Mixer drum control device

Abstract

To improve the precision of the mixer drum's rotation speed control. [Solution] In the mixer drum control device 20 that controls the drive device 4 that rotates the mixer drum 2, the drive device 4 has a hydraulic pump 5 that is driven by an engine 10 or an electric motor 110 to discharge working fluid and a hydraulic motor 6. The mixer drum control device 20 includes a controller 21 that receives an operation signal including the target rotation speed of the mixer drum 2 and outputs a command value corresponding to the target rotation speed of the engine 10 or electric motor 110 in response to the operation signal. If the target rotation speed of the mixer drum 2 is higher than the stirring rotation speed when stirring the contents loaded in the mixer drum 2, the controller 21 outputs a correction command value that increases the torque of the engine 10 or electric motor 110 as a command value corresponding to the target rotation speed of the engine 10 or electric motor 110.

Description

Technical Field

[0005] , ,

[0003] ,

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

Background Art

[0002] Patent Document 1 discloses a mixer truck including a mixer drum, a drive system of the mixer drum, a controller and an operating device for controlling the drive system. The drive system of the mixer drum includes an engine, a variable displacement pump, a variable displacement motor, and a speed reducer. The variable displacement pump is driven by the engine, and the variable displacement motor is driven by the discharged fluid from the variable displacement pump to drive the mixer drum. The engine is controlled by a rotation speed command signal from the controller according to the target rotation speed of the mixer drum to drive the variable displacement pump (in other words, the mixer drum).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a mixer truck as described in Patent Document 1, for example, when the load of the mixer drum increases due to a large amount of loaded material being loaded on the mixer drum, it becomes difficult to rotate the mixer drum. Therefore, the actual rotation speed of the mixer drum becomes smaller than the target rotation speed, and there is a possibility that the mixer drum cannot be accurately controlled.

[0005] The present invention has been made in view of the above problems, and an object thereof is to improve the control accuracy of the rotation speed of the mixer drum. [[ID=�0]]

Means for Solving the Problems

[0006] The present invention relates to a mixer drum control device for controlling a drive device that rotates a mixer drum, wherein the drive device comprises a fluid pressure pump driven by an engine or electric motor to discharge a working fluid, and a fluid pressure motor driven by the working fluid discharged from the fluid pressure pump to rotate a mixer drum, and the mixer drum control device includes a controller that receives an operation signal including a target rotational speed of the mixer drum and outputs a command value corresponding to the target rotational speed of the engine or electric motor in response to the operation signal, and the controller is characterized in that, if the target rotational speed of the mixer drum is higher than the stirring rotational speed when stirring the load loaded on the mixer drum, it outputs a correction command value that increases the torque of the engine or electric motor as a command value corresponding to the target rotational speed of the engine or electric motor.

[0007] In this invention, if the controller's mixer drum's target rotational speed is higher than the stirring speed, it outputs a correction command value that increases the torque of the engine or electric motor, corresponding to the target rotational speed of the engine or electric motor. In other words, if under normal control the actual rotational speed of the mixer drum may be lower than the target rotational speed, the correction command value controls the engine or electric motor to rotate at a higher speed than usual. As a result, the control accuracy of the mixer drum's rotational speed is improved.

[0008] The present invention further comprises a detector that detects information regarding the weight of the load and outputs it to a controller, wherein the controller outputs a correction command value when the target rotation speed of the mixer drum is higher than the stirring rotation speed and the detector detects a load exceeding a predetermined level.

[0009] The present invention is characterized in that the controller has an acquisition unit that acquires property data of the loaded material, and the controller outputs a correction command value when the target rotation speed of the mixer drum is higher than the stirring rotation speed and the property data satisfies predetermined conditions.

[0010] In these inventions, even when engine torque is insufficient due to the weight or properties of the load, and the actual rotational speed of the mixer drum may fall below the target rotational speed under normal control, the engine or electric motor rotational speed is controlled to be higher than normal by a correction command value. As a result, the control accuracy of the mixer drum rotational speed is improved.

[0011] The present invention is characterized in that, when the target rotational speed of the mixer drum exceeds a predetermined value, the controller outputs a command value instead of a correction command value.

[0012] In this invention, the safety of the mixer drum control device can be improved by using command value control when the mixer drum rotates at an unnecessarily high speed due to control using a correction command value.

[0013] The present invention is characterized in that the controller outputs a correction command value when the target rotational speed of the mixer drum is higher than the stirring rotational speed, and the rotational speed of the engine corresponding to the target rotational speed is 2000 rpm or less.

[0014] In this invention, in a region where the actual rotational speed of the mixer drum is likely to be lower than the target rotational speed under normal control, a correction command value is used to control the rotational speed of the engine or electric motor to be higher than normal. As a result, the control accuracy of the mixer drum's rotational speed is improved. [Effects of the Invention]

[0015] According to the present invention, the control accuracy of the rotation speed of the mixer drum is improved. [Brief explanation of the drawing]

[0016] [Figure 1A] This is a plan view of a mixer truck as seen from above, according to an embodiment of the present invention. [Figure 1B] This is a rear view of a mixer car as seen from the rear, according to an embodiment of the present invention. [Figure 2]It is a block diagram showing the hardware configuration of a mixer truck according to an embodiment of the present invention. [Figure 3] It is a diagram showing the relationship between the engine speed and the corresponding governor voltage. [Figure 4] It is a block diagram showing the hardware configuration according to Modification 1 of the embodiment of the present invention. [Figure 5] It is a block diagram showing the hardware configuration according to Modification 2 of the embodiment of the present invention.

Embodiments for Carrying out the Invention

[0017] Hereinafter, a mixer truck provided with a mixer drum control device according to an embodiment of the present invention will be described with reference to the drawings.

[0018] The mixer truck 1 is a vehicle that transports so-called ready-mixed concrete (hereinafter referred to as "ready-mix"), such as mortar and ready-mixed concrete, loaded into the mixer drum 2. In the present embodiment, the mixer truck 1 is a medium-sized or small-sized vehicle, rather than a large vehicle with a large loading capacity. In the following description, the case where the mixer truck 1 loads and transports ready-mix will be described.

[0019] As shown in FIGS. 1A and 1B, the mixer truck 1 is a vehicle including a cab 11 and a chassis 3. The mixer truck 1 includes a mixer drum 2 rotatably mounted on the vehicle, a drive device 4 that rotationally drives the mixer drum 2, and a mixer drum control device 20 that controls the drive device 4.

[0020] The mixer drum 2 is a bottomed cylindrical container rotatably mounted on the chassis 3, and an opening 2a for loading and discharging ready-mix is provided at the rear end thereof. The mixer drum 2 is mounted so that its rotation axis O is inclined so as to gradually rise 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 by rotating the drum blade together with the mixer drum 2, stirring of the ready-mix loaded in the mixer drum 2 is performed.

[0021] A hopper 16 is provided at the upper rear of the opening 2a of the mixing drum 2. The green concrete put into the mixer truck 1 at the ready-mixed concrete plant is led 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 mixing drum 2. The green concrete discharged from the opening 2a is led to the chute 18 by the flow guide 17 and discharged in a predetermined direction by the chute 18.

[0022] The mixing drum 2 is rotationally driven via a drive device 4 using a traveling engine 10 mounted on the mixer truck 1 as a drive source. The drive device 4 is driven by the rotation of the engine 10 and is a hydraulic device that rotationally drives the mixing drum 2 by the hydraulic pressure of the working fluid. In the drive device 4, hydraulic oil is used as the working fluid, but other incompressible fluids may be used as the working fluid. The rotation of the engine 10 is transmitted to the drive device 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 device 4.

[0023] As shown in FIG. 2, the engine 10 has a throttle valve 10a for adjusting the output and rotational speed of the engine 10. By controlling the opening degree of the throttle valve 10a, the output and rotational speed of the engine 10 are adjusted. An electronic governor 15 as an engine regulator having an actuator (not shown) for opening and closing the throttle valve 10a is connected to the throttle valve 10a. The electronic governor 15 is connected to a controller 21 of the mixing drum control device 20 and is controlled by the controller 21. The actuator is driven by the governor voltage as the output of the electronic governor 15, and the throttle valve 10a is opened and closed. By controlling the opening degree of the throttle valve 10a by the controller 21 through the electronic governor 15, the output and rotational speed of the engine 10 are adjusted. Thereby, the drive of the mixing drum 2 is controlled through the drive device 4. Details of the control by the controller 21 will be described later.

[0024] The drive unit 4 includes a hydraulic pump 5, which is a fluid pressure pump driven by the engine 10 as a drive source and discharges hydraulic oil as a working fluid; a hydraulic motor 6, which is a fluid pressure motor that is operated by the hydraulic oil discharged from the hydraulic pump 5 and rotates the mixer drum 2; and an electromagnetic proportional valve 31 that controls the flow of hydraulic oil guided from the hydraulic pump 5 to the hydraulic motor 6. The drive unit 4 can rotate the mixer drum 2 in the forward and reverse directions, and can also change the rotation speed. In this embodiment, the "forward direction" is the mixing direction for stirring the ready-mix concrete and the input direction for pouring in the ready-mix concrete, and the "reverse direction" is the discharge direction for discharging the ready-mix concrete.

[0025] The hydraulic pump 5 is rotationally driven by power constantly supplied from the engine 10 via the PTO shaft 9. The hydraulic pump 5 is a variable-capacity swashplate type axial piston pump. The hydraulic pump 5 can be any type of pump with a variable discharge capacity. The hydraulic fluid discharged from the hydraulic pump 5 is supplied to the hydraulic motor 6.

[0026] The hydraulic motor 6 is a variable-capacity swashplate type axial piston motor, and is rotationally driven by the supply of hydraulic fluid discharged from the hydraulic pump 5. The hydraulic motor 6 is equipped with a solenoid valve (not shown) that receives a two-speed switching signal from the controller 21 of the mixer drum control device 20 and adjusts the tilt angle of the swashplate (not shown). The capacity of the hydraulic motor 6 can be switched between two stages by switching the solenoid valve: a small capacity (2nd speed) for high-speed rotation and a large capacity (1st speed) for normal rotation. The hydraulic motor 6 may also be one whose capacity can be switched steplessly. The rotation of the hydraulic motor 6 is transmitted to the mixer drum 2 via the reduction gear 7. A rotation sensor 6b is provided on the output shaft 6a of the hydraulic motor 6 to detect the rotation state of the hydraulic motor 6 and to monitor the rotation state of the mixer drum 2 as described later. The rotation sensor 6b outputs the detection result to the controller 21 of the mixer drum control device 20.

[0027] A closed circuit L is provided between the hydraulic pump 5 and the hydraulic motor 6, and hydraulic fluid 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 that guides the hydraulic fluid discharged by the hydraulic pump 5 to the hydraulic motor 6 so that the mixer drum 2 rotates in the forward direction, a reverse rotation position 31B that guides the hydraulic fluid discharged by the hydraulic pump 5 to the hydraulic motor 6 so that the mixer drum 2 rotates in the reverse direction, and a neutral position 31C that blocks the flow of hydraulic fluid between the hydraulic pump 5 and the hydraulic motor 6.

[0028] The electromagnetic proportional valve 31 is electronically controlled by the controller 21 of the mixer drum control device 20 and includes a solenoid 32 for switching between a forward rotation position 31A and a reverse rotation position 31B, and a pair of return springs 33a and 33b. The solenoid 32 includes a first solenoid 32a for switching the electromagnetic proportional valve 31 to the forward rotation position 31A, and a second solenoid 32b for switching the electromagnetic proportional valve 31 to the reverse rotation position 31B. When the first solenoid 32a is energized, the electromagnetic proportional valve 31 switches to the forward rotation position 31A and supplies hydraulic fluid to the hydraulic motor 6 to rotate the mixer drum 2 in the forward direction. When the second solenoid 32b is energized, the electromagnetic proportional valve 31 switches to the reverse rotation position 31B and supplies hydraulic fluid to the hydraulic motor 6 to rotate the mixer drum 2 in the reverse direction. The first solenoid 32a and the second solenoid 32b are operated by command values ​​(specifically, current values) output from the controller 21. By adjusting the current values ​​output to the first solenoid 32a and the second solenoid 32b, the electromagnetic proportional valve 31 can be switched between forward rotation position 31A, neutral position 31C, and reverse rotation position 31B.

[0029] The electromagnetic proportional valve 31 is switched to the forward rotation position 31A when the first solenoid 32a is energized. This supplies hydraulic fluid to the hydraulic motor 6 so that it rotates the mixer drum 2 in the forward direction. Conversely, the electromagnetic proportional valve 31 is switched to the reverse rotation position 31B when the second solenoid 32b is energized. This supplies hydraulic fluid to the hydraulic motor 6 so that it rotates the mixer drum 2 in the reverse direction. When the power to the first solenoid 32a and the second solenoid 32b is cut off, the electromagnetic proportional valve 31 is switched to the neutral position 31C by the biasing force of a pair of return springs 33a and 33b. In the neutral position 31C, the supply of hydraulic fluid to the hydraulic motor 6 is cut off, so the hydraulic motor 6 is not driven to rotate and stops.

[0030] In the drive unit 4 configured as described above, the engine 10 drives the hydraulic pump 5, and the hydraulic fluid discharged from the hydraulic pump 5 is supplied to the hydraulic motor 6, causing the hydraulic motor 6 to rotate. The rotational speed of the hydraulic motor 6 is changed according to the flow rate of the supplied hydraulic fluid and the tilt angle of the swash plate of the hydraulic motor 6. The output shaft of the drive unit 4, i.e., the output shaft 6a of the hydraulic motor 6, is connected to the mixer drum 2 via a reduction gear 7. Therefore, by increasing or decreasing the rotational speed of the hydraulic motor 6, it is possible to increase or decrease the rotational speed of the mixer drum 2, and by switching the rotation direction of the hydraulic motor 6, it is possible to switch the rotation direction of the mixer drum 2 between forward and reverse rotation. In other words, by increasing or decreasing the rotational speed of the engine 10 by controlling the opening degree of the throttle valve 10a, it is possible to increase or decrease the rotational speed of the mixer drum 2, and by switching the flow of hydraulic fluid to the hydraulic motor 6 by controlling the electromagnetic proportional valve 31, it is possible to switch the rotation direction of the mixer drum 2 between forward and reverse rotation.

[0031] Thus, the rotational state of the mixer drum 2 (specifically, the rotational speed and direction) correlates with the rotational state of the hydraulic motor 6. Therefore, the controller 21 can calculate the rotational state of the mixer drum 2 based on the rotational state of the hydraulic motor 6 detected by the rotation sensor 6b and the gear ratio of the reduction gear 7. The calculated rotational state of the mixer drum 2 is displayed on a display unit (not shown), for example, provided together with the operation unit 40 described later, so that the user can confirm it. In this way, the rotational state of the mixer drum 2 is monitored. Note that the rotation sensor 6b may be provided on the mixer drum 2 instead of the hydraulic motor 6 to directly detect (calculate) the rotational state of the mixer drum 2.

[0032] When the mixer drum 2 is driven to rotate in the forward direction, the ready-mixed concrete inside the mixer drum 2 moves forward while being agitated by the drum blades. In other words, the ready-mixed concrete inside the mixer drum 2 can be agitated by rotating it in the forward direction. On the other hand, when the mixer drum 2 is driven to rotate in the reverse direction, the ready-mixed concrete inside the mixer drum 2 moves backward while being agitated by the drum blades. In this way, the ready-mixed concrete can be discharged from the opening 2a of the mixer drum 2 by rotating it in the reverse direction.

[0033] Next, the configuration of the mixer drum control device 20 will be described in detail.

[0034] The mixer drum control device 20 includes a controller 21 that outputs a command value corresponding to the target rotational speed of the engine 10 and controls the rotation of the engine 10 by means of a governor voltage as the output of the electronic governor 15, and a pressure sensor 22 provided on the hydraulic pump 5 that detects the discharge pressure of the hydraulic pump 5.

[0035] The controller 21 consists of a microcomputer equipped with a CPU (Central Processing Unit), ROM (Read-Only Memory), RAM (Random Access Memory), and an I / O interface (Input / Output Interface). The RAM stores data from the CPU's processing, the ROM stores control programs for the CPU in advance, and the I / O interface is used for inputting and outputting information with 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.

[0036] The controller 21 is connected to an electronic governor 15 and a solenoid proportional valve 31. Furthermore, the controller 21 is connected to an operating unit 40 for the user to operate the mixer drum 2 and a rotation sensor 6b. The operating unit 40 is, for example, an operating panel installed in the driver's cab 11 of the mixer truck 1, or a terminal wirelessly connected to the controller 21, and has a plurality of push-button type switches (not shown) corresponding to operations such as loading, stirring (specifically, stirring while moving), mixing, discharge, and washing. When any of the switches on the operating unit 40 is pressed, the controller 21 sets the target rotation speed and target rotation direction of the mixer drum 2 according to the switch, and information indicating the target rotation speed and target rotation direction is transmitted to the controller 21 as an operation signal. The controller 21 outputs a command signal (command value) to control the electronic governor 15 and the solenoid proportional valve 31 according to the operation signal output from the operating unit 40. The operating unit 40 is not limited to the switches described above; it may also include, for example, a dial-type potentiometer that allows selection of operations such as adding, stirring, kneading, discharging, and washing.

[0037] The pressure sensor 22 detects the load on the hydraulic pump 5 by detecting the discharge pressure of the hydraulic pump 5. The discharge pressure of the hydraulic pump 5 changes depending on the weight of the load on the mixer drum 2. The heavier the load on the mixer drum 2, the greater the discharge pressure of the hydraulic pump 5. Also, the discharge pressure of the hydraulic pump 5 increases when concrete is being poured in, when discharge begins, and when the rotation direction of the mixer drum 2 is changed. Therefore, by detecting the discharge pressure of the hydraulic pump 5 with the pressure sensor 22, it is possible to detect whether there is a load on the mixer drum 2 and the load required to rotate the mixer drum 2. In other words, the pressure sensor 22 is a detector that detects information regarding the weight of the load on the mixer drum 2. The detection result of the pressure sensor 22 is output to the controller 21.

[0038] Next, we will explain in detail how the controller 21 controls the mixer drum 2.

[0039] For example, when the user presses the mixing switch on the control unit 40 to mix the ready-mix concrete loaded in the mixer drum 2 (specifically, to mix the ready-mix concrete while it is moving), the target rotation speed is set to a low value such as 1 rpm, and the target rotation direction is set to the forward direction. Hereafter, the target rotation speed when mixing the loaded material (ready-mix concrete) as described above will also be simply referred to as the "mixing rotation speed." When the user presses the input switch on the control unit 40 to put ready-mix concrete into the mixer drum 2, or when the user presses the mixing switch on the control unit 40 to mix the put-in ready-mix concrete, the target rotation speed is set to a higher value than the mixing rotation speed, and the target rotation direction is set to the forward direction, in order to actively mix the ready-mix concrete. Also, when the user presses the discharge switch on the control unit 40 to discharge ready-mix concrete from the mixer drum 2, or when the user presses the cleaning switch on the control unit 40 to clean the mixer drum 2, the target rotation speed is set to a higher value than the mixing rotation speed, and the target rotation direction is set to the reverse direction. During the cleaning of mixer drum 2, the load will be "cleaning water." Thus, when performing input, mixing, discharge, and cleaning operations, the target rotational speed of mixer drum 2 will be higher than the stirring rotational speed.

[0040] When a user presses a switch on the control unit 40 and an operation signal indicating the target rotation speed and target rotation direction of the mixer drum 2 is output to the controller 21, the controller 21 controls the rotation speed and rotation direction of the mixer drum 2 so that the rotation state of the mixer drum 2 is in accordance with the operation signal received from the control unit 40. Specifically, the controller 21 controls the electronic governor 15 so that the rotation speed of the mixer drum 2 becomes the target rotation speed output from the control unit 40, and controls the electromagnetic proportional valve 31 so that the rotation direction of the mixer drum 2 becomes the target rotation direction output from the control unit 40. The electromagnetic proportional valve 31 is controlled by selectively energizing either the corresponding first solenoid 32a or the second solenoid 32b.

[0041] The control of the electronic governor 15 will be explained in detail. The controller 21 stores, for example, a map, the relationship between the rotational speed of the mixer drum 2 and the rotational speed of the engine 10 required to achieve that rotational speed. Furthermore, as shown by A in the graph of Figure 3, the controller 21 also stores, for example, a map, the relationship between the rotational speed of the engine 10 and the governor voltage output by the electronic governor 15 to achieve that rotational speed. The above map is set for each mixer vehicle 1, taking into account the torque characteristics of the engine 10, and is determined, for example, experimentally. In this embodiment, the larger the governor voltage, the larger the opening of the throttle valve 10a, and the higher the rotational speed of the engine 10 and the rotational speed of the mixer drum 2. With the above two maps, there is a one-to-one correspondence between the numerical value of the rotational speed of the mixer drum 2 and the numerical value of the governor voltage.

[0042] For example, when a user presses the stirring switch on the control unit 40 and a low stirring speed is set as the target rotation speed, the controller 21 calculates the rotation speed of the engine 10 corresponding to the stirring speed based on the relationship between the stored rotation speed of the mixer drum 2 and the rotation speed of the engine 10. Next, it calculates the governor voltage corresponding to the engine speed of the engine 10 calculated above based on the relationship between the stored rotation speed of the engine 10 and the governor voltage (point C shown in Figure 3). Then, the controller 21 outputs a command value to the electronic governor 15 to output the calculated governor voltage, thereby controlling the rotation speed of the engine 10. In this way, the rotation speed of the mixer drum 2 is controlled to become the stirring speed.

[0043] In the mixer truck 1, if the load on the mixer drum 2 increases, for example, when a large amount of material is loaded onto the mixer drum 2, it becomes difficult to rotate the mixer drum 2. As a result, the actual rotational speed of the mixer drum 2 becomes smaller than the target rotational speed, and there is a risk that the mixer drum 2 cannot be accurately controlled. In particular, in a medium-sized or small mixer truck 1 like the one in this embodiment, the torque of the engine 10 is smaller than that of a large truck, so even with a small amount of material loaded, the actual rotational speed of the mixer drum 2 becomes smaller than the target rotational speed. In the low rotational speed range of the engine 10, the torque of the engine 10 is small, making it even more difficult to rotate the mixer drum 2. In addition, when performing operations that require a higher rotational speed than the agitation of the mixer drum 2, such as loading, mixing, discharge, and washing, the difference between the target rotational speed and the actual rotational speed of the mixer drum 2 tends to become large.

[0044] Therefore, in this embodiment, if the rotational speed (target rotational speed) of the mixer drum 2 is higher than the stirring rotational speed, the controller 21 controls the rotation of the engine 10 by adjusting the governor voltage to increase the torque of the engine 10, thereby rotating the mixer drum 2. In other words, if the target rotational speed of the mixer drum 2 is higher than the stirring rotational speed, the controller 21 outputs a correction command value that increases the torque of the engine 10 as a command value corresponding to the target rotational speed of the engine 10.

[0045] Graph B in Figure 3 shows the relationship between the rotational speed of the engine 10 and the corresponding corrected governor voltage when the load on the mixer drum 2 increases. The corrected governor voltage is a value obtained by correcting the governor voltage to a higher value so that the torque of the engine 10 increases so that the mixer drum 2 can be rotated at the target rotational speed even when the load on the mixer drum 2 increases. Specifically, the controller 21 stores in advance, for example as a map, the relationship between the rotational speed of the engine 10 and the sum value used to correct the governor voltage to the corrected governor voltage when the load on the mixer drum 2 increases (in other words, the relationship between the rotational speed of the engine 10 and the corrected governor voltage). The above map is set for each mixer truck 1 considering the torque characteristics of the engine 10 and is determined experimentally, for example. In this embodiment, the corrected governor voltage is set in a range from a rotational speed higher than the engine rotational speed corresponding to the stirring rotation (point C in Figure 3) to approximately 2000 rpm or less. Thus, the controller 21 stores two sets of data: the relationship between the engine speed 10 and the governor voltage for normal control, and the relationship between the engine speed 10 and the corrected governor voltage for corrective control that increases the torque of the engine 10 compared to normal.

[0046] When the controller 21 receives an operation signal from the operation unit 40, it determines whether the rotational speed (target rotational speed) of the mixer drum 2 is higher than the stirring rotational speed stored in advance. If the target rotational speed of the mixer drum 2 is higher than the stirring rotational speed, the controller 21 calculates the rotational speed of the engine 10 corresponding to the target rotational speed of the mixer drum 2 from the relationship between the stored rotational speed of the mixer drum 2 and the rotational speed of the engine 10, and calculates the governor voltage corresponding to the rotational speed of the engine 10 calculated above from the relationship between the stored rotational speed of the engine 10 and the governor voltage. Then, from the relationship between the stored rotational speed of the engine 10 and the summation value for correcting the governor voltage to a corrected governor voltage, the controller 21 adds the summation value corresponding to the rotational speed of the engine 10 to the governor voltage and calculates the corrected governor voltage. After that, it outputs the correction command value as a command value to the electronic governor 15 to output the calculated corrected governor voltage and controls the rotational speed of the engine 10. In this way, the rotational speed of the mixer drum 2 is controlled to become the target rotational speed. In other words, if the target rotation speed of the mixer drum 2 is higher than the stirring speed, the controller 21 switches from control using the normal governor voltage to corrected control using a corrected governor voltage. If the target rotation speed is less than or equal to the stirring speed, the controller 21 calculates the normal, uncorrected governor voltage as described above for the stirring speed.

[0047] Thus, when the rotational speed of the mixer drum 2 (target rotational speed) is higher than the stirring rotational speed, the controller 21 outputs a correction command value that increases the torque of the engine 10 as a command value corresponding to the target rotational speed. In other words, under normal control, if the actual rotational speed of the mixer drum 2 may be lower than the target rotational speed, the correction command value controls the rotational speed of the engine 10 to be higher than normal. As a result, the control accuracy of the rotational speed of the mixer drum 2 is improved.

[0048] Furthermore, in a configuration where the controller 21 calculates the current rotational speed of the mixer drum 2 from the detected value of the rotation sensor 6b provided on the hydraulic motor 6 and controls the rotational speed of the mixer drum 2 from the difference between that value and the target rotational speed, if the rotation sensor 6b fails and the detected value becomes zero, the mixer drum 2 cannot be controlled. In contrast, in this embodiment, the rotation sensor 6b is used only to monitor the rotational state of the mixer drum 2, and the controller 21 controls the rotational speed of the mixer drum 2 using a command value or correction command value corresponding to the target rotational speed. Therefore, even if the rotation sensor 6b fails, the mixer drum 2 can be controlled.

[0049] Furthermore, in this embodiment, the corrected governor voltage is set within a range where the engine speed is approximately 2000 rpm or less. In other words, the controller 21 controls the rotation of the engine 10 by the corrected governor voltage when the target rotation speed is higher than the stirring rotation speed and the rotation speed of the engine 10 corresponding to the target rotation speed of the mixer drum 2 is 2000 rpm or less. It was confirmed that even when the load on the mixer drum 2 increases, if the torque of the engine 10 increases, the difference between the target rotation speed and the actual rotation speed of the mixer drum 2 becomes smaller even when the rotation of the mixer drum 2 is controlled with the normal, uncorrected governor voltage, and the difference almost disappears at 2000 rpm. Therefore, in this way, in the region (2000 rpm or less) where the actual rotation speed of the mixer drum 2 is likely to be lower than the target rotation speed under normal control, the control accuracy of the rotation speed of the mixer drum 2 is improved by controlling the rotation speed of the engine 10 to a higher rotation speed than usual using the corrected governor voltage. In particular, the effect of improving the control accuracy of the mixer drum 2's rotational speed is significant in the range where the engine speed is 1500 rpm or less. Furthermore, in the range where the engine speed of the engine 10 is greater than 2000 rpm, controlling the rotation of the engine 10 without correcting the governor voltage improves the control accuracy of the mixer drum 2's rotational speed while also improving the fuel efficiency of the mixer vehicle 1.

[0050] Furthermore, as shown in Figure 3 for engine speed D of engine 10, in regions where the torque of engine 10 is relatively high (for example, in regions exceeding 800 Nm), it was confirmed that even when controlling the rotation of the mixer drum 2 with the normal, uncorrected governor voltage, the difference between the target rotation speed and the actual rotation speed of the mixer drum 2 gradually decreases as the engine speed increases. Therefore, the corrected governor voltage is set so that the difference with the governor voltage gradually decreases in regions above the rotation speed D mentioned above.

[0051] Furthermore, if no material is loaded onto the mixer drum 2, the load on the mixer drum 2 will not increase. Therefore, the controller 21 may perform the above processing only when material is loaded onto the mixer drum 2 (specifically, when the detected value of the pressure sensor 22 is higher than a predetermined value). However, when performing operations with a rotational speed higher than the stirring speed of the mixer drum 2, such as loading, mixing, discharge, and washing (in other words, when the target rotational speed is higher than the stirring rotational speed), material is usually loaded onto the mixer drum 2. Therefore, it is not essential to determine whether or not material is loaded onto the mixer drum 2, nor is the pressure sensor 22 required for this determination an essential component. Furthermore, when mixer drum 2 is loaded with cleaning water, such as during cleaning of mixer drum 2, the load on mixer drum 2 is less with cleaning water than with ready-mix concrete. Therefore, the above process may be omitted when mixer drum 2 is being cleaned (the detection value of the pressure sensor 22 corresponding to the cleaning of mixer drum 2), and only performed when ready-mix concrete is loaded onto mixer drum 2.

[0052] Furthermore, if the controller 21's target rotational speed of the mixer drum 2 exceeds a predetermined value (for example, if it reaches a high rotational speed of 20 rpm or more), it may output the governor voltage as the command value instead of the corrected governor voltage (corrected command value). Controlling with the governor voltage when the mixer drum 2 rotates at an unnecessarily high speed using corrected governor voltage can improve the safety of the mixer drum control device 20.

[0053] According to the above embodiment, the following effects are achieved.

[0054] The controller 21 outputs a correction command value that increases the torque of the engine 10 if the target rotational speed of the mixer drum 2 is higher than the stirring rotational speed. In other words, if under normal control there is a possibility that the actual rotational speed of the mixer drum 2 will be lower than the target rotational speed, the correction command value controls the rotational speed of the engine 10 to be higher than normal. As a result, the control accuracy of the rotational speed of the mixer drum 2 is improved.

[0055] Next, modifications of the above embodiment will be described. The following modifications are also within the scope of the present invention, and it is possible to combine the following modifications with the configuration of the above embodiment, or to combine the following modifications with each other.

[0056] <Example 1> In the above embodiment, the mixer truck 1 is a medium-sized or small truck, and the controller 21 outputs a correction command value and controls the rotation of the engine 10 with a correction governor voltage when the target rotation speed of the mixer drum 2 is higher than the stirring rotation speed. However, the mixer truck 1 is not limited to this and may be a large truck with a large load capacity. In this case, the torque of the engine 10 is higher than that of medium-sized and small trucks, and when the load capacity is small, there is almost no difference between the target rotation speed and the actual rotation speed of the mixer drum 2. For this reason, the controller 21 may control the rotation of the engine 10 with a correction governor voltage when the target rotation speed of the mixer drum 2 is higher than the stirring rotation speed, as in this embodiment, but it is preferable to output a correction command value and control the rotation of the engine 10 with a correction governor voltage when the target rotation speed of the mixer drum 2 is higher than the stirring rotation speed and the load capacity is greater than a predetermined weight (specifically, when the detected value of the pressure sensor 22 is higher than a predetermined value). In other words, it is preferable that the controller 21 outputs a correction command value and controls the rotation of the engine 10 when the load on the mixer drum 2 increases to such an extent that the actual rotation speed of the mixer drum 2 becomes smaller than the target rotation speed.

[0057] Furthermore, if the mixer truck 1 is a large vehicle, the controller 21 may have an acquisition unit 21a that acquires property data of the loaded material, as shown in Figure 4. The property data indicates, for example, the material and ratio of the ready-mix concrete that is the loaded material. The acquisition unit 21a can communicate with, for example, the operation unit 40, and acquires property data input to or stored in an external device such as the operation unit 40 by communication. In this case, the controller 21 outputs a correction command value and controls the rotation of the engine 10 with a correction governor voltage when the target rotation speed is higher than the mixing rotation speed and the property data satisfies predetermined conditions. Here, "predetermined conditions" are conditions in which the load on the mixer drum 2 increases to the extent that the actual rotation speed of the mixer drum 2 becomes smaller than the target rotation speed, such as when the ratio of hard materials such as aggregate is higher than a predetermined value. Furthermore, regarding control based on property data and the load amount of the above-mentioned cargo, for example, a map relating the target rotational speed of the mixer drum 2 and the corrected governor voltage may be created for each load amount, and the corrected governor voltage (corrected command value) may be calculated and output based on the map corresponding to the load amount. This further improves the control accuracy of the rotational speed of the mixer drum 2.

[0058] In these configurations, even if the engine torque is somewhat insufficient due to the weight and characteristics of the load, and the actual rotational speed of the mixer drum 2 may fall below the target rotational speed under normal control, the correction command value controls the engine 10 to rotate at a higher speed than normal. As a result, the control accuracy of the rotational speed of the mixer drum 2 is improved.

[0059] <Modification 2> In the above embodiment, the hydraulic pump 5 is driven by the engine 10 as the drive source, and the controller 21 controls the rotational speed of the engine 10. However, as shown in Figure 5, the hydraulic pump 5 may be driven by an electric motor 110 as the drive source, and the controller 21 may control the rotational speed of the electric motor 110. In this configuration, the PTO shaft 9 is rotated by the electric motor 110. The controller 21 is connected to the electric motor 110 and, similar to the above embodiment, outputs a command value corresponding to the target rotational speed of the electric motor 110 and a correction command value that increases the torque of the electric motor 110 to the electric motor 110, thereby controlling the rotational speed of the electric motor 110. Even with this configuration, the same effects as in the above embodiment are achieved.

[0060] <Variation 3> In the above embodiment, a pressure sensor 22 is provided as a detector to detect information regarding the weight of the load loaded on the mixer drum 2, and the pressure sensor 22 detects the load of the hydraulic pump 5 by detecting the discharge pressure of the hydraulic pump 5. However, the detector for detecting information regarding the weight of the load loaded on the mixer drum 2 is not limited to the pressure sensor 22. For example, a flow sensor may be provided on the hydraulic pump 5 as a detector to detect the load from the flow rate of the hydraulic pump 5, or a weight sensor may be provided on the mixer drum 2 as a detector to directly detect the weight of the load on the mixer drum 2. In these cases, the controller 21 should output a correction command value when a detector such as the pressure sensor 22, flow sensor, or weight sensor detects a load above a predetermined level.

[0061] <Modification 4> In the above embodiment, the controller 21 stores a map showing the relationship between the rotational speed of the engine 10 and an added value used to correct the governor voltage to a corrected governor voltage, for performing corrective control to increase the torque of the engine 10 compared to normal. The added value calculated from the map is added to the governor voltage to calculate the corrected governor voltage. However, the method of calculating the corrected governor voltage is not limited to this. For example, the relationship between the rotational speed of the engine 10 and the corrected governor voltage may be stored as a map, and the corrected governor voltage may be calculated from the map. Alternatively, the corrected governor voltage may be calculated by multiplying the governor voltage by a predetermined coefficient.

[0062] The configuration, operation, and effects of the embodiment of the present invention configured as described above will be summarized below.

[0063] The mixer drum control device 20 controls the drive unit 4 that rotates the mixer drum 2. The drive unit 4 includes a hydraulic pump 5, which is a fluid pressure pump driven by the engine 10 or electric motor 110 to discharge working fluid, and a hydraulic motor 6, which is a fluid pressure motor driven by the working fluid discharged from the hydraulic pump 5 to rotate the mixer drum 2. The mixer drum control device 20 includes a controller 21 that receives an operation signal including the target rotational speed of the mixer drum 2 and outputs a command value corresponding to the target rotational speed of the engine 10 or electric motor 110 in response to the operation signal. If the target rotational speed of the mixer drum 2 is higher than the stirring rotational speed when stirring the contents loaded on the mixer drum 2, the controller 21 outputs a correction command value that increases the torque of the engine 10 or electric motor 110 as a command value corresponding to the target rotational speed of the engine 10 or electric motor 110.

[0064] In this configuration, if the controller 21's target rotational speed of the mixer drum 2 is higher than the stirring speed, it outputs a correction command value that increases the torque of the engine 10 or electric motor 110, corresponding to the target rotational speed of the engine 10 or electric motor 110. In other words, if under normal control the actual rotational speed of the mixer drum 2 may be lower than the target rotational speed, the correction command value controls the rotational speed of the engine 10 or electric motor 110 to be higher than normal. As a result, the control accuracy of the mixer drum 2's rotational speed is improved.

[0065] Furthermore, the mixer drum control device 20 is further equipped with a detector (pressure sensor 22) that detects information regarding the weight of the load and outputs it to the controller 21. The controller 21 outputs a correction command value when the target rotation speed of the mixer drum 2 is higher than the stirring rotation speed and the detector detects a load above a predetermined level.

[0066] Furthermore, in the mixer drum control device 20, the controller 21 has an acquisition unit 21a that acquires property data of the loaded material, and the controller 21 outputs a correction command value when the target rotation of the mixer drum 2 is higher than the stirring rotation speed and the property data satisfies predetermined conditions.

[0067] In these configurations, even if the engine torque is somewhat insufficient due to the weight and characteristics of the load, and the actual rotational speed of the mixer drum 2 may be lower than the target rotational speed under normal control, the correction command value controls the rotational speed of the engine 10 or electric motor 110 to be higher than normal. As a result, the control accuracy of the rotational speed of the mixer drum 2 is improved.

[0068] Furthermore, in the mixer drum control device 20, the controller 21 outputs a command value instead of a correction command value when the target rotation speed of the mixer drum 2 exceeds a predetermined value.

[0069] In this configuration, the safety of the mixer drum control device 20 can be improved by using command value control when the mixer drum 2 rotates at an unnecessarily high speed due to control using the correction command value.

[0070] Furthermore, in the mixer drum control device 20, the controller 21 outputs a correction command value if the target rotation speed is higher than the stirring rotation speed and the rotation speed of the engine 10 corresponding to the target rotation speed is 2000 rpm or less.

[0071] In this configuration, in areas where the actual rotational speed of the mixer drum 2 is likely to be lower than the target rotational speed under normal control, the engine 10 or electric motor 110 is controlled by a correction command value to ensure that its rotational speed is higher than normal. As a result, the control accuracy of the mixer drum 2's rotational speed is improved.

[0072] Although embodiments of the present invention have been described above, these embodiments only represent a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments. [Explanation of Symbols]

[0073] 1…Mixer truck, 2…Mixer drum, 4…Drive unit, 5…Hydraulic pump (fluid pressure pump), 6…Hydraulic motor (fluid pressure motor), 10…Engine, 20…Mixer drum control device, 21…Controller, 21a…Acquisition unit, 22…Pressure sensor (detector), 110…Electric motor

Claims

1. A mixer drum control device that controls the drive device that rotates the mixer drum, The drive device is A fluid pressure pump that is driven by an engine or electric motor to discharge a working fluid, The system includes a fluid pressure motor that operates using the working fluid discharged from the fluid pressure pump to rotate the mixer drum, The mixer drum control device includes a controller that receives an operation signal including the target rotational speed of the mixer drum and outputs a command value corresponding to the target rotational speed of the engine or electric motor in response to the operation signal. The mixer drum control device is characterized in that, when the target rotational speed of the mixer drum is higher than the stirring rotational speed when stirring the contents loaded in the mixer drum, the controller outputs a correction command value that increases the torque of the engine or electric motor as the command value corresponding to the target rotational speed of the engine or electric motor.

2. A mixer drum control device according to claim 1, The system further includes a detector that detects information regarding the weight of the load and outputs it to the controller, The controller is a mixer drum control device characterized in that it outputs the correction command value when the target rotation speed of the mixer drum is higher than the stirring rotation speed and the detector detects a load of a predetermined level or higher.

3. A mixer drum control device according to claim 1, The controller has an acquisition unit that acquires property data of the loaded material, The controller is a mixer drum control device characterized in that it outputs the correction command value when the target rotation speed of the mixer drum is higher than the stirring rotation speed and the property data satisfies predetermined conditions.

4. A mixer drum control device according to claim 1, The controller is characterized in that, when the target rotation speed of the mixer drum exceeds a predetermined value, it outputs the command value instead of the correction command value.

5. A mixer drum control device according to any one of claims 1 to 4, The controller is characterized in that it outputs the correction command value when the target rotational speed of the mixer drum is higher than the stirring rotational speed and the rotational speed of the engine corresponding to the target rotational speed is 2000 rpm or less.

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