AU2016378702B2

AU2016378702B2 - Mixer drum driving apparatus

Info

Publication number: AU2016378702B2
Application number: AU2016378702A
Authority: AU
Inventors: Masaya Abe; Kazumi Ito
Original assignee: KYB Corp
Current assignee: KYB Corp
Priority date: 2015-12-24
Filing date: 2016-12-09
Publication date: 2019-03-28
Anticipated expiration: 2036-12-09
Also published as: WO2017110525A1; JP2017114288A; CN108430828B; CN108430828A; NZ743898A; AU2016378702A1; JP6335870B2

Abstract

A mixer drum drive device (100) is provided with: a hydraulic pump (5) driven by a propulsion engine (3) of a vehicle (1); a hydraulic motor (6) that drives a mixer drum (2) to rotate through the action of a working fluid discharged from the hydraulic pump (5); a control valve (8) that controls the flow of the working fluid from the hydraulic pump (5) to the hydraulic motor (6); an electric motor (11) that rotates due to electrical power during idling stop of the propulsion engine (3); an auxiliary hydraulic pump (12) that is driven by the rotation of the electric motor (11) to discharge the working fluid and operate the hydraulic motor (6); and a check valve (14) that prevents backflow of the working fluid from the control valve (8) toward the hydraulic pump (5).

Description

MIXER DRUM DRIVING APPARATUS

TECHNICAL FIELD [0001] The present invention relates to a mixer drum driving apparatus.

BACKGROUND ART [0002] A JP2012-91729A describes a drum rotating apparatus configured to rotate/drive a drum mounted rotatably on a mixer vehicle. The drum rotating apparatus described in JP2012-91729A includes a hydraulic pump driven by a running engine of the mixer vehicle, a hydraulic motor rotated by a pressure oil fed from the hydraulic pump, and a drum connected to an output shaft of the hydraulic motor. In the drum rotating apparatus described in JP2012-91729A, when a position of a switching valve is switched by an operation of a switching lever, a rotating direction of the hydraulic motor is switched to a normal direction or an opposite direction.

[0003] JP2014-196094A describes a driving apparatus configured to rotate / drive the mixer drum mounted on a vehicle and capable of loading a ready-mixed concrete. The driving apparatus described in JP2014-196094A includes a hydraulic pump driven by a running engine, a hydraulic motor operated by a working oil discharged from the hydraulic pump and configured to rotate/ drive the mixer drum, and a switching valve configured to switch a rotating direction of the hydraulic motor. The driving apparatus described in JP2014-196094A is constituted to drive an auxiliary hydraulic pump by an electric motor using a battery as a driving source and to operate the hydraulic motor by the working oil discharged from the auxiliary hydraulic pump.

2016378702 11 Mar 2019

SUMMARY OF INVENTION [0004] In general, in mixer vehicles, the mixer drum is rotated during running in order to prevent separation of the ready-mixed concrete. Moreover, in recent years, a mixer vehicle including an idling stop function is in demand. [0005] If the mixer driving apparatus described in JP2012-91729A is applied to a mixer vehicle including the idling stop function as it is, since the running engine is stopped during the idling stop, the hydraulic pump driven by the running engine is also stopped. Thus, in the mixer driving apparatus described in JP2012-91729A, the mixer drum cannot be rotated by the hydraulic pump during the idling stop.

[0006] Thus, as in the driving apparatus described in JP2014-196094A, by providing an auxiliary hydraulic pump driven by an electric motor using a battery as a power source, and the hydraulic motor can be rotated by this auxiliary hydraulic pump.

[0007] However, in the mixer driving apparatus described in JP2014-196094A, the switching valve is maintained at a communication position during the idling stop. Thus, the working oil discharged from the auxiliary pump flows into the hydraulic pump through the switching valve, and there is a concern that a flowrate of the working oil discharged from the auxiliary pump is reduced. If the flowrate of the working oil discharged from the auxiliary pump is reduced as above, rotation of the mixer drum runs short. [0008] The present invention seeks to provide a mixer drum driving apparatus which can stably supply the working fluid discharged from the auxiliary fluid pressure pump to the mixer drum during the idling stop.

[0009] According to an aspect of the present invention, a mixer drum driving apparatus mounted on a vehicle and configured to rotationally drive a mixer drum capable of loading a ready-mixed concrete, includes: a fluid pressure pump driven by an engine of the vehicle; a fluid pressure motor

2016378702 11 Mar 2019 operated by a working fluid discharged from the fluid pressure pump and configured to drive the mixer drum rotationally; a control valve configured to control a flow of the working fluid from the fluid pressure pump to the fluid pressure motor; an electric motor rotated by electricity during idling stop of the engine; an auxiliary fluid pressure pump driven by rotation of the electric motor, the auxiliary fluid pressure pump being configured to discharge the working fluid and operate the fluid pressure motor; and a backflow preventing portion configured to prevent a backflow of the working fluid from the control valve toward the fluid pressure pump.

[0009a] According to another aspect, the present invention provides a mixer drum driving apparatus mounted on a vehicle and configured to rotationally drive a mixer drum capable of loading a ready-mixed concrete, comprising: a fluid pressure pump driven by an engine of the vehicle; a fluid pressure motor operated by a working fluid discharged from the fluid pressure pump and configured to rotate/drive the mixer drum; a control valve manually switched to any one of a normal rotation position where the working fluid discharged from the fluid pressure pump is led to the fluid pressure motor so that the mixer drum is rotated normally, a reverse rotation position where the working fluid discharged from the fluid pressure pump is led to the fluid pressure motor so that the mixer drum is rotated reversely, and a shut-off position where a flow of the working fluid between the fluid pressure pump and the fluid pressure motor is shut off, the control valve being configured to control the flow of the working fluid from the fluid pressure pump to the fluid pressure motor; an electric motor rotated by electricity during idling stop of the engine; an auxiliary fluid pressure pump driven by rotation of the electric motor, the auxiliary fluid pressure pump being configured to discharged the working fluid

2016378702 11 Mar 2019

- 3Aand operate the fluid pressure motor; and a backflow preventing portion configured to prevent a backflow of the working fluid from the control valve toward the fluid pressure pump during the idling stop and when the control valve is at the normal rotation position.

BRIEF DESCRIPTION OF DRAWINGS [0010] [Fig. 1] Fig. 1 is a plan view of a mixer vehicle on which a mixer drum driving apparatus according to an embodiment of the present invention is mounted.

[Fig. 2] Fig. 2 is a hydraulic circuit diagram of the mixer drum driving apparatus according to the embodiment of the present invention.

[Fig. 3] Fig. 3 is a hydraulic circuit diagram during idling stop of the mixer drum driving apparatus according to the embodiment of the present invention.

[Fig. 4] Fig. 4 is a hydraulic circuit diagram illustrating a variation of the mixer drum driving apparatus according to the embodiment of the present invention.

[Fig. 5] Fig. 5 is a hydraulic circuit diagram illustrating a variation of the mixer drum driving apparatus according to the embodiment of the present invention.

[Fig. 6] Fig. 6 is a hydraulic circuit diagram illustrating a variation of the

GS11960/PCT-2068 DESCRIPTION

- 4 mixer drum driving apparatus according to the embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS [0011] A mixer drum driving apparatus 100 according to an embodiment of the present invention will be described below by referring to the attached drawings.

[0012] First, by referring to Fig. 1, an entire constitution of a mixer vehicle 10 on which the mixer drum driving apparatus 100 is mounted will be described.

[0013] The mixer vehicle 10 includes a running engine 3 for a vehicle 1, a mixer drum 2 mounted on the vehicle 1 and capable of loading a ready-mixed concrete, and the mixer drum driving apparatus 100 configured to rotate/drive the mixer drum 2. The mixer vehicle 10 is to transport the ready-mixed concrete loaded in the mixer drum 2.

[0014] The mixer drum 2 is a container having a cylindrical shape with a bottom mounted rotatably on the vehicle 1. The mixer drum 2 is mounted so that its rotating shaft is directed to a longitudinal direction of the vehicle 1. The mixer drum 2 is mounted with longitudinal inclination so that it gradually becomes higher toward a rear part of the vehicle 1. The mixer drum 2 has an opening portion formed on its rear end, and the ready-mixed concrete can be input and discharged through the opening portion.

[0015] The mixer drum 2 is supported on the vehicle 1 at three points, that is, a front part where an output shaft of the mixer drum driving apparatus 100 is connected and left and right on the rear part. The rear part of the mixer drum 2 is rotatably supported by a roller (not shown). The mixer drum 2 is rotated/driven by using the running engine 3 as a power source.

GS11960/PCT-2068 DESCRIPTION

- 5 [0016] Subsequently, the mixer drum driving apparatus 100 will be described by referring to Figs. 2 and 3. Fig. 2 is a view illustrating a hydraulic circuit of the mixer drum driving apparatus 100.

[0017] The mixer drum driving apparatus 100 is driven by rotation of the running engine 3 and rotates/ drives the mixer drum 2 by a fluid pressure of a working fluid. A rotating motion of a crank shaft in the running engine 3 is transmitted to the mixer drum driving apparatus 100 by a power take-off mechanism 4 (PTO: Power-take-off) for normally taking off the power from the running engine 3.

[0018] In the mixer drum driving apparatus 100, a working oil is used as the working fluid. Instead of the working oil, another non-compressive fluid may be used as the working fluid. The mixer drum driving apparatus 100 includes a hydraulic pump 5 as a fluid pressure pump driven by the running engine 3, a hydraulic motor 6 as a fluid pressure motor operated by the working oil discharged from the hydraulic pump 5 and configured to rotate/drive the mixer drum 2, a control valve 8 configured to control a flow of the working oil from the hydraulic pump 5 to the hydraulic motor 6, a charge pump 9 driven by the running engine 3 and provided coaxially with the hydraulic pump 5, and a check valve 14 provided in a passage between the hydraulic pump 5 and the control valve 8 and serving as a backflow preventing portion preventing a backflow of the working oil from the control valve 8 toward the hydraulic pump 5.

[0019] The hydraulic pump 5 is rotated/driven by power normally taken off from the running engine 3 through the power take-off mechanism 4. The hydraulic pump 5 is a swash-plate type axial piston pump with a variable

GS11960/PCT-2068 DESCRIPTION

- 6 volume.

[0020] The hydraulic motor 6 is a swash-plate type axial piston motor with a fixed volume. The hydraulic motor 6 is rotated/driven upon receipt of supply of the working oil discharged from the hydraulic pump 5. The mixer drum 2 is connected to the hydraulic motor 6 through a speed reducer 7. The hydraulic motor 6 is switched by the control valve 8 to a normal rotation or a reverse rotation. When the mixer drum 2 is rotated normally by the hydraulic motor 6, the ready-mixed concrete in the mixer drum 2 is agitated. On the other hand, when the mixer drum 2 is rotated reversely by the hydraulic motor 6, the ready-mixed concrete in the mixer drum 2 is discharged from the opening portion on the rear end to the outside. In this embodiment, the hydraulic motor 6 is described as a swash-plate type axial piston motor with a fixed volume, but this is not limiting, and the hydraulic motor 6 may be a swash-plate type axial piston motor with a variable volume.

[0021] A closed circuit 20 is provided between the hydraulic pump 5 and the hydraulic motor 6, and the working oil is circulated through this closed circuit 20. The closed circuit 20 is constituted by a return passage (pump suction passage) 21 connecting a suction port of the hydraulic pump 5 and the control valve 8, a supply passage (pump ejection passage) 22 connecting an ejection port of the hydraulic pump 5 and the control valve 8, and first and second supply/discharge passages 23, 24 connecting the control valve 8 and each of two ports provided in the hydraulic motor 6.

[0022] The control valve 8 includes a normal rotation position A where the working oil discharged by the hydraulic pump 5 is led to the hydraulic motor 6 so that the mixer drum 2 is rotated normally, a reverse rotation position B

GS11960/PCT-2068 DESCRIPTION

- 7 where the working oil discharged by the hydraulic pump 5 is led to the hydraulic motor 6 so that the mixer drum 2 is rotated reversely, and a shut-off position C where the flow of the working oil from the hydraulic pump 5 to the hydraulic motor 6 is shut off. The control valve 8 is switched by an operation of an operation lever 8a by an operator.

[0023] The charge pump 9 discharges the working oil suctioned from a tank T through a passage 25 to a charge passage 26. This working oil is filled in the return passage 21 from the charge passage 26 through the check valve 15. [0024] The charge passage 26 communicates with the tank T through a relief valve 50. When a pressure in the charge passage 26 is increased over a predetermined value, the relief valve 50 is opened, and an excess working oil discharged from the charge pump 9 is returned to the tank T.

[0025] The check valve 14 is provided in the supply passage 22 connecting the hydraulic pump 5 and the control valve 8 so as to prevent a backflow of the working oil from the control valve 8 toward an ejection port side of the hydraulic pump 5.

[0026] The mixer drum driving apparatus 100 further includes a load sensing valve 30 executing adjustment so that a differential pressure between a load pressure generated in either one of the first and second supply/discharge passages 23 and 24 and a pressure of the supply passage 22 (pump ejection pressure) becomes a predetermined value and a cut-off valve 40 adjusting a pump ejection volume of the hydraulic pump 5 in accordance with the pressure of the supply passage 22 (pump ejection pressure).

[0027] To the load sensing valve 30, a load pressure generated in either one of the first and second supply/discharge passages 23 and 24 and a pump

GS11960/PCT-2068 DESCRIPTION

- 8 ejection pressure of the supply passage 22 are led as a pilot pressure so that they are opposed against each other. The load sensing valve 30 adjusts the pilot pressure led to an actuator 5a through an actuator passage 27 so that the differential pressure between them becomes the predetermined value.

[0028] The load sensing valve 30 includes a position F where the actuator 5a communicates with the tank T and a position G where the actuator 5a communicates with the supply passage 22. The load sensing valve 30 is biased to the position F by a biasing force of a spring 34 at all times.

[0029] First and second pilot pressure passages 31 and 32 are connected to the load sensing valve 30. The first pilot pressure passage 31 communicates with high pressure sides (load pressure sides) of the first and second supply/discharge passages 23 and 24 through a high-pressure selection valve 33. The second pilot pressure passage 32 is connected to the supply passage 22. For the high-pressure selection valve 33, a shuttle valve is used, for example.

[0030] In the load sensing valve 30, the load pressure led from the first pilot pressure passage 31 acts in a direction for switching to the position F together with the biasing force of the spring 34, and the pressure (pump ejection pressure) of the supply passage 22 led from the second pilot pressure passage 32 acts in the direction for switching to the position G against the load pressure led from the first pilot pressure passage 31 and the biasing force of the spring 34.

[0031] A pressure (pump ejection pressure) of the supply passage 22 is led as a pilot pressure to the cut-off valve 40. When the pump discharge pressure is increased over a predetermined value, the cut-off valve 40 heightens the

GS11960/PCT-2068 DESCRIPTION

- 9 pilot pressure led to the actuator 5a and reduces the pump ejection volume of the hydraulic pump 5.

[0032] The cut-off valve 40 includes a position H where the actuator 5a communicates with the tank T and a position I where the actuator 5a communicates with the supply passage 22.

[0033] A pilot pressure passage 41 of the cut-off valve 40 is connected to the supply passage 22. In the cut-off valve 40, a biasing force of a spring 42 acts in a direction for switching to the position H, and the pilot pressure (pump ejection pressure) led from the pilot pressure passage 41 acts in a direction for switching to the position I against the biasing force of the spring 42.

[0034] When the mixer drum 2 is being driven, in a state where the pressure (pump ejection pressure) of the supply passage 22 is not higher than the predetermined value, the cut-off valve 40 is held at the position H, and the actuator passage 27 connecting the load sensing valve 30 and the actuator 5a is opened. In this state, the load pressure generated in either one of the first and second supply/discharge passages 51 and 52 and the pressure (pump ejection pressure) of the supply passage 22 are led as a pilot pressure to the load sensing valve 30 so that they are opposed against each other. The load sensing valve 30 adjusts the pressure of the actuator passage 27 led to the actuator 5a in accordance with the differential pressure between them. As a result, the pump ejection volume of the hydraulic pump 5 is adjusted by the actuator 5a so that the differential pressure between the load pressure generated in either one of the first and second supply/discharge passages 23 and 24 and the pressure (pump ejection pressure) of the supply passage 22 becomes the predetermined value.

GS11960/PCT-2068 DESCRIPTION

- 10 [0035] When the driving of the mixer drum 2 is to be stopped, the control valve 8 is switched to the shut-off position C, and the communication between the supply passage 22 and the first and second supply/discharge passages 23 and 24 is shut off. At this time, if the pump ejection pressure is increased over the predetermined value, the pilot pressure (pump ejection pressure) led from the pilot pressure passage 41 rises and thus, the cut-off valve 40 is switched from the position H to the position I against the biasing force of the spring 42. As a result, the actuator 5a communicates with the supply passage 22 and thus, the pressure (pump ejection pressure) of the supply passage 22 is led to the actuator 5a, and the pump ejection volume of the hydraulic pump 5 is reduced.

[0036] The mixer drum driving apparatus 100 further includes an electric motor 11 driven by electricity accumulated in a battery, not shown, an auxiliary hydraulic pump 12 as an auxiliary fluid pressure pump driven by rotation of the electric motor 11, the auxiliary hydraulic pump 12 discharging the working oil, and the auxiliary hydraulic pump 12 operating the hydraulic motor 6, and an opening/closing valve 13 provided in the discharge passage 29 connecting the second supply/discharge passage 24 and the tankT and the opening/closing valve 13 opening/closing the discharge passage 29.

[0037] An output shaft of the electric motor 11 is connected to a rotating shaft of the auxiliary hydraulic pump 12. The electric motor 11 is driven in a state where the idling of the running engine 3 is stopped, that is, during the idling stop and drives the auxiliary hydraulic pump 12.

[0038] The auxiliary hydraulic pump 12 suctions the working oil reserved in the tank T and discharges it to an auxiliary supply passage 28. The

GS11960/PCT-2068 DESCRIPTION

- 11 working oil discharged to the auxiliary supply passage 28 is supplied to the first supply/discharge passage 23 through a check valve 16. As a result, the working oil discharged from the auxiliaiy hydraulic pump 12 is supplied to the hydraulic motor 6 through the auxiliary supply passage 28 and the first supply/discharge passage 23 and rotates the hydraulic motor 6 normally. [0039] The electric motor 11 and the auxiliary hydraulic pump 12 are configured to rotate/drive the mixer drum 2 so that the agitation of the ready-mixed concrete loaded in the mixer drum 2 is not stopped while the running engine 3 is at idling stop.

[0040] The opening/closing valve 13 is an electromagnetic switching valve controlled by a controller, not shown. The opening/closing valve 13 includes a position D where the communication between the second supply/discharge passage 24 and the tank T is shut off and a position E where the second supply/discharge passage 24 and the tank T communicate each other. The opening/closing valve 13 is biased by the spring so as to hold the D position at a normal state. An electric current is applied by the controller during the idling stop, and the opening/closing valve 13 is switched to the E position. [0041] An operation of the mixer drum driving apparatus 100 constituted as above will be described.

[0042] When the running engine 3 is driven, the hydraulic pump 5 is driven, and the working oil is discharged to the supply passage 22. During transportation of the ready-mixed concrete, the operator operates the operation lever 8a and switches the control valve 8 from the shut-off position C to the normal rotation position A. As a result, the working oil discharged to the supply passage 22 is supplied to the hydraulic motor 6 through the check

GS11960/PCT-2068 DESCRIPTION

- 12 valve 14, the control valve 8, and the first supply/discharge passage 23 and rotates the hydraulic motor 6 normally.

[0043] The rotation of the hydraulic motor 6 is transmitted to the mixer drum 2 through the speed reducer 7 and rotates the mixer drum 2 normally. As a result, the ready-mixed concrete in the mixer drum 2 is agitated. The working oil discharged from the hydraulic motor 6 is returned to the suction port of the hydraulic pump 5 through the second supply/discharge passage 24, the control valve 8, and the return passage 21.

[0044] As described above, by switching the control valve 8 to the normal rotation position A while the running engine 3 is being driven, the mixer drum 2 is rotated normally. As a result, the ready-mixed concrete is agitated in the mixer drum 2, and separation is prevented.

[0045] If the operator operates the operation lever 8a and switches the control valve 8 from the shut-off position C to the reverse rotation position B while the running engine 3 is being driven, the working oil discharged to the supply passage 22 is supplied to the hydraulic motor 6 through the check valve 14, the control valve 8, and the second supply/discharge passage 24 and rotates the hydraulic motor 6 reversely. The rotation of the hydraulic motor 6 is transmitted to the mixer drum 2 through the speed reducer 7 and rotates the mixer drum 2 reversely. As a result, the ready-mixed concrete in the mixer drum 2 is discharged from the opening portion on the rear end to the outside. The working oil discharged from the hydraulic motor 6 is returned to the suction port of the hydraulic pump 5 through the first supply/discharge passage 23, the control valve 8, and the return passage 21.

[0046] When the mixer drum 2 (hydraulic motor 6) is rotated/driven, in a

GS11960/PCT-2068 DESCRIPTION

- 13 state where the pressure (pump ejection pressure) of the supply passage 22 is not higher than the predetermined value, the cut-off valve 40 is held at the position H and opens the actuator passage 27 connecting the load sensing valve 30 and the actuator 5a. The load sensing valve 30 adjusts the pressure led to the actuator 5a from the supply passage 22 through the actuator passage 27 so that the differential pressure between the load pressure generated in either one of the first and second supply/discharge passages 23 and 24 and the pressure (pump ejection pressure) of the supply passage 22 becomes the predetermined value. As a result, the pump ejection volume of the hydraulic pump 5 is adjusted by the actuator 5a so that the differential pressure between the load pressure generated in either one of the first and second supply/discharge passages 23 and 24 and the pressure (pump ejection pressure) of the supply passage 22 becomes the predetermined value.

[0047] When the mixer vehicle 10 is stopped by a signal or the like during running, idling of the running engine 3 is stopped into an idling stop state. As described above, when the running engine 3 is stopped, the hydraulic pump 5 also stops the rotation, and the hydraulic motor 6 cannot be rotated/driven anymore by the hydraulic pump 5. At this time, the auxiliary hydraulic pump 12 is driven by the electric motor 11 using the battery as the power source, and the working oil is supplied to the first supply/discharge passage 23 through the auxiliary supply passage 28. As a result, the working oil discharged from the auxiliary hydraulic pump 12 is supplied to the hydraulic motor 6 through the auxiliary supply passage 28 and the first supply/discharge passage 23 and rotates the hydraulic motor 6 normally. At the same time, an electric current is applied to the opening/closing valve 13 from a controller, not shown,

GS11960/PCT-2068 DESCRIPTION

- 14 and the opening/closing valve 13 is switched to the position E (see Fig. 3). As a result, the working oil discharged from the hydraulic motor 6 is returned to the tank T through the second supply/discharge passage 24, the discharge passage 29, and the opening/closing valve 13.

[0048] At this time, as illustrated in Fig. 3, since the control valve 8 is maintained at the normal rotation position A, the working oil discharged from the auxiliary hydraulic pump 12 flows into the supply passage 22 through the control valve 8 as indicated by an arrow in Fig. 3. However, since the check valve 14 is provided in the supply passage 22, the working oil discharged from the auxiliary hydraulic pump 12 is prevented from flowing into the hydraulic pump 5. Therefore, since inflow of the working oil discharged from the auxiliary hydraulic pump 12 into the hydraulic pump 5 and reduction of the flowrate of the working oil discharged from the auxiliary hydraulic pump 12 can be prevented, the rotation of the mixer drum 2 can be prevented from running short during the idling stop.

[0049] If the idling stop state is canceled since the operator steps on an accelerator pedal or the like, the running engine 3 is driven again. As a result, the hydraulic pump 5 is rotated/ driven, and the working oil is discharged to the supply passage 22. At the same time, the electric motor 11 is stopped, and application of the electric current to the opening/closing valve 13 from the controller is stopped. Due to the stop of the electric motor 11, the supply of the working oil from the auxiliary hydraulic pump 12 to the auxiliary supply passage 28 is stopped. Due to the stop of the application of the electric current from the controller, the opening/closing valve 13 is switched to the position D and thus, the communication between the second

GS11960/PCT-2068 DESCRIPTION

- 15 supply/discharge passage 24 and the tank T is shut off.

[0050] As described above, the hydraulic motor 6 is rotated/driven by the working oil discharged from the hydraulic pump 5 again.

[0051] According to the mixer drum driving apparatus 100 described above, the following effects are exerted.

[0052] The mixer drum driving apparatus 100 includes the check valve 14 configured to prevent a backflow of the working oil from the control valve 8 toward the hydraulic pump 5. As a result, the working oil discharged from the auxiliary hydraulic pump 12 is prevented from flowing into the hydraulic pump 5 side during the idling stop. Therefore, since the working oil discharged from the auxiliary hydraulic pump 12 can be supplied to the mixer drum 2 stably during the idling stop, it is possible to prevent insufficient rotation of the mixer drum 2..

[0053] If the mixer drum driving apparatus 100 does not include the check valve 14, the communication between the auxiliary hydraulic pump 12 and the supply passage 22 needs to be shut off by switching the control valve 8 from the normal rotation position A to the shut-off position C every time the state is switched to the idling stop state. Particularly if the control valve 8 is of a manual operation type, switching of the control valve 8 to the shut-off position C at each idling stop is a large burden for the operator.

[0054] Since the mixer drum driving apparatus 100 includes the check valve 14, even if the state is switched to the idling stop state, there is no need to switch the control valve 8 to the shut-off position C. That is, even if the control valve 8 is maintained at the normal rotation position A during the idling stop, the working oil discharged from the auxiliary hydraulic pump 12

GS11960/PCT-2068 DESCRIPTION

- 16 can be prevented from flowing into the hydraulic pump 5. Therefore, an operation for switching the control valve 8 can be made unnecessary.

[0055] Moreover, by employing the check valve 14 as a backflow preventing portion, constitution with a simple structure can be realized. Moreover, since the check valve 14 does not have to be controlled, there is no need to provide a signal or wiring for control. Therefore, the mixer drum driving apparatus 100 can be realized with the simple structure.

[0056] In the case of the constitution of switching the control valve 8 from the normal rotation position A to the shut-off position C during the idling stop, when the running engine 3 is driven again from the idling stop state, the control valve 8 needs to be switched from the shut-off position C to the normal rotation position A and thus, a time lag is generated when the driving by the auxiliary hydraulic pump 12 is switched to the driving by the hydraulic pump 5. However, in the mixer drum driving apparatus 100, since the control valve 8 is maintained at the normal rotation position A when the running engine 3 is driven again from the idling stop state, there is no need to switch the control valve 8. Therefore, the driving by the auxiliary hydraulic pump 12 can be smoothly switched to the driving by the hydraulic pump 5. As a result, since the supply of the working oil to the hydraulic motor 6 is not discontinued, the mixer drum 2 can be rotated stably.

[0057] As the control valve 8, switching means of a manual type was described in the example but an electromagnetic operation type may also be used. In this case, too, since the control valve 8 can be still maintained at the normal rotation position A during the idling stop, control of switching the control valve 8 to the shut-off position C can be made unnecessary. Therefore,

GS11960/PCT-2068 DESCRIPTION

- 17 the control can be simplified.

[0058] Moreover, the check valve 14 is provided between the hydraulic pump 5 and the control valve 8, but as illustrated in Fig. 4, it may be provided in the control valve 8 so that it functions only when the control valve 8 is at the normal rotation position A. As a result, when the control valve 8 is at the normal rotation position A, the check valve 14 functions so as to prevent the backflow of the working oil from the control valve 8 toward the hydraulic pump 5. In contrast, when the control valve 8 is at the reverse rotation position B, the check valve 14 does not function. Specifically explaining, the mixer drum 2 is not rotated reversely during running of the mixer vehicle 10 at normal time That is, since the control valve 8 is not switched to the reverse rotation position B during the idling stop (during running), there is no influence even if the backflow of the working oil from the control valve 8 toward the hydraulic pump 5 is not considered at the reverse rotation position B. Moreover, if the mixer drum 2 is to be rotated reversely (when the control valve 8 is at the reverse rotation position B) when the mixer vehicle 10 is stopped or the like, the working oil discharged from the hydraulic pump 5 is supplied to the hydraulic motor 6 without being influenced of a pressure loss by the check valve 14. Therefore, by employing such constitution, since the influence of the pressure loss of the check valve 14 is not given when the mixer drum 2 is rotated reversely, efficiency of the hydraulic pump 5 can be improved, and energy saving can be promoted.

[0059] In the aforementioned embodiment, the check valve 14 as a backflow preventing portion was described in an example, but as illustrated in Fig. 5, an electromagnetic switching valve 60 may be employed as the backflow

GS11960/PCT-2068 DESCRIPTION

- 18 preventing portion. In this case, by controlling the opening/closing valve 13 and the electromagnetic switching valve 60 synchronously, they function similarly to the case where the check valve 14 is employed.

[0060] Furthermore, as illustrated in Fig. 6, a pilot operation type switching valve 160 may be employed as a backflow preventing portion. A variation using the pilot operation type switching valve 160 will be described below. [0061] In this variation, the pilot operation type switching valve 160 is provided instead of the check valve 14 in the supply passage 22, and an opening/closing valve 113 is provided instead of the opening/closing valve 13 in the discharge passage 29.

[0062] The pilot operation type switching valve 160 includes a position J where the supply passage 22 is opened and a position K where the supply passage 22 is shut off. The pilot operation type switching valve 160 is constituted as a normally-open type. Specifically, in a state where the pilot pressure does not act on a pilot chamber 160a, it is held at the position J by a biasing force of a spring 160b, while in a state where the pilot pressure acts on the pilot chamber 160a, a valve body is moved against the biasing force of the spring 160b and is switched to the position K. To the pilot chamber 160a, the pilot pressure is supplied through a pilot passage 161 branched from an upstream side of the check valve 16 in the auxiliary supply passage 28.

[0063] A pilot pressure discharge passage 162 branched from the auxiliary supply passage 28 and communicating with the tank T is connected to the opening/closing valve 113. The opening/closing valve 113 is an electromagnetic switching valve controlled by a controller, not shown, similarly to the opening/closing valve 13. The opening/closing valve 113 includes a

GS11960/PCT-2068 DESCRIPTION

- 19 position DI where the communication between the second supply/discharge passage 24 and the tank T are shut off and the auxiliary supply passage 28 and the tank T communicate and a position El where the second supply/discharge passage 24 and the tank T communicate and the communication between the auxiliary supply passage 28 and the tank T are shut off.

[0064] While the engine is being driven, since the electric current is not applied to the opening/closing valve 113, the opening/closing valve 113 is held at the DI position by the biasing force of the spring. In this state, since the auxiliary hydraulic pump 12 is stopped, the working oil in the pilot chamber 160a is discharged to the tank T through the pilot passage 161, the pilot pressure discharge passage 162, and the opening/closing valve 113. As a result, the pilot operation type switching valve 160 is held at the position J, and the supply passage 22 is maintained in the open state. On the other hand, during the idling stop (engine stop), the electric current is applied to the opening/closing valve 113 by the controller, and the opening/closing valve 113 is switched to the El position. In this state, since the auxiliary hydraulic pump 12 is being driven, the working oil discharged from the auxiliary hydraulic pump 12 is supplied to the pilot chamber 160a through the pilot passage 161. As a result, the pilot operation type switching valve 160 is switched to the position K, and the supply passage 22 becomes a shut-off state When the pilot operation type switching valve 160 is controlled as above, the pilot operation type switching valve 160 functions similarly to the check valve 14, and the working oil discharged from the auxiliary hydraulic pump 12 during the idling stop is prevented from flowing into the hydraulic pump 5

GS11960/PCT-2068 DESCRIPTION

- 20 side.

[0065] The constitution, actions, and effects of the embodiments of the present invention constituted as above will be described collectively.

[0066] The mixer drum driving apparatus 100 includes a fluid pressure pump (hydraulic pump 5) driven by the engine (running engine 3) of the vehicle 1, the fluid pressure motor (hydraulic motor 6) configured to drive the mixer drum 2 rotationally by being operated by the working fluid discharged from the fluid pressure pump (hydraulic pump 5), the control valve 8 configured to control the flow of the working fluid from the fluid pressure pump (hydraulic pump 5) to the fluid pressure motor (hydraulic motor 6), the electric motor 11 rotated by the electricity during the idling stop of the engine (running engine 3), the auxiliary fluid pressure pump (auxiliary hydraulic pump 12) driven by the rotation of the electric motor 11, the auxiliary fluid pressure pump (auxiliary hydraulic pump 12) being configured to discharge the working fluid and operate the fluid pressure motor (hydraulic motor 6), and the backflow preventing portion (the checkvalve 14, the electromagnetic switching valve 60, the pilot operation type switching valve 160) configured to prevent the backflow of the working fluid from the control valve 8 toward the fluid pressure pump (hydraulic pump 5).

[0067] In this constitution, since the backflow preventing portion (the check valve 14, the electromagnetic switching valve 60, the pilot operation type switching valve 160) configured to prevent the backflow of the working fluid from the control valve 8 toward the fluid pressure pump (hydraulic pump 5) is provided, the working fluid discharged from the auxiliary fluid pressure pump (auxiliaiy hydraulic pump 12) is prevented from flowing into the fluid pressure

GS11960/PCT-2068 DESCRIPTION

- 21 pump (hydraulic pump 5) side. As a result, the rotation of the mixer drum 2 can be prevented from running short.

[0068] Moreover, in the mixer drum driving apparatus 100, the control valve 8 has the normal rotation position A where the working fluid discharged from the fluid pressure pump (hydraulic pump 5) is led to the fluid pressure motor (hydraulic motor 6) so that the mixer drum 2 is rotated normally, the reverse rotation position B where the working fluid discharged from the fluid pressure pump (hydraulic pump 5) is led to the fluid pressure motor (hydraulic motor 6) so that the mixer drum 2 is rotated reversely, and the shut-off position C where the flow of the working fluid from the fluid pressure pump (hydraulic pump 5) toward the fluid pressure motor (hydraulic motor 6) is shut off, and the control valve 8 is maintained at the normal rotation position A during the idling stop of the engine (running engine 3).

[0069] In this constitution, when the engine (running engine 3) is driven again from the idling stop state, since control valve 8 is maintained at the normal rotation position A, the driving by the auxiliaiy fluid pressure pump (auxiliaiy hydraulic pump 12) can be smoothly switched to the driving by the fluid pressure pump (hydraulic pump 5). As a result, since the supply of the working fluid to the fluid pressure motor (hydraulic motor 6) is not discontinued, the mixer drum 2 can be rotated stably.

[0070] Moreover, in the mixer drum driving apparatus 100, the backflow preventing portion is constituted by the check valve 14 provided between the fluid pressure pump (hydraulic pump 5) and the control valve 8.

[0071] In this constitution, by constituting the backflow preventing portion by the check valve 14, the structure can be made simple. Moreover, since

GS11960/PCT-2068 DESCRIPTION

- 22 there is no need to control the backflow preventing portion, the control of the mixer drum driving apparatus 100 can be simplified.

[0072] Moreover, in the mixer drum driving apparatus 100, the backflow preventing portion is constituted by the check valve 14 provided in the control valve 8 so that the check valve 14 functions only when the control valve 8 is at the normal rotation position A.

[0073] In this constitution, by constituting the backflow preventing portion by the check valve 14, the structure can be made simple. Moreover, since the check valve 14 functions only when the control valve 8 is at the normal rotation position A, the influence of the pressure loss by the check valve 14 is not given at the reverse rotation position B. As a result, efficiency of the fluid pressure pump (hydraulic pump 5) can be improved, and energy saving can be promoted.

[0074] Moreover, in the mixer drum driving apparatus 100, the backflow preventing portion is constituted by the switching valve (the electromagnetic switching valve 60, the pilot operation type switching valve 160).

[0075] Moreover, in the mixer drum driving apparatus 100, the switching valve (pilot operation type switching valve 160) is a pilot operation type switching valve (pilot operation type switching valve 160) switched by the pilot pressure supplied from the auxiliary fluid pressure pump (auxiliary hydraulic pump 12).

[0076] Embodiments of this invention were described above, but the above embodiments are merely examples of applications of this invention, and the technical scope of this invention is not limited to the specific constitutions of the above embodiments.

2016378702 11 Mar 2019

- 23 [0077] In the aforementioned embodiment, the hydraulic pump 5 is constituted to be driven by the running engine 3, but the hydraulic pump 5 may be constituted to be driven by an engine different from the running engine

3.

[0078] The electromagnetic switching valve 60 and the pilot operation type switching valve 160 may be provided between a merging point with the auxiliary supply passage 28 in the first supply/discharge passage 23 and the control valve 8. Moreover, the electromagnetic switching valve 60 and the pilot operation type switching valve 160 may be provided in the control valve 8 so that it functions only when the control valve 8 is at the normal rotation position A similarly to the variation illustrated in Fig. 4.

[0079] This application claims priority based on Japanese Patent Application No.2015-251674 filed with the Japan Patent Office on December 24, 2015, the entire contents of which are incorporated into this specification. [0080] Throughout this specification and the claims which follow, unless the context requires otherwise, the word comprise, and variations such as comprises or comprising, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0081] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as, an acknowledgement or admission or any form of suggestion that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

2016378702 11 Mar 2019

Claims

1. A mixer drum driving apparatus mounted on a vehicle and configured to rotationally drive a mixer drum capable of loading a ready-mixed concrete, comprising:

a fluid pressure pump driven by an engine of the vehicle; a fluid pressure motor operated by a working fluid discharged from the fluid pressure pump and configured to rotate/drive the mixer drum;

a control valve manually switched to any one of a normal rotation position where the working fluid discharged from the fluid pressure pump is led to the fluid pressure motor so that the mixer drum is rotated normally, a reverse rotation position where the working fluid discharged from the fluid pressure pump is led to the fluid pressure motor so that the mixer drum is rotated reversely, and a shut-off position where a flow of the working fluid between the fluid pressure pump and the fluid pressure motor is shut off, the control valve being configured to control the flow of the working fluid from the fluid pressure pump to the fluid pressure motor;

an electric motor rotated by electricity during idling stop of the engine; an auxiliary fluid pressure pump driven by rotation of the electric motor, the auxiliaiy fluid pressure pump being configured to discharged the working fluid and operate the fluid pressure motor; and a backflow preventing portion configured to prevent a backflow of the working fluid from the control valve toward the fluid pressure pump during the idling stop and when the control valve is at the normal rotation position.

2. The mixer drum driving apparatus according to claim 1, wherein

2016378702 11 Mar 2019

- 25 the control valve is maintained at the normal rotation position during the idling stop of the engine and is also maintained at the normal rotation position when the engine is driven again from the idling stop state.

3. The mixer drum driving apparatus according to claim 1, wherein the backflow preventing portion is constituted by a check valve and is provided between the fluid pressure pump and the control valve.

4. The mixer drum driving apparatus according to claim 1, wherein the backflow preventing portion is constituted by a check valve and is provided on in the control valve so that it the check valve functions only when the control valve is at the normalforward rotation position.

5. The mixer drum driving apparatus according to claim 1, wherein the backflow preventing portion is constituted by a switching valve.

6. The mixer drum driving apparatus according to claim 5, wherein the switching valve is a pilot operation type switching valve switched by a pilot pressure supplied from the auxiliary fluid pressure pump.

7. The mixer drum driving apparatus according to claim 1, wherein a closed circuit is provided between the fluid pressure pump and the fluid pressure motor;

the closed circuit has a supply passage connecting an discharge port of the fluid pressure pump and the control valve, a return passage connecting a

2016378702 11 Mar 2019

- 26suction port of the fluid pressure pump and the control valve, a first supply/discharge passage connected to the supply passage and one of ports of the fluid pressure motor when the control valve is at the normal rotation position, and a second supply/discharge passage connected to the return passage and the other port of the fluid pressure motor when the control valve is at the normal rotation position;

an auxiliaiy supply passage connecting the auxiliary fluid pressure pump and the first supply/discharge passage is provided; and the backflow preventing portion is provided closer to the fluid pressure pump side than a merging point between the auxiliary supply passage and the first supply/discharge passage.

8. The mixer drum driving apparatus according to claim 7, further comprising:

a tank for reserving a working fluid; and an opening/closing valve provided in a discharge passage connecting the second supply/discharge passage and the tank, the opening/closing valve opening/closing the discharge passage, wherein the opening/closing valve shuts off the discharge passage at normal state and opens the discharge passage during the idling stop.