor is required is greater than the number of pulses generated by the vehicle speed sensor 21A per one engine revolution of a vehicle type in which an intermediate resistor is not required. In this embodiment, taking advantage of this point, the switching control unit 54 judges whether to set the second switching unit 64B to the third state or the fourth state based on the frequency of the vehicle speed signal received by the receiving unit 60 during the test drive of the mixer vehicle 1. A specific description will be given below.

[0091] Specifically, the switching control unit 54 calculates an estimate of the speed of the mixer vehicle 1 after a predetermined time has elapsed since the start of the test run based on the frequency of the vehicle speed signal received by the receiving unit 60 after a predetermined time has elapsed since the mixer vehicle 1 started the test run (in this example, faster than 0 km / h and less than 10 km / h). The predetermined time may be set arbitrarily, for example, one second. The switching control unit 54 is not limited to using the frequency of the vehicle speed signal received by the receiving unit 60 after a predetermined time has elapsed since the mixer vehicle 1 started the test run, but may use the frequency of the vehicle speed signal at a predetermined speed after the mixer vehicle 1 started the test run. In this case, when the predetermined speed is reached, the frequency of the vehicle speed signal at the predetermined speed may be obtained by a switch or the like. The speed of the mixer vehicle 1 can be calculated from the number of pulses per revolution of the engine 10 and the frequency, for example, using the following formula (1).

[0092] V = 3600 H / (n N) (1)

[0093] In equation (1), V is the speed (km / h), 3600 is 60 seconds x 60 (km / h), H is the frequency (Hz), n is the number of pulses of the vehicle speed sensor 21A per rotation of the engine drive shaft, and N is the vehicle speed sensor drive rotation speed (rpm) when the vehicle speed is 60 km / h.

[0094] Here, since the number of pulses per engine revolution differs for each vehicle model as described above, a predetermined number of pulses to be used in the calculation of the estimated value of the speed of the mixer vehicle 1 is set in advance. The switching control unit 54 calculates an estimated value of the speed of the mixer vehicle 1 after a predetermined time has elapsed since the start of the test drive based on the frequency of the vehicle speed signal received by the receiving unit 60 after a predetermined time has elapsed since the mixer vehicle 1 started the test drive and the predetermined number of pulses. Then, based on the calculated estimated value of the speed of the mixer vehicle 1, the switching control unit 54 determines whether to set the third state or the fourth state.

[0095] Specifically, when the estimated value of the speed of the mixer vehicle 1 is lower than a predetermined threshold value, the switching control unit 54 determines that the vehicle is a vehicle that requires an intermediate resistor (i.e., a vehicle with a large number of pulses per engine revolution), and sets the second switching unit 64B to the third state. As a result, the point P between the output terminal 21 of the wiring L1 and the receiving unit 60 is connected to the resistor R3, which is an intermediate resistor. Therefore, even in a vehicle that requires an intermediate resistor, the receiving unit 60 is able to properly receive the vehicle speed signal. Note that, when the estimated value of the speed is calculated by fixing the predetermined number of pulses, the estimated value of the speed tends to be calculated higher for a vehicle that does not require an intermediate resistor (a vehicle with a small number of pulses per engine revolution) than for a vehicle that requires an intermediate resistor (a vehicle with a large number of pulses per engine revolution). Therefore, by determining that the estimated value of the speed of the mixer vehicle 1 is lower than a predetermined threshold value, it is possible to properly determine that the vehicle is a vehicle that requires an intermediate resistor. Note that the threshold value may be set to any speed that a vehicle that does not require an intermediate resistor will reliably exceed when traveling, and may be set to any value, such as 10 km / h.

[0096] On the other hand, when the estimated speed of the mixer vehicle 1 is equal to or greater than a predetermined threshold, the switching control unit 54 determines that the vehicle is one that requires an intermediate resistor (i.e., one vehicle with a small number of pulses per engine revolution), and sets the second switching unit 64B to the fourth state. That is, for example, when the speed one second after the start of the test drive is higher than a generally expected speed, such as several tens of km / h, it is determined that the vehicle is one that does not require an intermediate resistor because the speed was calculated with a fixed number of pulses, and the estimated speed was calculated as a value higher than the actual value. As a result, the point P between the output terminal 21 of the wiring L1 and the receiving unit 60 is not connected to the resistor R3, which is an intermediate resistor. Therefore, even in a vehicle that does not require an intermediate resistor, the receiving unit 60 is able to properly receive the vehicle speed signal.

[0097] The criteria for determining whether to set the vehicle to the third state or the fourth state are not limited to the estimated value of the speed as described above. For example, the frequency of the vehicle speed signal, the number of pulses in a predetermined time, or the like may be used to determine whether to set the vehicle to the third state or the fourth state. In this case, for example, when the frequency or the number of pulses in a predetermined time is equal to or greater than a threshold, the switching control unit 54 may determine that the vehicle is one that requires an intermediate resistor and set the second switching unit 64B to the third state, and when the frequency or the number of pulses in a predetermined time is less than the threshold, the switching control unit 54 may determine that the vehicle is one that does not require an intermediate resistor and set the second switching unit 64B to the fourth state.

[0098] Next, the flow of the process of switching the connection state of the vehicle speed signal detection circuit 52 described above will be described. FIG. 6 is a flow chart for explaining the process of switching the connection state of the vehicle speed signal detection circuit. When performing the process of switching the connection state, the mixer vehicle 1 is test driven with the vehicle speed signal detection circuit 52 connected to the output terminal 21 and the first switching unit 64A in the first state (the power supply 62 is not connected). Then, the switching control unit 54 judges whether the receiving unit 60 detects the vehicle speed signal during the test drive (step S10). If the receiving unit 60 does not detect the vehicle speed signal (step S10; No), the switching control unit 54 determines that the circuit is of open collector type, and sets the first switching unit 64A to the second state (the power supply 62 is connected) and the second switching unit 64B to the fourth state (the resistor R3 is not connected) (step S12). On the other hand, when the receiver 60 detects the vehicle speed signal (step S10; Yes), the switching control unit 54 calculates an estimated value of the vehicle speed from the frequency of the vehicle speed signal after a predetermined time has elapsed since the start of the test drive and the predetermined number of pulses (step S14). The switching control unit 54 determines whether the estimated value of the vehicle speed is equal to or higher than the threshold (step S16). If the estimated value of the vehicle speed is lower than the threshold (step S16; No), the switching control unit 54 determines that the vehicle is a type that requires an intermediate resistor and sets the first switching unit 64A to the first state (a state in which the power supply 62 is not connected) and the second switching unit 64B to the third state (a state in which the resistor R3 is connected) (step S18). On the other hand, if the estimated value of the vehicle speed is equal to or higher than the threshold (step S16; Yes), the switching control unit 54 determines that the vehicle is a type that does not require an intermediate resistor and sets the first switching unit 64A to the first state (a state in which the power supply 62 is not connected) and the second switching unit 64B to the fourth state (a state in which the resistor R3 is not connected) (step S20). This process ends with steps S12, S18, and S20 being executed. Since the connection state of the vehicle speed signal detection circuit 52 does not need to be changed once it is determined, this process may be executed only once, such as before shipping. In step S16, the determination is made based on whether the estimated vehicle speed is equal to or greater than the threshold value, but this is not limited thereto. For example, if the estimated vehicle speed is higher than the threshold value in step S16, step S20 may be executed, and if the estimated vehicle speed is equal to or less than the threshold value in step S16, step S18 may be executed.

[0099] (effect) As described above, the vehicle speed detection system 50 according to this embodiment detects the speed of the mixer vehicle 1 and includes a vehicle speed signal detection circuit 52 and a switching control unit 54. The vehicle speed signal detection circuit 52 includes a receiving unit 60 connected to the output terminal 21 that outputs a vehicle speed signal corresponding to the speed of the mixer vehicle 1, and a switching unit 64 that switches the connection state of the vehicle speed signal detection circuit 52. The switching control unit 54 controls the switching of the connection state of the mixer vehicle 1 by the switching unit 64 according to the reception state of the vehicle speed signal of the receiving unit 60 while the mixer vehicle 1 is traveling, thereby making the receiving unit 60 capable of receiving the vehicle speed signal.

[0100] Here, since the specifications of the output terminal 21 and the vehicle speed sensor 21A may differ depending on the vehicle model of the mixer vehicle 1, it is required to appropriately receive the vehicle speed signal according to the vehicle model. In response to this, the vehicle speed detection system 50 according to the present embodiment is provided with a vehicle speed signal detection circuit 52 connected to the output terminal 21, and switches the connection of the vehicle speed signal detection circuit 52 according to the reception state of the vehicle speed signal of the receiving unit 60 when the mixer vehicle 1 is actually test driven. Therefore, according to this embodiment, it is possible to set the vehicle speed signal detection circuit 52 to a connection state according to the vehicle model, and it is possible to appropriately receive the vehicle speed signal according to the vehicle model. In addition, according to the vehicle speed detection system 50, the circuit configuration is automatically set to one that can appropriately receive the vehicle speed signal according to the vehicle model, so that the burden on the operator is reduced, and it is also possible to prevent the circuit configuration from being erroneously set due to an operator's mistake.

[0101] The vehicle speed signal detected by the vehicle speed detection system 50 is used to determine whether the mixer vehicle 1 is stopped or moving when automatic mixing or the like is started as described above. The vehicle speed signal may also be used to calculate the recommended time for maintenance, for example. In this case, for example, the controller 20 or the display device 30 calculates an integrated value of the travel distance of the mixer vehicle 1 from the vehicle speed and travel time calculated based on the vehicle speed signal. Then, when the integrated value of the travel distance exceeds a predetermined time, it is determined that the recommended time for maintenance has arrived, and for example, the display device 30 may display a notification on the monitor that maintenance is recommended.

[0102] The switching unit 64 can switch between a first state in which the output terminal 21 and the power supply 62 are disconnected, and a second state in which the output terminal 21 and the power supply 62 are connected. If the receiver 60 does not receive a vehicle speed signal when the mixer vehicle 1 is test-driving in the first state, the switching control unit 54 sets the switching unit 64 to the second state, and if the receiver 60 receives a vehicle speed signal when the mixer vehicle 1 is test-driving, the switching control unit 54 sets the switching unit 64 to the first state. According to this embodiment, it is possible to properly receive the vehicle speed signal in both the open collector specification and the emitter follower specification.

[0103] The switching unit 64 can also switch between a third state in which the resistor R3 provided in parallel between the output terminal 21 and the receiving unit 60 is connected, and a fourth state in which the resistor R3 is not connected. The switching control unit 54 determines whether to put the switching unit 64 in the third state or the fourth state based on the frequency of the vehicle speed signal received by the receiving unit 60 when the mixer vehicle 1 is traveling in the first state. According to this embodiment, it is possible to properly receive the vehicle speed signal in both vehicle types that do not require an intermediate resistor and vehicle types that do require an intermediate resistor.

[0104] In addition, the switching control unit 54 calculates an estimate of the speed of the mixer vehicle 1 based on the frequency of the vehicle speed signal when the mixer vehicle 1 starts traveling and a preset predetermined number of pulses, and if the estimate is lower than a threshold value, the switching unit 64 is set to the third state, and if the estimate is equal to or higher than the threshold value, the switching unit 64 is set to the fourth state. According to this embodiment, it is possible to properly receive the vehicle speed signal in both vehicle types that do not require an intermediate resistor and vehicle types that do require an intermediate resistor.

[0105] Incidentally, the vehicle speed detection system 50 according to this embodiment is mounted on the mixer vehicle 1 to detect the vehicle speed of the mixer vehicle 1, but may be configured to detect the vehicle speed of any vehicle, not limited to the mixer vehicle 1.

[0106] Although the embodiments and examples of the present invention have been described above, the embodiments are not limited to the contents of these embodiments. The above-mentioned components include those that a person skilled in the art can easily imagine, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the above-mentioned components can be appropriately combined. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the gist of the above-mentioned embodiments. [Explanation of symbols]

[0107] 1 Mixer Truck 20 Controller 21 Output terminal 21A Vehicle speed sensor 22 Parking brake switch 30 Display device 50 Vehicle speed detection system 52 Vehicle speed signal detection circuit 54 Switching control section 60 Receiving unit 62 Power supply 64 Switching section

Claims

1. A vehicle speed detection system for detecting a speed of a vehicle, a vehicle speed signal detection circuit including a receiving unit connected to an output terminal for outputting a vehicle speed signal corresponding to the vehicle speed, and a switching unit for switching a connection state of the circuit; a switching control unit that controls switching of a connection state of a circuit by the switching unit in accordance with a reception state of the vehicle speed signal by the receiving unit while the vehicle is traveling, thereby making the receiving unit capable of receiving the vehicle speed signal; having the switching unit is capable of switching between a first state in which the output terminal and the power supply are in a disconnected state and a second state in which the output terminal and the power supply are in a connected state, The switching control unit sets the switching unit to the second state when the receiving unit does not receive the vehicle speed signal while the vehicle is traveling in the first state, and sets the switching unit to the first state when the receiving unit receives the vehicle speed signal while the vehicle is traveling. Vehicle speed detection system.

2. the switching unit is capable of switching between a third state in which a resistor provided in parallel to the output terminal and the receiving unit is connected and a fourth state in which the resistor is disconnected; 2. The vehicle speed detection system according to claim 1, wherein the switching control unit determines whether to set the switching unit to the third state or the fourth state based on a frequency of the vehicle speed signal received by the receiving unit when the vehicle is traveling in the first state.

3. 3. The vehicle speed detection system of claim 2, wherein the switching control unit calculates an estimate of the vehicle's speed based on a frequency of the vehicle speed signal when the vehicle starts traveling and a predetermined number of pulses that is set in advance, and when the estimate is lower than a threshold value, the switching unit is set to the third state, and when the estimate is equal to or greater than the threshold value, the switching unit is set to the fourth state.

Images