Mixer drum control device

Abstract

To accurately control a mixer drum.SOLUTION: A controller 20 controls a drive unit 4 that rotatably drives a mixer drum 2, where the drive unit 4 includes an electromagnetic proportional valve 31 that controls a flow of a working fluid guided from a hydraulic pump 5 to a hydraulic motor 6, and the electromagnetic proportional valve 31 includes a solenoid 32 that changes over a normal rotation position 31A that guides to the hydraulic motor 6 the working fluid discharged by the hydraulic pump 5 so that the mixer drum 2 rotates in a normal rotation direction and a reverse rotation position 31B that guides to the hydraulic motor 6 the working fluid discharged by the hydraulic pump 5 so that the mixer drum 2 rotates in a reverse rotation direction. The controller 20 determines the rotation direction of the mixer drum 2 from a command value to the solenoid 32 when the mixer drum 2 rotates in the normal rotation direction and from a command value to the solenoid 32 when the mixer drum 2 rotates in the reverse rotation direction.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a mixer drum control device. [Background technology]

[0002] Patent Document 1 discloses a mixer truck that is mounted on a stand and includes a mixer drum that is rotatable in a mixing direction and a discharge direction, a drive device for driving the mixer drum to rotate, and a controller for controlling the operation of the drive device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-228152 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a mixer truck such as that described in Patent Document 1, it is possible to use a sensor that detects the rotation direction of the mixer drum in order to control the mixer drum. However, in this case, if an abnormality occurs in the sensor, the rotation direction of the mixer drum cannot be accurately detected, and there is a risk that the mixer drum cannot be accurately controlled.

[0005] The present invention has been made in consideration of the above problems, and has an object to accurately control a mixer drum. [Means for solving the problem]

[0006] The present invention is a mixer drum control device that controls a drive device that drives a mixer drum to rotate, the drive device having a fluid pressure pump driven by a drive source to discharge a working fluid, a fluid pressure motor that is operated by the working fluid discharged from the fluid pressure pump to drive the mixer drum to rotate, and a solenoid valve that controls the flow of the working fluid guided from the fluid pressure pump to the fluid pressure motor, the solenoid having a solenoid for switching between a forward rotation position in which the working fluid discharged by the fluid pressure pump is guided to the fluid pressure motor so that the mixer drum rotates in the forward rotation direction, and a reverse position in which the working fluid discharged by the fluid pressure pump is guided to the fluid pressure motor so that the mixer drum rotates in the reverse direction, and the mixer drum control device is characterized in that it determines the rotation direction of the mixer drum based on a command value to the solenoid when rotating the mixer drum in the forward rotation direction and a command value to the solenoid when rotating the mixer drum in the reverse direction.

[0007] In this invention, the mixer drum control device determines the rotation direction of the mixer drum based on a command value to a solenoid for switching between a forward rotation position and a reverse rotation position. In other words, the mixer drum control device determines the rotation direction of the mixer drum based on a command value to a solenoid valve that controls the flow of working fluid guided from the fluid pressure pump to the fluid pressure motor, rather than on the detection result of a sensor or the like. Therefore, the rotation direction of the mixer drum can be accurately determined.

[0008] The mixer drum control device of the present invention is characterized in that, to determine the rotation direction of the mixer drum, if a rotation sensor that detects rotation information of the mixer drum or the fluid pressure motor is normal, the detection result of the rotation sensor is used, and if the rotation sensor is abnormal, a command value to a solenoid is used.

[0009] According to the present invention, even if an abnormality occurs in the rotation sensor, the rotation direction of the mixer drum can be determined based on the command value to the solenoid. Effect of the Invention

[0010] The present invention provides precise control of the mixer drum. [Brief description of the drawings]

[0011] [Figure 1A] FIG. 2 is a plan view of the mixer truck according to the embodiment of the present invention as viewed from above. [Figure 1B] FIG. 2 is a rear view of the mixer truck according to the embodiment of the present invention as viewed from the rear. [Diagram 2] 1 is a block diagram showing a hardware configuration of a mixer vehicle according to an embodiment of the present invention. [Diagram 3] 11 is a flowchart showing a process in which the controller determines whether the rotation sensor is normal and calculates (determines) the rotation speed and rotation direction of the mixer drum. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A mixer truck according to an embodiment of the present invention will now be described with reference to the drawings.

[0013] The mixer truck 1 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 load.

[0014] 1A and 1B, the mixer vehicle 1 is a vehicle equipped with a cab 11 and a stand 3. The mixer vehicle 1 is equipped with a mixer drum 2 rotatably mounted on the vehicle, a drive unit 4 that drives the mixer drum 2 to rotate, and a controller 20 as a mixer drum control device that controls the drive unit 4.

[0015] 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. Within 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 in the mixer drum 2 is mixed by the drum blade rotating together with the mixer drum 2.

[0016] 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.

[0017] The mixer drum 2 is rotationally driven via a drive unit 4 using a traveling engine 10 mounted on the mixer vehicle 1 as a drive source. The drive unit 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 a working fluid. In the drive unit 4, hydraulic oil is used as the working fluid, but other non-compressible fluids may also be used as the working fluid. The rotation of the engine 10 is transmitted to the drive unit 4 via a PTO shaft 9 (PTO: Power take-off) that constantly extracts power from the engine 10 and a drive shaft 8 that connects the PTO shaft 9 and the drive unit 4.

[0018] 2, 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 a controller 20.

[0019] The drive unit 4 has a hydraulic pump 5 as a fluid pressure pump driven by an engine 10 as a drive source and discharging hydraulic oil as a working fluid, a hydraulic motor 6 as a fluid pressure motor operated by the hydraulic oil discharged from the hydraulic pump 5 to rotate the mixer drum 2, and an electromagnetic proportional valve 31 as a solenoid valve controlling the flow of the hydraulic oil guided from the hydraulic pump 5 to the hydraulic motor 6. The drive unit 4 rotates the mixer drum 2 in a forward direction and a reverse direction, and is capable of changing the rotation speed. In this embodiment, the "forward direction" is the stirring direction in which the ready-mixed concrete is stirred and the charging direction in which the ready-mixed concrete is charged, and the "reverse direction" is the discharge direction in which the ready-mixed concrete is discharged.

[0020] The hydraulic pump 5 is rotationally driven by power constantly extracted from the engine 10 via the PTO shaft 9. The drive source for rotationally driving 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. The hydraulic pump 5 is a swash plate type axial piston pump with a variable capacity. The hydraulic pump 5 may be any type of pump as long as the discharge capacity is variable. The hydraulic oil discharged from the hydraulic pump 5 is supplied to the hydraulic motor 6.

[0021] The hydraulic motor 6 is a swash plate type axial piston motor with a variable capacity, and is rotationally driven by the supply of hydraulic oil discharged from the hydraulic pump 5. The rotation of the hydraulic motor 6 is transmitted to the mixer drum 2 via a reduction gear 7. A rotation sensor 6b that detects rotation information of the hydraulic motor 6 is provided on the output shaft 6a of the hydraulic motor 6. In this embodiment, the rotation sensor 6b is a two-phase output type sensor that outputs two-phase pulses of phase A and phase B. The rotation sensor 6b is connected to the controller 20, and outputs the detected two-phase pulse signal to the controller 20 as a detection result.

[0022] A closed circuit L is provided between the hydraulic pump 5 and the hydraulic motor 6, and hydraulic oil circulates through this closed circuit L. An electromagnetic proportional valve 31 is provided in this closed circuit L. The electromagnetic proportional valve 31 has a forward rotation position 31A where the hydraulic oil discharged by the hydraulic pump 5 is guided to the hydraulic motor 6 so that the mixer drum 2 rotates in the forward rotation direction, a reverse position 31B where the hydraulic oil discharged by the hydraulic pump 5 is guided to the hydraulic motor 6 so that the mixer drum 2 rotates in the reverse direction, and a neutral position 31C where the flow of hydraulic oil from the hydraulic pump 5 to the hydraulic motor 6 is blocked.

[0023] The electromagnetic proportional valve 31 has a solenoid 32 that is electronically controlled by the controller 20 and switches between a forward rotation position 31A and a reverse rotation position 31B, and a pair of return springs 33a, 33b. A pair of solenoids 32 is provided, and the first solenoid 32a switches the electromagnetic proportional valve 31 to the forward rotation position 31A, and the second solenoid 32b switches the electromagnetic proportional valve 31 to the reverse rotation position 31B. When the first solenoid 32a is excited, the electromagnetic proportional valve 31 switches to the forward rotation position 31A, and supplies hydraulic oil to the hydraulic motor 6 so as to rotate the mixer drum 2 in the forward rotation direction. When the second solenoid 32b is excited, the electromagnetic proportional valve 31 switches to the reverse rotation position 31B, and supplies hydraulic oil to the hydraulic motor 6 so as to rotate the mixer drum 2 in the reverse direction. The first solenoid 32a and the second solenoid 32b are operated by a command value output from the controller 20. The command value is specifically a current value. By adjusting the current values ​​output to the first solenoid 32a and the second solenoid 32b, the solenoid proportional valve 31 is switched to a forward rotation position 31A, a neutral position 31C, and a reverse rotation position 31B.

[0024] When the first solenoid 32a is energized, the electromagnetic proportional valve 31 is switched to a forward rotation position 31A with an opening degree corresponding to the amount of energization. As a result, hydraulic oil is supplied to the hydraulic motor 6 at a flow rate corresponding to the opening degree of the electromagnetic proportional valve 31 so as to rotate the mixer drum 2 in the forward rotation direction. Conversely, when the second solenoid 32b is energized, the electromagnetic proportional valve 31 is switched to a reverse rotation position 31B with an opening degree corresponding to the amount of energization. As a result, hydraulic oil is supplied to the hydraulic motor 6 at a flow rate corresponding to the opening degree of the electromagnetic proportional valve 31 so as to rotate the mixer drum 2 in the reverse direction. The greater the amount of energization to the first solenoid 32a and the second solenoid 32b, the greater the opening degree of the electromagnetic proportional valve 31, and a larger flow rate is guided to the hydraulic motor 6. When the first solenoid 32a and the second solenoid 32b are de-energized, the solenoid proportional valve 31 is switched to a neutral position 31C by the biasing force of a pair of return springs 33a, 33b. In the neutral position 31C, the supply of hydraulic oil to the hydraulic motor 6 is cut off, so that the hydraulic motor 6 is not rotated and stops.

[0025] 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 (rotational speed) of the hydraulic motor 6 is changed according to the flow rate of the supplied hydraulic oil and the tilt angle of the swash plate of the hydraulic motor 6. The output shaft of the drive device 4, i.e., the output shaft 6a of the hydraulic motor 6, is connected to 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 forward direction and the reverse direction by switching the rotation direction of the hydraulic motor 6.

[0026] In this way, the rotation speed and the rotation direction of the mixer drum 2 are correlated with the rotation speed and the rotation direction of the hydraulic motor 6. Therefore, the controller 20 can calculate (determine) the rotation speed and the rotation direction of the mixer drum 2 based on the rotation information (pulse signal) detected by the rotation sensor 6b and the gear ratio of the reducer 7. That is, the controller 20 calculates the rotation speed of the mixer drum 2 based on the number of pulses of one of the two-phase pulse signals input from the rotation sensor 6b, and determines the rotation direction of the mixer drum 2 based on the phase difference of the two-phase pulse signal. Note that the rotation sensor 6b may be provided on the mixer drum 2 instead of the hydraulic motor 6 to detect the rotation information of the mixer drum 2. In this case, the controller 20 can directly calculate the rotation speed and the rotation direction of the mixer drum 2 from the detection result of the rotation sensor 6b. The rotation speed and the rotation direction of the mixer drum 2 calculated in this way are used for the control of the mixer drum 2 by the controller 20, as described later.

[0027] When the mixer drum 2 is driven to rotate in the forward direction, the fresh concrete in the mixer drum 2 moves forward while being agitated by the drum blades. In this way, by rotating the mixer drum 2 in the forward direction, the fresh concrete in the mixer drum 2 can be agitated. On the other hand, when the mixer drum 2 is driven to rotate in the reverse direction, the fresh concrete in the mixer drum 2 moves backward while being agitated by the drum blades. In this way, by rotating the mixer drum 2 in the reverse direction, the fresh concrete can be discharged from the opening 2a of the mixer drum 2.

[0028] The controller 20 is composed of 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), etc. 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 unit 4 is controlled by operating the CPU, RAM, etc. according to the program stored in the ROM.

[0029] As described above, the controller 20 is connected to the electromagnetic proportional valve 31 and the throttle valve 10a of the engine 10, and outputs a command signal for operating these. Furthermore, the controller 20 is connected to an input unit 40 and a rotation sensor 6b, which are used by an operator to operate the rotation speed and rotation direction of the mixer drum 2. The input unit 40 is, for example, a dial knob-type potentiometer provided in the driver's cab 11 of the mixer vehicle 1, or a terminal wirelessly connected to the controller 20. An operation input by the operator input through the input unit 40 is transmitted to the controller 20 as an operation signal. The operation signal includes information indicating the target rotation speed and target rotation direction of the mixer drum 2 input by the operator.

[0030] The controller 20 calculates (determines) the current rotation speed and rotation direction of the mixer drum 2 in order to control the mixer drum 2. Fig. 3 is a flowchart showing how the controller 20 calculates (determines) the rotation speed and rotation direction of the mixer drum 2. The controller 20 repeatedly executes the process shown in Fig. 3, for example, every time a pulse signal is input from the rotation sensor 6b.

[0031] First, the controller 20 judges whether the rotation sensor 6b is normal based on the two-phase pulse signal input from the rotation sensor 6b. Specifically, in step S101, the controller 20 judges whether a pulse signal of one phase, that is, A-phase, is input from the rotation sensor 6b. If a pulse signal of phase A is input, the controller 20 proceeds to step S102 and judges whether a pulse signal of the other phase, that is, B-phase, is input from the rotation sensor 6b. If a pulse signal of phase B is input, the controller 20 proceeds to step S103 and judges that the rotation sensor 6b is normal, and in step S104, the controller 20 calculates the number of rotations and the direction of rotation of the mixer drum 2 based on the detection result (pulse signal) of the rotation sensor 6b as described above, and ends the process.

[0032] On the other hand, if the A-phase pulse signal is not input from the rotation sensor 6b in step S101, or if the B-phase pulse signal is not input from the rotation sensor 6b in step S102, the controller 20 proceeds to step S105 and determines that the rotation sensor 6b is abnormal. In this way, "the rotation sensor 6b is normal" refers to a state in which the rotation sensor 6b detects both of the two-phase pulse signals, and "the rotation sensor 6b is abnormal" refers to a state in which the rotation sensor 6b detects a pulse signal of one phase but does not detect a pulse signal of the other phase.

[0033] When the rotation sensor 6b is in an abnormal state in which it detects only one of the pulse signals, the controller 20 cannot determine the rotation direction of the mixer drum 2 based on the phase difference between the two-phase pulse signals. That is, the controller 20 cannot determine the rotation direction of the mixer drum 2 based on the detection result of the rotation sensor 6b. In this case, in step S106, the controller 20 determines the rotation direction of the mixer drum 2 based on the command value to the solenoid 32 when rotating the mixer drum 2 in the forward direction and the command value to the solenoid 32 when rotating the mixer drum 2 in the reverse direction (specifically, the current value passed through the first solenoid 32a and the second solenoid 32b). That is, the controller 20 determines that the rotation direction of the mixer drum 2 is the forward direction when the first solenoid 32a is energized, and determines that the rotation direction of the mixer drum 2 is the reverse direction when the second solenoid 32b is energized. Furthermore, the controller 20 calculates the rotation speed of the mixer drum 2 based on the number of pulses of the pulse signal of one phase detected by the rotation sensor 6b. In step S106, after determining the rotation direction of the mixer drum 2 and calculating the rotation speed, the process ends.

[0034] In this way, the detection result of the rotation sensor 6b is used to calculate the rotation speed of the mixer drum 2 by the controller 20, regardless of the state of the rotation sensor 6b. Also, to determine the rotation direction of the mixer drum 2 by the controller 20, if the rotation sensor 6b is normal, the detection result of the rotation sensor 6b is used, and if the rotation sensor 6b is abnormal, the command value to the solenoid 32 is used.

[0035] The controller 20 controls the rotation speed and rotation direction of the mixer drum 2 so that the rotation state of the mixer drum 2 corresponds to the operation signal received from the input unit 40. Specifically, the controller 20 controls the hydraulic pump 5, the hydraulic motor 6, and the solenoid proportional valve 31 so that the rotation speed and rotation direction of the mixer drum 2 correspond to the target rotation speed and target rotation direction received from the input unit 40.

[0036] More specifically, when the controller 20 receives an operation signal from the input unit 40, it calculates the difference between the calculated current rotation speed of the mixer drum 2 and the target rotation speed of the mixer drum 2. Then, the controller 20 changes the amount of electricity supplied to the solenoid 32 of the electromagnetic proportional valve 31 by an amount equivalent to the difference, or controls the throttle valve 10a of the engine 10 to change the rotation speed of the engine 10 by an amount equivalent to the difference, thereby controlling the flow rate of the hydraulic oil supplied to the hydraulic motor 6 and controlling the mixer drum 2 to rotate at the target rotation speed.

[0037] In addition, when the controller 20 receives an operation signal from the input unit 40, it selectively energizes the first solenoid 32a or the second solenoid 32b depending on the current rotation direction of the mixer drum 2 determined based on the detection result of the rotation sensor 6b or the current state of the solenoid 32, and the target rotation direction.

[0038] In this manner, the controller 20 controls the rotation speed and rotation direction of the mixer drum 2. If the controller 20 were configured to calculate (determine) the rotation speed and rotation direction of the mixer drum 2 based only on the rotation sensor 6b, when an abnormality occurs in the rotation sensor 6b and a pulse signal of one phase is not detected, the rotation direction of the mixer drum 2 cannot be determined from the detection result of the rotation sensor 6b, and the mixer drum 2 cannot be accurately controlled. In contrast, the controller 20 determines the rotation direction of the mixer drum 2 from the detection result of the rotation sensor 6b or the command value to the solenoid 32 according to the state of the rotation sensor 6b as described above, and calculates the rotation speed of the mixer drum 2 from the detection result of the rotation sensor 6b regardless of the state of the rotation sensor 6b. Therefore, even if an abnormality occurs in the rotation sensor 6b, the mixer drum 2 can be accurately controlled.

[0039] Furthermore, the result of the determination of the rotation direction of the mixer drum 2 based on the energization state of the solenoid 32 can also be used, for example, to monitor an abnormality in the rotation sensor 6b. Specifically, the controller 20 compares the current rotation direction of the mixer drum 2 determined based on the detection result of the rotation sensor 6b with the current rotation direction of the mixer drum 2 determined based on the energization state of the solenoid 32. If the two are different, the controller 20 detects the abnormality as being due to an abnormality in the rotation sensor 6b and notifies the operator via an alarm unit (such as a buzzer, lamp, or monitor) (not shown) or the like.

[0040] Next, modified examples of the above embodiment will be described. The following modified examples are also within the scope of the present invention, and it is possible to combine the following modified examples with the configuration of the above embodiment, or to combine the following modified examples with each other.

[0041] <Variation 1> In the above embodiment, the controller 20 uses the detection result of the rotation sensor 6b when the rotation sensor 6b is normal, and uses the command value to the solenoid 32 when the rotation sensor 6b is abnormal. This is not limiting, and the controller 20 may always determine the rotation direction of the mixer drum 2 from the command value to the solenoid 32 regardless of the state of the rotation sensor 6b. In other words, the controller 20 may not determine the rotation direction of the mixer drum 2 from the detection result of the rotation sensor 6b. With this configuration, the controller 20 determines the rotation direction of the mixer drum 2 from the energization state of the solenoid proportional valve 31 that controls the flow of the hydraulic oil guided from the hydraulic pump 5 to the hydraulic motor 6, rather than the detection result of a sensor or the like, and therefore the controller 20 can accurately determine the rotation direction of the mixer drum 2 and accurately control the mixer drum 2.

[0042] In this case, it is sufficient that the controller 20 can calculate only the rotation speed of the mixer drum 2 from the detection result of the rotation sensor 6b. Therefore, the rotation sensor 6b may be provided in the engine 10 or the hydraulic pump 5, and the controller 20 may calculate the rotation speed of the engine 10 or the hydraulic pump 5, the flow rate of the hydraulic pump 5, etc. based on the detection result of the rotation sensor 6b, and calculate the rotation speed of the mixer drum 2 based on the calculation result.

[0043] <Variation 2> In the above embodiment, if the rotation sensor 6b is normal, the controller 20 determines the rotation direction of the mixer drum 2 based on the detection result (pulse signal) of the rotation sensor 6b. Without being limited to this, the rotation sensor 6b may determine the rotation direction of the mixer drum 2 based on the pulse signal and output the determination result to the controller 20. In other words, if the rotation sensor 6b is normal, the detection result of the rotation sensor 6b may be used to determine the rotation direction of the mixer drum 2, and the determination of the rotation direction of the mixer drum 2 may be performed by either the controller 20 or the rotation sensor 6b.

[0044] <Variation 3> In the above embodiment, the controller 20 selectively energizes the first solenoid 32a or the second solenoid 32b in accordance with the current rotation direction of the mixer drum 2 and the target rotation direction received from the input unit 40. However, the present invention is not limited to this, and the controller 20 may be configured to selectively energize the first solenoid 32a or the second solenoid 32b in accordance with the target rotation direction without referring to the current rotation direction of the mixer drum 2.

[0045] The configuration, operation, and effects of the embodiment of the present invention configured as above will be described below.

[0046] In the controller 20 as a mixer drum control device that controls the drive device 4 that drives and rotates the mixer drum 2, the drive device 4 has a hydraulic pump 5 as a fluid pressure pump driven by an engine 10 as a drive source and discharging a working fluid, a hydraulic motor 6 as a fluid pressure motor that is operated by the working fluid discharged from the hydraulic pump 5 and drives and rotates the mixer drum 2, and an electromagnetic proportional valve 31 as an electromagnetic valve that controls the flow of the working fluid guided from the hydraulic pump 5 to the hydraulic motor 6. The electromagnetic proportional valve 31 has a solenoid 32 for switching between a forward rotation position 31A where the working fluid discharged by the hydraulic pump 5 is guided to the hydraulic motor 6 so that the mixer drum 2 rotates in the forward rotation direction, and a reverse position 31B where the working fluid discharged by the hydraulic pump 5 is guided to the hydraulic motor 6 so that the mixer drum 2 rotates in the reverse direction. The controller 20 determines the rotation direction of the mixer drum 2 based on a command value to the solenoid 32 when rotating the mixer drum 2 in the forward rotation direction and a command value to the solenoid 32 when rotating the mixer drum 2 in the reverse direction.

[0047] In this configuration, the controller 20 determines the rotation direction of the mixer drum 2 from a command value to the solenoid 32 for switching between the forward rotation position 31A and the reverse rotation position 31B. In other words, the controller 20 determines the rotation direction of the mixer drum 2 from a command value to the solenoid proportional valve 31 that controls the flow of the working fluid guided from the hydraulic pump 5 to the hydraulic motor 6, rather than from the detection result of a sensor or the like. Therefore, the rotation direction of the mixer drum 2 can be accurately determined.

[0048] In addition, to determine the rotation direction of the mixer drum 2, the controller 20 uses the detection result of the rotation sensor 6b, which detects rotation information of the mixer drum 2 or the hydraulic motor 6, if the rotation sensor 6b is normal, and uses the command value to the solenoid 32 if the rotation sensor 6b is abnormal.

[0049] In this configuration, even if an abnormality occurs in the rotation sensor 6b, the rotation direction of the mixer drum 2 can be determined from the command value to the solenoid 32.

[0050] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above-mentioned embodiments. [Explanation of symbols]

[0051] 1... mixer vehicle, 2... mixer drum, 5... hydraulic pump (fluid pressure pump), 6... hydraulic motor (fluid pressure motor), 6b... rotation sensor, 10... engine (driving source), 20... controller (mixer drum control device), 31... solenoid proportional valve (solenoid valve), 31A... forward rotation position, 31B... reverse rotation position, 32... solenoid

Claims

1. A mixer drum control device that controls a drive device that rotates a mixer drum, The drive device is a fluid pressure pump that is driven by a drive source to discharge a working fluid; a fluid pressure motor that is actuated by the working fluid discharged from the fluid pressure pump to rotate the mixer drum; a solenoid valve for controlling a flow of the working fluid guided from the fluid pressure pump to the fluid pressure motor, the solenoid valve has a solenoid for switching between a forward rotation position in which the working fluid discharged by the fluid pressure pump is guided to the fluid pressure motor so that the mixer drum rotates in a forward rotation direction and a reverse rotation position in which the working fluid discharged by the fluid pressure pump is guided to the fluid pressure motor so that the mixer drum rotates in a reverse direction, The mixer drum control device determines the rotation direction of the mixer drum based on a command value to the solenoid when rotating the mixer drum in a forward rotation direction and a command value to the solenoid when rotating the mixer drum in a reverse rotation direction.

2. 2. The mixer drum control device according to claim 1, a rotation sensor that detects rotation information of the mixer drum or the fluid pressure motor, the detection result of the rotation sensor being used to determine the rotation direction of the mixer drum, and a command value to the solenoid being used to determine the rotation direction of the mixer drum, if the rotation sensor is normal.

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