NZ757594A - Mixer drum washing apparatus - Google Patents

Abstract

The controller of the mixer drum washing apparatus controls the driving device so that the rotational speed of the mixer drum changes according to the target washing pattern in which the target rotational speed of the mixer drum at the time of washing is set. The target rotational speed of the mixer drum of the target washing pattern is set so as to increase to the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 at a predetermined time change rate, or to decrease from the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 at a predetermined time change rate. drum of the target washing pattern is set so as to increase to the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 at a predetermined time change rate, or to decrease from the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 at a predetermined time change rate.

Description

MIXER DRUM WASHING APPARATUS TECHNICAL FIELD The present invention relates to a mixer drum washing apparatus for a mixer vehicle.

BACKGROUND ART JP2002-67782A discloses a mixer drum washing apparatus for washing a mixer drum of a mixer vehicle. In this mixer drum washing apparatus, the inside of the mixer drum is washed by repeating the rotation in the charging direction and the rotation in the discharging direction.

SUMMARY OF INVENTION In the mixer drum washing apparatus described in JP2002-67782A, the rotational direction of the mixer drum is switched so as to rotate at a predetermined rotational speed in the discharging direction from a state in which the mixer drum is rotated at a predetermined rotational speed in the charging direction. When the rotational direction of the mixer drum is simply switched in this manner, the vehicle may vibrate largely due to the impact at the time of switching.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to suppress vibration of a vehicle which occurs when a mixer drum is washed.

The present invention is characterized in that a mixer drum washing apparatus includes: a mixer drum rotatably mounted on the vehicle; a driving device capable of rotationally driving the mixer drum in a charging direction and a discharging direction; and a controller that controls an operation of the driving device, when a washing instruction for the mixer drum is input, so as to alternately repeat a charging direction rotation in which the mixer drum rotates in the charging direction at a predetermined charging-side washing rotational speed and a discharging direction rotation in which the mixer drum rotates in the discharging direction at a predetermined discharging-side washing rotational speed. The controller has a target washing pattern in which a target rotational speed of the mixer drum at the time of washing is set, and controls the driving device so that a rotational speed of the mixer drum changes according to a target washing pattern. The target rotational speed of the mixer drum in the target washing pattern is set so as to increase to the charging-side washing rotational speed and the discharging-side washing rotational speed at a predetermined time change rate, or to decrease from the charging-side washing rotational speed and the discharging-side washing rotational speed at a predetermined time change rate.

According to the present invention, the rotational speed of the mixer drum at the time of washing the mixer drum is controlled so as to increase to the charging-side washing rotational speed and the discharging-side washing rotational speed at a predetermined time change rate, or to decrease from the charging-side washing rotational speed and the discharging-side washing rotational speed at a predetermined time change rate. Thus, at least before and after the switchover of the rotational direction of the mixer drum, the rotational speed of the mixer drum is controlled so as to gradually change with the passage of time and thereby sudden switchover of the rotational direction of the mixer drum is restrained.

The present invention is characterized in that the target rotational speed of the mixer drum in the target washing pattern is set so as to increase to the charging-side washing rotational speed and the discharging-side washing rotational speed at a predetermined first time change rate, and to decrease from the charging-side washing rotational speed and the discharging-side washing rotational speed at a predetermined second time change rate that is different from the first time change rate.

According to the present invention, the rotational speed of the mixer drum at the time of washing the mixer drum is controlled so as to increase to the charging-side washing rotational speed and the discharging-side washing rotational speed at the first time change rate, and to decrease from the charging-side washing rotational speed and the discharging-side washing rotational speed at the second time change rate that is different from the first time change rate. As described above, by making the time change rate different between the case where the rotational speed of the mixer drum increases to the charging-side washing rotational speed and the discharging-side washing rotational speed and the case where the rotational speed of the mixer drum decreases from the charging-side washing rotational speed and the discharging-side washing rotational speed, it is possible to achieve both the improvement of the washing power and the reduction of the impact at the time of switching the rotational direction of the mixer drum.

The present invention is characterized in that the first time change rate is larger than the second time change rate.

In the present invention, the first time change rate is set to be larger than the second time change rate. In this manner, the washing power can be improved by increasing the time change rate of the target rotational speed when the rotational speed of the mixer drum increases to the charging-side washing rotational speed and the discharging-side washing rotational speed, and by decreasing the time change rate of the target rotational speed when the rotational speed of the mixer drum decreases from the charging-side washing rotational speed and the discharging-side washing rotational speed, the impact at the time of switching the rotational direction of the mixer drum can be reduced.

The present invention is characterized in that the target washing pattern includes a start pattern in which a target rotational speed of the mixer drum after starting washing of the mixer drum until the rotational speed of the mixer drum reaches the charging-side washing rotational speed is set, and the target rotational speed of the mixer drum in the start pattern is set to increase at a predetermined third time change rate toward the charging-side washing rotational speed and further increase at a predetermined fourth time change rate which is different from the third time change rate before reaching the charging-side washing rotational speed.

In the present invention, the time change rate of the target rotational speed of the mixer drum is changed until the washing of the mixer drum is started and the rotational speed of the mixer drum reaches the charging-side washing rotational speed. As described above, by changing the time change rate, the rotational speed of the mixer drum can slowly reach the charging-side washing rotational speed, and as a result, the vibration of the vehicle which occurs when the rotational speed of the mixer drum reaches the charging-side washing rotational speed can be reduced.

The present invention is characterized in that the fourth time change rate is smaller than the third time change rate.

According to the present invention, the time change rate of the target rotational speed of the mixer drum before reaching the charging-side washing rotational speed is set small. In this manner, by reducing the time change rate of the target rotational speed of the mixer drum before reaching the charging-side washing rotational speed, the rotational speed of the mixer drum can slowly reach the charging-side washing rotational speed, and as a result, it is possible to reduce vibration of the vehicle which occurs when the rotational speed of the mixer drum reaches the charging-side washing rotational speed.

The invention is characterized in that the controller changes a time for rotating the mixer drum in the discharging direction according to the amount of washing fluid charged into the mixer drum.

In the present invention, the time to rotate the mixer drum in the discharging direction is changed in accordance with the amount of washing fluid charged into the mixer drum. In this manner, by changing the time for rotating the mixer drum in the discharging direction in accordance with the amount of the washing fluid charged into the mixer drum, it is possible to efficiently remove the deposits adhering to the vicinity of the opening while preventing the washing fluid from overflowing from the opening of the mixer drum.

The present invention is characterized in that the discharging-side washing rotational speed is set to be smaller than the charging-side washing rotational speed.

In the present invention, the discharging-side washing rotational speed is set to be smaller than the charging-side washing rotational speed. In this manner, by setting the discharging-side washing rotational speed to be smaller than the charging-side washing rotational speed, it is possible to prevent the washing fluid from overflowing from the opening of the mixer drum, and by providing a difference between the charging-side washing rotational speed and the discharging-side washing rotational speed, it is possible to make the flow of the washing fluid moving in the mixer drum slower or faster and to improve the washing power.

The present invention is characterized in that the controller rotates the mixer drum by repeatedly performing a plurality of cycles from the start of the charging direction rotation to the end of the discharging direction rotation as one cycle, and changes at least one of the charging-side washing rotational speed and the discharging-side washing rotational speed for each cycle.

In the present invention, at least one of the charging-side washing rotational speed and the discharging-side washing rotational speed is changed for each cycle. In this manner, by changing the charging-side washing rotational speed and the discharging-side washing rotational speed for each cycle, the flow of the washing fluid moving in the mixer drum can be made slower and faster, and the washing power can be improved.

BRIEF DESCRIPTION OF DRAWINGS is a side view of a mixer vehicle to which a mixer drum washing apparatus according to an embodiment of the present invention is applied; is a block diagram showing a hardware configuration of a mixer drum washing apparatus according to an embodiment of the present invention; is a diagram showing a washing pattern by a mixer drum washing apparatus according to an embodiment of the present invention; is an enlarged view showing a start part of a washing pattern by the mixer drum washing apparatus according to the embodiment of the present invention; is an enlarged view of a part of a washing pattern by the mixer drum washing apparatus according to the embodiment of the present invention; is a flow chart showing a processing procedure when washing the mixer drum in the mixer drum washing apparatus according to an embodiment of the present invention; and is a view showing a modification of the washing pattern by the mixer drum washing apparatus according to the embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

First, an overall configuration of a mixer vehicle 1 to which a mixer drum washing apparatus 100 according to an embodiment of the present invention is applied will be described with reference to FIGS. 1 and 2. is a schematic diagram showing a side surface of a mixer vehicle 1, and is a block diagram showing a hardware configuration of a mixer drum washing apparatus 100.

The mixer vehicle 1 is a vehicle for transporting so-called ready-mixed concrete such as mortar charged into the mixer drum 2.

In the following description, a case where the mixer vehicle 1 loads ready-mixed concrete as a load will be described.

As shown in the mixer vehicle 1 is a vehicle including a cab 11 and a frame 3, and includes a mixer drum 2 mounted on the frame 3 and capable of mounting a ready-mixed concrete, a driving device 4 for driving the mixer drum 2 to rotate, and a controller 20 for controlling the rotation of the mixer drum 2.

Mixer drum 2 is a bottomed cylindrical container mounted to rotate on the frame 3, an opening 2a to be used to charge and discharge the ready-mixed concrete is provided at the rear end. The mixer drum 2 is mounted so as to be inclined so that the rotational axis O thereof becomes gradually higher from the front portion toward the rear portion of the vehicle. In the mixer drum 2, a drum blade (not shown) is spirally disposed along the inner wall surface of the drum, and the drum blade rotates together with the mixer drum 2, thereby the ready-mixed concrete loaded in the mixer drum 2 is agitated or the like.

A hopper 16 is provided at a rear upper portion of the opening 2a of the mixer drum 2. The ready-mixed concrete charged into the mixer vehicle 1 in the 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 a rear lower portion 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 discharged in a predetermined direction by the chute 18.

The mixer drum 2 is rotationally driven via a driving device 4 using an engine 10 for driving as a power source mounted on the mixer vehicle 1. The driving device 4 is a hydraulic device that is driven by the rotation of the engine 10 and rotationally drives the mixer drum 2 by the fluid pressure of the working fluid.

As shown in the engine 10 has a throttle valve 10a for adjusting the output and the rotational speed of the engine 10. The opening degree of the throttle valve 10a is controlled by the controller via an actuator (not shown) when the driving device 4 is driven by the engine 10. Further, the engine 10 is provided with a rotation sensor 10b that detects the rotational speed of the engine 10 and outputs a signal corresponding to the detected rotational speed to the controller 20.

The rotational speed of the engine 10 when driving the driving device 4 is controlled by the controller 20 via the throttle valve 10a so that the rotational speed detected by the rotation sensor 10b becomes a predetermined speed. The rotation sensor 10b may detect the rotational speed of the PTO shaft 9 and the drive shaft 8, which are input shafts of the driving device 4.

Rotation of the engine 10 is transmitted to the driving device 4 via a PTO shaft 9 (PTO: Power take-off) which constantly extracts power from the engine 10, and a drive shaft 8 (see which connects the PTO shaft 9 and the driving device 4.

The driving device 4 includes a hydraulic pump 5 driven by an engine 10 to discharge hydraulic fluid as a working fluid, and a hydraulic motor 6 driven by hydraulic fluid supplied from the hydraulic pump 5 to drive the mixer drum 2 to rotate. In the driving device 4, other incompressible fluid may be used as the working fluid instead of the hydraulic fluid.

The hydraulic pump 5 is a swash plate type axial piston pump in which the discharge amount and the discharging direction are changed in accordance with the tilt angle of a swash plate (not shown), and includes a capacity detecting sensor 5a for detecting the discharge amount and the discharging direction of the hydraulic pump 5, and a solenoid valve 5b for adjusting the tilt angle of the swash plate. The capacity detecting sensor 5a outputs signals corresponding to the detected discharge amount to the controller 20.

The discharge quantity and the discharging direction of the hydraulic pump 5 are changed by switching the solenoid valve 5b by the controller 20. The hydraulic pump 5 may be a swash plate type axial piston pump in which the discharge amount is changed in accordance with the inclination angle of the swash plate and the discharging direction is changed by a discharging direction switching valve.

The hydraulic pump 5 is provided with a pressure sensor 5c for detecting the discharge pressure of the hydraulic pump 5. The pressure sensor 5c outputs signals corresponding to the detected pressure of the hydraulic fluid to the controller 20. The pressure sensor 5c may be provided in the hydraulic motor 6 to detect the pressure of the hydraulic fluid supplied from the hydraulic pump 5 to the hydraulic motor 6. In this manner, the pressure sensor 5c detects the pressure of the hydraulic fluid in the driving device 4.

The hydraulic motor 6 is a swash plate type axial piston motor whose displacement is changed in accordance with the inclination angle of a swash plate (not shown), and has a solenoid valve 6b for adjusting the inclination angle of the swash plate. By switching the solenoid valve 6b by the controller 20, the displacement of the hydraulic motor 6 is switched between two stages: a small displacement for high-speed rotation and a large displacement for normal rotation. The hydraulic motor 6 may be a swash plate type axial piston motor whose capacity can be continuously changed from a small capacity to a large capacity.

Further, the hydraulic motor 6 is provided with a rotation sensor 6a for detecting a rotational direction and a rotational speed of an output shaft (not shown) of the hydraulic motor 6. The rotation sensor 6a outputs signals corresponding to the detected rotational direction and rotational speed of the output shafts to the controller In the driving device 4 configured as described above, the hydraulic motor 6 is rotated by the hydraulic oil discharged from the hydraulic pump 5 being supplied to the hydraulic motor 6, and the rotational speed of the hydraulic motor 6 is changed in accordance with the amount of supplied oil and the inclination angle of the swash plate of the hydraulic motor 6. The rotational direction of the hydraulic motor 6 is switched by switching the discharging direction in the hydraulic pump 5.

The rotation of the hydraulic motor 6 of the driving device 4 is transmitted to the mixer drum 2 via the reduction gear 7, whereby the rotational direction of the mixer drum 2 can be switched between the charging direction, which is the normal rotational direction, and the discharging direction, which is the reverse rotational direction, and the rotational speed of the mixer drum 2 can be increased or decreased.

When the mixer drum 2 is rotationally driven in the charging direction, the ready-mixed concrete in the mixer drum 2 moves forward while being agitated by the drum blade. On the other hand, when the mixer drum 2 is rotationally driven in the discharging direction, the ready-mixed concrete in the mixer drum 2 moves backward while being agitated by the drum blade.

By rotating the mixer drum 2 in the discharging direction which is the opposite direction to the charging direction in this manner, 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 a flow guide 17 and a chute 18.

When the ready-mixed concrete is charged into the mixer drum 2 via the hopper 16, the mixer drum 2 is rotated at a higher speed than that at the time of stirring in the charging direction, so that the charged ready-mixed concrete is quickly moved to the front of the mixer drum 2.

In the driving device 4 having the above-described configuration, since the hydraulic pump 5 is driven to rotate by the power constantly extracted from the engine 10 via the PTO shaft 9, the rotational speed of the hydraulic pump 5 is affected by the change in the rotational speed of the engine 10 for driving according to the running state of the vehicle. Therefore, in the mixer vehicle 1, the rotational speed of the hydraulic motor 6 is controlled by the controller 20 so that the rotational speed of the mixer drum 2 becomes the target rotational speed. The drive source for rotationally driving the hydraulic pump 5 is not limited to the engine 10 for driving, and may be an auxiliary engine or an electric motor that is not used for running.

The controller 20 is composed of a microcomputer including 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. The RAM stores data in the processing of the CPU, the ROM stores a control program of the CPU and the like in advance, and the I/O interface is used for input/output of information to/from a connected device. The operation of the driving device 4 is controlled by operating the CPU, the RAM, and the like in accordance with a program stored in the ROM.

The controller 20 is disposed in the cab 11 together with the parking brake 31 and the operating device 32 for operating the mixer drum 2. In addition, the controller 20 is provided with a display unit 20a for displaying the state of the mixer drum 2 in the flashing state of the character code or the lamp, and the operator or the maintenance operator can confirm, for example, the kind of abnormal state in the control state of the mixer drum 2 by viewing the display of the display unit 20a.

The parking brake 31 is provided with a detector (not shown) for detecting the lever position of the parking brake 31. When the parking brake 31 is applied, a stop signal is output from the detector to the controller 20.

The operating device 32 is provided with a knob-type operating switch 32a for switching the rotational direction and the rotational speed of the mixer drum 2, an input unit 32b to which a washing setting to be described later is input by an operator, an emergency stop switch 32c for stopping the rotation of the mixer drum 2 in an emergency, and a washing switch 32d for automatically washing and rotating the mixer drum 2. In order to enable the mixer drum 2 to be operated outside the mixer vehicle 1, an operating device similar to the operating device 32 may be disposed at the rear portion of the mixer vehicle 1. When the operating device 32 is installed in a place easier to see than the controller 20, the display unit 20a may be provided on the operating device 32.

When the operator operates the operating switch 32a, the controller 20 sets a target rotation state such as the rotational direction and the target rotational speed of the mixer drum 2 in accordance with the operation direction and the operation amount of the operating switch 32a, and controls the driving device 4 and the engine 10 so that the rotation state of the mixer drum 2 becomes the target rotation state.

Specifically, since the rotation state of the mixer drum 2 correlates with the rotation state of the hydraulic motor 6, the controller 20 switches the discharging direction of the hydraulic pump via the solenoid valve 5b so that the rotational direction signals of the hydraulic motor 6 inputted through the rotation sensor 6a become the desired rotational direction. In addition, the controller 20 appropriately changes the discharge amount of the hydraulic pump 5 via the solenoid valve 5b and appropriately changes the displacement of the hydraulic motor 6 via the solenoid valve 6b so that the rotational speed signal of the hydraulic motor 6 inputted via the rotation sensor 6a becomes a desired magnitude.

When the emergency stop switch 32c is operated by the operator, the controller 20 controls the driving device 4 to stop the rotation of the mixer drum 2.

Further, when the washing switch 32d is operated by the operator, the controller 20 controls the driving device 4 so as to alternately repeat the charging direction rotation for rotating the mixer drum 2 in the charging direction at a predetermined charging-side washing rotational speed DN1 and the discharging direction rotation for rotating the mixer drum 2 in the discharging direction at a predetermined discharging-side washing rotational speed DN2. As described above, when the operator operates the washing switch 32d, the mixer drum washing apparatus 100 performs washing of the mixer drum 2.

Hereinafter, the washing of the mixer drum 2 by the mixer drum washing apparatus 100 will be described in detail with reference to FIGS. 2 to 6. is a block diagram showing a hardware configuration of the mixer drum washing apparatus 100, FIGS. 3 to 5 are diagrams showing a washing pattern by the mixer drum washing apparatus 100, and is a flowchart showing a processing procedure when the mixer drum 2 is washed in the mixer drum washing apparatus 100.

As shown in the mixer drum washing apparatus 100 for washing mixer drum 2 is mainly composed of a mixer drum 2 rotatably mounted on the vehicle, a driving device 4 capable of rotationally driving the mixer drum 2 in the charging direction and the discharging direction, and controller 20 that controls the operation of the driving device 4, when an instruction to wash the mixer drum 2 is input, so as to alternately repeat the charging direction rotation in which the mixer drum 2 rotates in the charging direction and the discharging direction rotation in which the mixer drum 2 rotates in the discharging direction. The description of each configuration is omitted because it has been described above.

The ROM of the controller 20 stores a target washing pattern in which a target change of the rotational speed of the mixer drum 2 at the time of washing the mixer drum 2 is set, as shown in in order to perform washing of the mixer drum 2. The ROM of the controller 20 stores a target change of the rotational speed of the engine 10 when the mixer drum 2 is washed in accordance with the target washing pattern as shown in The target washing pattern is composed of three patterns: a start pattern PS in which a target transition of the rotational speed of the mixer drum 2 at the time of starting washing is set; a washing pattern PW in which a target transition of the rotational speed of the mixer drum 2 at the time of washing is set; and an end pattern PE in which a target transition of the rotational speed of the mixer drum 2 at the time of finishing washing is set.

The washing pattern PW is a combination of a charging direction rotation pattern 41 for rotating the mixer drum 2 in the charging direction and a discharging direction rotation pattern 42 for rotating the mixer drum 2 in the output direction.

The charging direction rotation pattern 41 is a process of vigorously moving water input into the mixer drum 2 as a washing fluid toward the front of the mixer drum 2. The charging direction rotation pattern 41 includes the charge increasing section 41a in which the rotational speed increases toward the charging-side washing rotational speed DN1, the charge constant section 41b in which the rotational speed becomes the charging-side washing rotational speed DN1, and the charge decreasing section 41c in which the rotational speed decreases from the charging-side washing rotational speed DN1.

The discharging direction rotation pattern 42 is a process of vigorously transferring the water charged into the mixer drum 2 toward the opening 2a of the mixer drum 2. The discharging direction rotation pattern 42 includes the discharge increasing section 42a in which the rotational speed increases toward the discharging-side washing rotational speed DN2, the discharge constant section 42b in which the rotational speed becomes the discharging-side washing rotational speed DN2, and the discharge decreasing section 42c in which the rotational speed decreases from the discharging-side washing rotational speed DN2. The charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 may be set to the same rotational speed or may be different rotational speed.

The start pattern PS is substantially the same as the combination of the charging direction rotation pattern 41 and the discharging direction rotation pattern 42 of the washing pattern PW, and the end pattern PE is the same as the charging direction rotation pattern 41 of the washing pattern PW.

In accordance with the target washing pattern set in this manner, the mixer drum 2 into which the water as the washing fluid is input is repeatedly rotated in the charging direction and the discharging direction, whereby the inside of the mixer drum 2 is washed, and the water in the mixer drum 2 is collected in front of the mixer drum 2 in the end pattern PE.

Here, if the target rotational speed is set to shift from the charging-side washing rotational speed DN1 to zero rotation in the charge decreasing section 41c of the charging direction rotation pattern 41 without decreasing the target rotational speed at a predetermined time change rate, and the target rotational speed is set to shift from zero rotation to the discharging-side washing rotational speed DN2 in the discharge increasing section 42a of the discharging direction rotation pattern 42 without increasing the target rotational speed at a predetermined time change rate, the rotational direction of the mixer drum 2 changes suddenly.

When the rotational direction of the mixer drum 2 is rapidly changed in this manner, the vehicle may swing largely due to the impact. If the vehicle vibrates largely while the mixer drum 2 is washed in this manner, the operator may feel danger, or may be misunderstood or anxious that some trouble occurs in the mixer drum washing apparatus 100.

This is the same when the target rotational speed is set to shift from the discharging-side washing rotational speed DN2 to zero rotation in the discharge decreasing section 42c of the discharging direction rotation pattern 42, and the target rotational speed is set to shift from zero rotation to the charging-side washing rotational speed DN1 in the charge increasing section 41a of the charging direction rotation pattern 41.

In the present embodiment, in order to suppress the large vibration of the vehicle when washing the mixer drum 2, the target rotational speed of the mixer drum 2 in the charge increasing section 41a and the discharge increasing section 42a is gradually increased at the first time change rate, which is a predetermined time change rate, and the target rotational speed of the mixer drum 2 in the charge decreasing section 41c and the discharge decreasing section 42c is gradually decreased at the second time change rate, which is a predetermined time change rate.

If the target rotational speed of the mixer drum 2 in the charge increasing section 41a, the charge decreasing section 41c, the discharge increasing section 42a, and the discharge decreasing section 42c is gradually changed with the elapse of time, it takes time when the rotational direction of the mixer drum 2 is switched, as compared with the case where the target rotational speed is instantaneously changed, so that the rotational direction of the mixer drum 2 is naturally slowly switched. As a result, it is possible to suppress the vehicle from vibrating due to the impact caused by the switching of the rotational direction of the mixer drum 2.

Although the first time change rate of the target rotational speed in the charge increasing section 41a and the second time change rate of the target rotational speed in the charge decreasing section 41c may be the same, the first time change rate in the charge increasing section 41a is set to be larger than the second time change rate in the charge decreasing section 41c because it is preferable to shorten the time until reaching the charging-side washing rotational speed DN1 in order to encourage the flow of water in the mixer drum 2 and improve the washing power. For the same reason, the first time change rate of the target rotational speed in the discharge increasing section 42a is set to be larger than the second time change rate of the target rotational speed in the discharge decreasing section 42c.

Also, when washing of the mixer drum 2 is started, as shown in the rotational speed of the engine 10 also increases at the same time as the rotational speed of the mixer drum 2, and it becomes the washing rotational speed EN1 that is a predetermined rotational speed from the idling state. As described above, when the increase in the rotational speed of the engine 10 and the increase in the rotational speed of the mixer drum 2 overlap, the vibration of the vehicle caused by the rotational speed of the engine 10 reaching the washing rotational speed EN1 and the vibration of the vehicle caused by the rotational speed of the mixer drum 2 reaching the charging-side washing rotational speed DN1 are superimposed, and as a result, the vehicle may swing greatly.

In the present embodiment, the start pattern PS is set as follows in order to suppress a large vibration of the vehicle when the washing of the mixer drum 2 is started.

As shown in an enlarged view in the start pattern PS has a first start pattern 43 for rotating the mixer drum 2 in the charging direction together with the start of washing, and a second start pattern 44 for rotating the mixer drum 2 in the discharging direction following the first start pattern 43. The second start pattern 44 is set in the same manner as the discharging direction rotation pattern 42 of the washing pattern PW, and therefore the description thereof is omitted.

The first start pattern 43 is a step of vigorously moving the water charged into the mixer drum 2 as the washing fluid toward the front of the mixer drum 2, similarly to the charging direction rotation pattern 41 of the washing pattern PW.

The first start pattern 43 has a first charge increasing section 43a in which the rotational speed increases from zero rotation to the charging-side washing rotational speed DN1, a second charge increasing section 43b in which the rotational speed is switched from the first charge increasing section 43a prior to reaching the charging-side washing rotational speed DN1, and an charge decreasing section 43c in which the rotational speed decreases from the charging-side washing rotational speed DN1.

The fourth time change rate, which is a predetermined time change rate of the target rotational speed in the second charge increasing section 43b, is set to be smaller than the third time change rate, which is a predetermined time change rate of the target rotational speed in the first charge increasing section 43a. The time change rate of the target rotational speed in the charge decreasing section 43c is the same as the time change rate of the charge decreasing section 41c of the charging direction rotation pattern 41.

In this way, the fourth time change rate in the second charge increasing section 43b is reduced, and before the rotational speed of the mixer drum 2 reaches the charging-side washing rotational speed DN1, the degree of increase in the rotational speed of the mixer drum 2 is made gentle, whereby the rotational speed of the mixer drum 2 is prevented from overshooting, and the vibrations of the vehicles generated when the rotational speed of the mixer drum 2 reaches the charging-side washing rotational speed DN1 can be reduced.

As a result, even if an overshoot occurs and the vehicle vibrates when the rotational speed of the engine 10 reaches the rotational speed EN1 at the time of washing, the vibration of the vehicle caused by the rotational speed of the mixer drum 2 reaching the charging-side washing rotational speed DN1 is suppressed, so that the vehicle is prevented from swinging greatly.

As shown in the timing at which the rotational speed of the mixer drum 2 reaches the charging-side washing rotational speed DN1 in the first start pattern 43 is set to be later than the timing at which the rotational speed of the engine 10 reaches the washing rotational speed EN1.

By setting the first start pattern 43 in this manner, even if the vehicle slightly vibrates by the rotational speed of the mixer drum 2 reaching the charging-side washing rotational speed DN1, the vehicle is restrained from swinging largely because the timing at which the vibration occurs deviates from the timing at which the vibration occurs due to the rotational speed of the engine 10 reaching the washing rotational speed EN1.

In the first start pattern 43, the charge increasing section is configured by two sections, but the charge increasing section may be configured by three or more sections, and the rotational speed of the mixer drum 2 may more slowly reach the charging-side washing rotational speed DN1. Further, not only at the time of starting the washing of the mixer drum 2, but also the charge increasing section 41a and the discharge increasing section 42a of the washing pattern PW may be configured by a plurality of sections in the same manner as the first start pattern 43, so that the rotational speed of the mixer drum 2 slowly reaches the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2.

In addition, in washing the mixer drum 2 by the mixer drum washing apparatus 100, since the ready-mixed concrete adheres to the vicinity of the opening 2a in particular in the mixer drum 2 after the ready-mixed concrete has been discharged, it is preferable to prolong the time of the discharging direction rotation pattern 42 in the pattern during washing pattern PW, in particular, the time of the discharge constant section 42b, and actively guide the water to the vicinity of the opening 2a.

However, when the quantity of water charged into the mixer drum 2 for washing is large, if the discharge constant section 42b is lengthened, the water overflows from the opening 2a. On the other hand, if the time of the discharge constant section 42b is limited to prevent water from overflowing from the opening 2a, when the amount of water charged into the mixer drum 2 is small, water is not guided to the vicinity of the opening 2a, and as a result, it becomes difficult to remove the ready-mixed concrete adhering to the vicinity of the opening 2a.

In order to prevent the overflow of water from the opening 2a or the inability to guide the water to the vicinity of the opening 2a depending on the amount of the water charged into the mixer drum 2, in the present embodiment, the time of the discharging direction rotation pattern 42 in the washing pattern PW, in particular, the time of the discharge constant section 42b is changed in accordance with the amount of the water charged into the mixer drum 2.

More specifically, as shown in when the amount of water charged into the mixer drum 2 is small, the washing pattern PW is changed to a pattern indicated by a solid line in which the time of the discharge constant section 42b is the first time T1, while when the amount of water charged into the mixer drum 2 is large, the washing pattern PW is changed to a pattern indicated by a broken line in which the time of the discharge constant section 42b is the second time T2 shorter than the first time T1.

When the quantity of the water charged into the mixer drum 2 is small as described above, the time of the discharging direction rotation pattern 42, particularly the time of the discharge constant section 42b, is lengthened, so that the ready-mixed concrete adhering to the vicinity of the opening 2a of the mixer drum 2 can be efficiently removed with little water even in the area where the water is valuable.

Further, when the quantity of the water charged into the mixer drum 2 is large, by shortening the time of the discharging direction rotation pattern 42, particularly the time of the discharge constant section 42b, it is possible to efficiently remove the ready-mixed concrete adhering to the vicinity of the opening 2a while preventing the water from overflowing from the opening 2a of the mixer drum 2.

The relationship between the amount of water charged into the mixer drum 2 and the time of the discharge constant section 42b is stored in advance in the ROM as a map.

Instead of changing the time of the discharge constant section 42b in accordance with the amount of water charged into the mixer drum 2, the rotational speed of the mixer drum 2 in the discharge constant section 42b may be changed. In this case, when the amount of water is small, the centrifugal force is increased by making a relatively high rotational speed to guide water to the vicinity of the opening 2a of the mixer drum 2, and when the amount of water is large, the centrifugal force is decreased by making a relatively low rotational speed to prevent water from overflowing from the opening 2a of the mixer drum 2.

Next, with reference to the flowchart of a processing procedure when the mixer drum 2 is washed by the mixer drum washing apparatus 100 will be described.

First, in step S101, it is determined whether or not the operator presses the washing switch 32d of the operating device 32.

When the washing switch 32d is not pressed, the process is once finished, and when the washing switch 32d is pressed, the process proceeds to step S102.

In step S102, it is determined whether or not the washing setting has already been performed. The washing setting means the number of times through executed cycle when one cycle is defined from the start of the charging direction rotation pattern 41 to the end of the discharging direction rotation pattern 42, and the amount of water are charged into the mixer drum 2. In addition, the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2, the lengths of the sections 41a to 41c and 42a to 42c, and the time change rate may be set.

If the washing setting has already been performed, the process proceeds to step S104, and if the washing setting has not yet been performed, the process proceeds to step S103.

In step S103, the operator inputs the washing setting such as the quantity of water charged into the mixer drum 2 via the input unit 32b of the operating device 32, the washing pattern, and the number of repetitions of the washing pattern. When the inputting of the washing setting is completed, the process proceeds to step S104.

When the input is completed, it is possible to omit the input of the washing setting from the next time by selecting to perform the washing with the same setting in the future.

In the following step S104, it is determined whether or not there is an abnormality in the entire system of the mixer vehicle 1. If there is any abnormality, the process proceeds to step S109 without washing the mixer drum 2 for safety, and the reason why the washing cannot be performed, specifically where the abnormality exists, is displayed on the display unit 20a, and the process is temporarily terminated. If there are no abnormalities, the process proceeds to step S105.

In step S105, it is determined whether or not the mixer drum 2 is stopped. When the mixer drum 2 is rotating, there is a possibility that ready-mixed concrete is still loaded in the mixer drum 2, and therefore, the process proceeds to step S109 without performing washing of the mixer drum 2 for safety, and a message indicating that washing is not possible because the mixer drum 2 is rotating is displayed on the display unit 20a, and the process is once terminated. When the mixer drum 2 is stopped, the process proceeds to step S106.

In step S106, it is determined whether or not the parking brake 31 is being applied. When the parking brake 31 is not applied, the vehicle may move while the mixer drum 2 is being washed, and therefore, the process proceeds to step S109 without washing the mixer drum 2 for safety, and a message indicating that the vehicle cannot be washed because the parking brake 31 is not applied is displayed on the display unit 20a, and the process is temporarily terminated. When the parking brake 31 is applied, the process proceeds to step S107.

In step S107, it is determined whether or not ready-mixed concrete is loaded in the mixer drum 2. More specifically, the determination is made based on the detected values detected by the pressure sensor 5c when the mixer drum 2 is slightly rotated. When ready-mixed concrete is loaded in the mixer drum 2, the load for rotating the mixer drum 2 is larger than that in the case where water for washing is put in the mixer drum 2, and load fluctuation occurs when the ready-mixed concrete slides in the mixer drum 2. Therefore, when the detected value detected by the pressure sensor 5c is larger than a predetermined value, or when the variation range of the detected value is larger than a predetermined value, it can be determined that ready-mixed concrete is loaded in the mixer drum 2.

When it is determined that the ready-mixed concrete is loaded in the mixer drum 2, the mixer drum 2 cannot be washed, so that the process proceeds to step S109, the fact that the ready-mixed concrete is loaded in the mixer drum 2 is displayed on the display unit 20a, and the process is once terminated. When it is determined that the ready-mixed concrete is not loaded in the mixer drum 2, the process proceeds to step S108.

In step S108, the mixer drum 2 starts to be washed.

Specifically, the controller 20 controls the operation of the driving device 4 and the rotational speed of the engine 10 so that the mixer drum 2 rotates in accordance with the above-mentioned target washing pattern.

In step S108, when the washing of the mixer drum 2 is started, the process proceeds to step S110, and it is determined whether or not the washing switch 32d of the operating device 32 is pressed again by the operator. When any switch or the like is operated after the washing of the mixer drum 2 is started, it is considered that there is an intention to suspend or stop the washing of the mixer drum 2, and therefore, when the washing switch 32d is pressed again, the process proceeds to step S111 and the washing of the mixer drum 2 is forcibly terminated. Then, since the washing switch 32d is pressed, the fact that the washing is forcibly terminated is displayed on the display unit 20a, and the processing is terminated.

If the washing switch 32d is not pressed again in step S110, the process proceeds to step S112, and it is determined whether or not the operator has operated the operating device 32. When some operation is performed via the operating device 32 after the washing of the mixer drum 2 is started, it is considered that there is an intention to suspend or stop the washing of the mixer drum 2, and therefore, when the operating device 32 is operated, the process proceeds to step S111 and the washing of the mixer drum 2 is forcibly terminated.

Then, since the operating device 32 has been operated, the fact that the washing has been forcibly terminated is displayed on the display unit 20a, and the processing is terminated.

In step S112, when the operating device 32 is not operated, the process proceeds to step S113, and it is determined whether or not the emergency stop switch 32c is pressed by the operator. When the emergency stop switch 32c is pressed, the process proceeds to step S111, and the washing of the mixer drum 2 is forcibly terminated.

Then, since the emergency stop switch 32c is pressed, the fact that the washing is forcibly terminated is displayed on the display unit 20a, and the process is terminated. When the emergency stop switch 32c is not pressed, the process proceeds to step S114.

In step S114, it is determined whether or not the set number of cycles has been completed. If the set number of cycles has not yet been reached, the process returns to step S110, and the mixer drum 2 is continuously washed. When the number of cycles reaches the set number, the process proceeds to step S115, the fact that the washing of the mixer drum 2 has been normally completed is displayed on the display unit 20a, and the process is terminated.

In this manner, by rotating the mixer drum 2 in accordance with the above-mentioned target washing pattern, the mixer drum 2 can be washed while suppressing vibration of the vehicle.

According to the above embodiment, the following effects are obtained.

In the mixer drum washing apparatus 100, the target rotational speed of the mixer drum 2 in the charge increasing section 41a and the discharge increasing section 42a is gradually increased at a predetermined first time change rate, and the target rotational speed of the mixer drum 2 in the charge decreasing section 41c and the discharge decreasing section 42c is gradually decreased at a predetermined second time change rate.

By setting the target rotational speed of the mixer drum 2 in the charge increasing section 41a, the charge decreasing section 41c, the discharge increasing section 42a, and the discharge decreasing section 42c so as to gradually change with the passage of time, the rotational speed of the mixer drum 2 is controlled so as to gradually change with the passage of time before and after the rotational direction of the mixer drum 2 is switched. As a result, when the mixer drum 2 is washed, the rotational direction of the mixer drum 2 is restrained from being suddenly switched, and as a result, it is possible to restrain the vehicle from being vibrated by the impact caused by the switching of the rotational direction of the mixer drum Hereinafter, a modification of the embodiment of the present invention will be described.

In the above embodiment, as shown in the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 are the same in the respective cycles.

Alternatively, as shown in the charging-side washing rotational speed and the discharging-side washing rotational speed may be changed for each cycle. Specifically, the rotational speed of the charge constant section 41b is switched to the first charging-side washing rotational speed DN3 having a relatively high rotational speed and the second charging-side washing rotational speed DN5 having a relatively low rotational speed for each cycle, and the rotational speed of the discharge constant section 42b is switched to the first discharging-side washing rotational speed DN4 having a relatively high rotational speed and the second discharging-side washing rotational speed DN6 having a relatively low rotational speed for each cycle.

By switching the washing rotational speed per cycle in this manner, the flow of the water moving in the mixer drum 2 can be made slow and fast, and as a result, the wash power can be improved.

In the above embodiment, the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 are set to the same rotational speed. Alternatively, the discharging-side washing rotational speed DN2 may be set to a rotational speed lower than the charging-side washing rotational speed DN1. In this manner, by setting the discharging-side washing rotational speed DN2 to a relatively low rotational speed, it is possible to reliably prevent water from overflowing from the opening 2a of the mixer drum 2, and by setting a difference between the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2, the flow of water moving in the mixer drum 2 can be made slow and fast, and as a result, it is possible to improve the washing power.

In the above embodiment, the target rotational speed of the mixer drum 2 in the charge increasing section 41a and the discharge increasing section 42a changes linearly at a constant time change rate.

Alternatively, the time change rate of the target rotational speed of the mixer drum 2 in the charge increasing section 41a and the discharge increasing section 42a may be changed stepwise or continuously, for example, may be changed so as to gradually decrease as the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 are approached. In addition, the time change rate of the target rotational speed of the mixer drum 2 in the charge decreasing section 41c and the discharge decreasing section 42c may also be changed stepwise or continuously.

In the washing pattern PW in the above embodiment, the charging direction rotation pattern 41 and the discharging direction rotation pattern 42 are alternately repeated. Alternatively, the washing pattern PW may alternately repeat the charging direction rotation pattern 41 and the stop state, may alternately repeat the discharging direction rotation pattern 42 and the stop state, or may be a combination thereof. Further, the start pattern PS may also be temporarily stopped after being rotated in the charging direction, or may be temporarily stopped after being rotated in the discharging direction. The end pattern PE is not limited to the same as the charging direction rotation pattern 41, and may be the same as the discharging direction rotation pattern 42.

Further, in the above embodiment, information on the end of the washing of the mixer drum 2 is displayed on the display unit 20a.

Alternatively, a monitor capable of displaying information on the washing process and the washing setting of the mixer drum 2 by characters or images may be provided on the operating device 32 together with the input unit 32b.

Hereinafter, configurations, functions, and effects of the embodiments of the present invention will be collectively described.

The mixer drum washing apparatus 100 includes: a mixer drum 2 rotatably mounted on the vehicle; a driving device 4 capable of rotationally driving the mixer drum 2 in the charging direction and the discharging direction; and a controller 20 that controls the operation of the driving device 4, when a washing instruction for the mixer drum 2 is input, so as to alternately repeat the charging direction rotation in which the mixer drum 2 rotates in the charging direction at a predetermined charging-side washing rotational speed DN1 and the discharging direction rotation in which the mixer drum 2 rotates in the discharging direction at a predetermined discharging-side washing rotational speed DN2. The controller 20 has a target washing pattern in which the target rotational speed of the mixer drum 2 at the time of washing is set, and controls the driving device 4 so that the rotational speed of the mixer drum 2 changes according to the target washing pattern. The target rotational speed of the mixer drum 2 in the target washing pattern is set so as to increase to the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 at a predetermined time change rate, or to decrease from the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 at a predetermined time change rate.

In this configuration, the rotational speed of the mixer drum 2 at the time of washing the mixer drum 2 is controlled so as to increase to the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 at a predetermined time change rate, or to decrease from the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 at a predetermined time change rate. Thus, at least before and after the switchover of the rotational direction of the mixer drum 2, the rotational speed of the mixer drum 2 is controlled so as to gradually change with the passage of time and thereby sudden switchover of the rotational direction of the mixer drum 2 is restrained.

As a result, it is possible to suppress the vehicle from vibrating due to the impact caused by the switching of the rotational direction of the mixer drum 2.

In addition, the target rotational speed of the mixer drum 2 in the target washing pattern is set so as to increase to the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 at a predetermined first time change rate, and to decrease from the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 at a predetermined second time change rate that is different from the first time change rate.

If the time change rate of the rotational speed of the mixer drum 2 is increased, the flow of the water moving in the mixer drum 2 becomes vigorous and the washing power can be improved, while if the time change rate is decreased, the impact at the time of switching of the rotational direction of the mixer drum 2 can be alleviated. In this configuration, the rotational speed of the mixer drum 2 at the time of washing the mixer drum 2 is controlled so as to increase to the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 at the first time change rate, and to decrease from the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 at the second time change rate that is different from the first time change rate. As described above, by making the time change rate different between the case where the rotational speed of the mixer drum 2 increase to the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 and the case where the rotational speed of the mixer drum decreases from the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2, it is possible to achieve both improvement of the washing power and the reduction of the impact at the time of switching the rotational direction of the mixer drum 2.

The first time change rate is set to be larger than the second time change rate.

In this configuration, the time change rate of the target rotational speed when the rotational speed of the mixer drum 2 is increased to the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 is set to be larger than the time change rate of the target rotational speed when the rotational speed of the mixer drum 2 is decreased from the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2. In this manner, by increasing the time change rate of the target rotational speed when the rotational speed of the mixer drum 2 increases to the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2, the flow of water moving in the mixer drum 2 is forced to improve the washing power, and by reducing the time change rate of the target rotational speed when the rotational speed of the mixer drum 2 decreases from the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2, the impact at the time of switching the rotational direction of the mixer drum 2 can be reduced.

In addition, the target washing pattern includes a start pattern in which the target rotational speed of the mixer drum 2 after starting washing of the mixer drum 2 until the rotational speed of the mixer drum reaches the charging-side washing rotational speed DN1 is set, and the target rotational speed of the mixer drum 2 in the start pattern is set to increase at a predetermined third time change rate toward the charging-side washing rotational speed DN1 and further increase at a predetermined fourth time change rate which is different from the third time change rate before reaching the charging-side washing rotational speed DN1.

In this configuration, the time change rate of the rotational speed of the mixer drum 2 is changed until the washing of the mixer drum 2 is started and the rotational speed of the mixer drum 2 reaches the charging-side washing rotational speed DN1. As described above, by changing the time change rate, the rotational speed of the mixer drum 2 can slowly reach the charging-side washing rotational speed DN1, and as a result, the vibration of the vehicle which occurs when the rotational speed of the mixer drum 2 reaches the charging-side washing rotational speed DN1 can be reduced.

The fourth time change rate is set to be smaller than the third time change rate.

In this configuration, the time change rate of the target rotational speed of the mixer drum 2 before reaching the charging-side washing rotational speed DN1 is set small. In this manner, by reducing the time change rate of the target rotational speed of the mixer drum 2 before reaching the charging-side washing rotational speed DN1, the rotational speed of the mixer drum 2 can slowly reach the charging-side washing rotational speed DN1, and as a result, it is possible to reduce vibration of the vehicle which occurs when the rotational speed of the mixer drum 2 reaches the charging-side washing rotational speed DN1.

In addition, the controller 20 changes the time for rotating the mixer drum 2 in the discharging direction according to the amount of water charged into the mixer drum 2.

In this configuration, the time to rotate the mixer drum 2 in the discharging direction is changed in accordance with the amount of water charged into the mixer drum 2. In this manner, by changing the time for rotating the mixer drum 2 in the discharging direction in accordance with the amount of water charged into the mixer drum 2, it is possible to efficiently remove the ready-mixed concrete adhering to the vicinity of the opening 2a while preventing water from overflowing from the opening 2a of the mixer drum 2.

Further, the discharging-side washing rotational speed DN2 is set to be smaller than the charging-side washing rotational speed DN1.

In this configuration, the discharging-side washing rotational speed DN2 is set to be smaller than the charging-side washing rotational speed DN1. In this manner, by setting the discharging-side washing rotational speed DN2 to be smaller than the charging-side washing rotational speed DN1, it is possible to reliably prevent water from overflowing from the opening 2a of the mixer drum 2, and by providing a difference between the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2, it is possible to make the flow of water moving in the mixer drum 2 slower or faster and to improve the washing power.

Further, the controller 20 rotates the mixer drum 2 by repeatedly performing a plurality of cycles from the start of the charging direction rotation to the end of the discharging direction rotation as one cycle, and changes at least one of the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 for each cycle.

In this configuration, at least one of the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 is changed for each cycle. In this manner, by changing the charging-side washing rotational speed DN1 and the discharging-side washing rotational speed DN2 for each cycle, the flow of water moving in the mixer drum 2 can be made slow and faster, and the washing power can be improved.

The embodiments of the present invention described above are merely illustration of some application examples of the present invention and not of the nature to limit the technical scope of the present invention to the specific constructions of the above embodiments.

Claims (8)

WHAT IS CLAIMED IS:

1. A mixer drum washing apparatus, comprising: a mixer drum rotatably mounted on a vehicle; a driving device capable of rotationally driving the mixer drum in a charging direction and a discharging direction; and a controller configured to control an operation of the driving device, when an instruction to wash the mixer drum is input, so as to alternately repeat a charging direction rotation in which the mixer drum rotates in the charging direction at a predetermined charging-side washing rotational speed and a discharging direction rotation in which the mixer drum rotates in the discharging direction at a predetermined discharging-side washing rotational speed; wherein the controller has a target washing pattern in which a target rotational speed of the mixer drum at the time of washing is set, and controls the driving device so that a rotational speed of the mixer drum changes according to the target washing pattern, and the target rotational speed of the mixer drum in the target washing pattern is set so as to increase to the charging-side washing rotational speed and the discharging-side washing rotational speed at a predetermined time change rate, or to decrease from the charging-side washing rotational speed and the discharging-side washing rotational speed at a predetermined time change rate.

2. The mixer drum washing apparatus according to claim 1, wherein the target rotational speed of the mixer drum in the target washing pattern is set so as to increase to the charging-side washing rotational speed and the discharging-side washing rotational speed at a predetermined first time change rate, and to decrease from the charging-side washing rotational speed and the discharging-side washing rotational speed at a predetermined second time change rate that is different from the first time change rate.

3. The mixer drum washing apparatus according to claim 2, wherein the first time change rate is larger than the second time change rate.

4. The mixer drum washing apparatus according to any one of claims 1 to 3, wherein the target washing pattern includes a start pattern in which the target rotational speed of the mixer drum after starting washing of the mixer drum until the rotational speed of the mixer drum reaches the charging-side washing rotational speed is set, and the target rotational speed of the mixer drum in the start pattern is set to increase at a predetermined third time change rate toward the charging-side washing rotational speed and further increase at a predetermined fourth time change rate which is different from the third time change rate before reaching the charging-side washing rotational speed.

5. The mixer drum washing apparatus according to claim 4, wherein the fourth time change rate is smaller than the third time change rate.

6. The mixer drum washing apparatus according to any one of claims 1 to 5, wherein the controller changes a time for rotating the mixer drum in the discharging direction according to the amount of washing fluid charged into the mixer drum.

7. The mixer drum washing apparatus according to any one of claims 1 to 6, wherein the discharging-side washing rotational speed is set to be smaller than the charging-side washing rotational speed.

8. The mixer drum washing apparatus according to any one of claims 1 to 7, wherein the controller rotates the mixer drum by repeatedly performing a plurality of cycles from the start of the charging direction rotation to the end of the discharging direction rotation as one cycle, and changes at least one of the charging-side washing rotational speed and the discharging-side washing rotational speed for each cycle.