JP2015086854A - Work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable stable continuous reproduction of a DPF.SOLUTION: There is provided a work vehicle having an engine with an exhaust emission control device, the work vehicle including an exhaust temperature detection part which detects the exhaust temperature of the engine, a differential pressure detection part which detects differential pressure between an exhaust upstream point and an exhaust downstream point of the exhaust emission control device, other constitution, and a control part which controls various operations of the work vehicle. When the exhaust temperature and the differential pressure meet predetermined conditions, and an operation lever for operating the work machine by acquiring an engine load rate of the engine and performing control based upon the exhaust temperature, differential pressure, and engine load rate is not operated, the control part switches and drives an electromagnetic changeover valve and guides working oil to an oil cooler through hydraulic pressure load means so as to increase a load placed on the engine.

Description

  The present invention relates to a work vehicle, and more particularly to a work vehicle such as an agricultural machine or a construction machine.

  Conventionally, DPF (Diesel Particulate Filter) for collecting PM (Particulate Matter) etc. in exhaust gas in work vehicles such as agricultural machines and construction machines equipped with diesel engines (hereinafter also simply referred to as “engines”) A filter equipped with a filter for removing particulate matter in diesel exhaust is known. In such work vehicles, DPF regeneration control, that is, control to regenerate the DPF by reburning and removing PM accumulated in the DPF (see Patent Document 1).

  In Patent Document 1, the PM accumulation amount in the DPF is calculated based on the pressure difference detected by the DPF differential pressure sensor provided in the DPF, and the intake throttle device based on the calculation result of the PM accumulation amount, A technique for performing regeneration control of a DPF by controlling the operation of an exhaust throttle device or a common rail is disclosed.

JP 2013-002362 A

  By the way, in a foot accelerator type work vehicle such as a wheel loader, for example, the engine load factor may not increase and the exhaust temperature may not increase depending on the work mode. Even in such a situation, it was preferable to perform stable continuous regeneration of the DPF.

  It is also conceivable to forcibly increase the engine load factor by applying a dummy load to the engine in order to perform stable continuous regeneration of the DPF.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a work vehicle that can enable stable continuous regeneration of a DPF.

  A work vehicle according to the present invention is a work vehicle having an engine equipped with an exhaust purification device, an exhaust temperature detection unit for detecting an exhaust temperature of the engine, and a differential pressure between the exhaust upstream and the exhaust downstream of the exhaust purification device. A differential pressure detection unit that detects a hydraulic pressure, a hydraulic cylinder that operates a work machine mounted on the work vehicle, a hydraulic control valve that controls operation of the hydraulic cylinder, and a work machine that supplies hydraulic oil to the hydraulic control valve An electromagnetic switching valve provided between the hydraulic pump, the hydraulic control valve, and the work machine pump, and capable of switching between supplying hydraulic oil to the hydraulic control valve or hydraulic pressure means, and the hydraulic pressure An oil cooler that cools the hydraulic oil discharged from the load means, and a control unit that controls various operations of the work vehicle. The exhaust temperature and the differential pressure satisfy predetermined conditions, and the engine load factor of the engine is acquired, and control is performed based on the exhaust temperature, the differential pressure and the engine load factor, and the work implement is operated. When the operation lever is not operated, the electromagnetic switching valve is switched and the hydraulic fluid is guided to the oil cooler through the hydraulic load means to increase the load applied to the engine. And

  In the work vehicle according to the present invention, preferably, the work vehicle further includes an exhaust throttle provided between the engine and the exhaust purification device, and the control unit switches the engine when the electromagnetic switching valve is switched. The idle rotation speed of the engine is increased, and the load applied to the engine is increased by performing control to close the exhaust throttle.

  Further, the work vehicle according to the present invention preferably includes a forward / reverse changeover switch for operating forward / neutral / reverse of the work vehicle, and the control unit receives an operation instruction related to the neutrality of the forward / reverse changeover switch. Then, the electromagnetic switching valve is switched and the hydraulic fluid is guided to the oil cooler through the hydraulic load means to increase the load applied to the engine.

  In the work vehicle according to the present invention, preferably, the heat of the working oil flowing through the oil cooler is used as a heat source of the heater.

  In the work vehicle according to the present invention, it is preferable that the work vehicle further includes an electric fan that is provided near the oil cooler and blows air toward the oil cooler, and the control unit is configured so that the exhaust temperature and the differential pressure are predetermined. When the condition is satisfied, the electric fan is further operated.

  According to the present invention, stable continuous regeneration of a DPF can be enabled.

It is a figure showing an example of composition of a work vehicle concerning a first embodiment of the present invention. It is a flowchart which shows the operation example of the work vehicle which concerns on 1st embodiment of this invention. It is a figure which shows the structural example of the work vehicle which concerns on 2nd embodiment of this invention. It is a flowchart which shows the operation example of the work vehicle which concerns on 2nd embodiment of this invention. It is a figure for supplementary explanation of an example of operation of a work vehicle concerning a second embodiment of the present invention. It is a figure for demonstrating the effect by the work vehicle which concerns on 2nd embodiment of this invention. It is a flowchart which shows the control logic of operation | movement cancellation | release of the working vehicle which concerns on 2nd embodiment of this invention. It is a figure which shows the structural example of the work vehicle which concerns on 3rd embodiment of this invention. It is a flowchart which shows the operation example of the work vehicle which concerns on 3rd embodiment of this invention.

  A work vehicle according to the present invention is a work vehicle having an engine equipped with an exhaust purification device, an exhaust temperature detection unit for detecting an exhaust temperature of the engine, and a differential pressure between the exhaust upstream and the exhaust downstream of the exhaust purification device. A differential pressure detection unit that detects a hydraulic pressure, a hydraulic cylinder that operates a work machine mounted on the work vehicle, a hydraulic control valve that controls operation of the hydraulic cylinder, and a work machine that supplies hydraulic oil to the hydraulic control valve An electromagnetic switching valve provided between the hydraulic pump, the hydraulic control valve, and the work machine pump, and capable of switching between supplying hydraulic oil to the hydraulic control valve or hydraulic pressure means, and the hydraulic pressure An oil cooler that cools the hydraulic oil discharged from the load means, and a control unit that controls various operations of the work vehicle. The exhaust temperature and the differential pressure satisfy predetermined conditions, and the engine load factor of the engine is acquired, and control is performed based on the exhaust temperature, the differential pressure and the engine load factor, and the work implement is operated. When the operation lever is not operated, the electromagnetic switching valve is switched and the hydraulic fluid is guided to the oil cooler through the hydraulic load means to increase the load applied to the engine. And This enables stable continuous regeneration of the DPF. Embodiments of the present invention will be described below.

[Work vehicle configuration]
FIG. 1 is a diagram illustrating a configuration example of a work vehicle 1 according to the first embodiment of the present invention.

  A work vehicle 1 shown in FIG. 1 includes an engine 2, a common rail 3, a DPF 4, an exhaust temperature sensor (exhaust temperature detector) 4a, a DPF differential pressure sensor (differential pressure detector) 4b, an engine controller 5, a controller 6, and a controller 7. , Lift cylinder (hydraulic cylinder) 8, bucket cylinder (hydraulic cylinder) 9, PTO (Power take-off) 23, hydraulic control valve 10, hydraulic switching mechanism 11 (electromagnetic switching valve 11a, hydraulic relief valve 11b, electromagnetic solenoid 11c) , HST (Hydro Static Transmission) pump 12, HST motor 13, working machine pump 14, charge pump 15, oil tank 16, oil cooler 17, oil tank 18, electric fan 19, cabin 20, operation levers 21, 22, 24 , Operation state detection means 21a, 22a, 24 A structure having an exhaust throttle 31, and the like. Hereinafter, each component will be described. Although shown in FIG. 1, it is not essential in the first embodiment, and a configuration required in the other embodiment will be described in the other embodiment with reference to other drawings.

  The engine 2 is a diesel engine that spontaneously ignites by compressing air with a piston (not shown) and injecting fuel into high-temperature air in a cylinder (not shown). The engine 2 includes a common rail 3 and a DPF 4. The engine 2 rotationally drives a later-described HST pump 12 and the like.

  The common rail 3 stores high-pressure fuel and supplies the fuel to each fuel injection valve (not shown) that injects the fuel into the cylinder of the engine 2. The operation of the common rail 3 is controlled by the engine controller 5. Specifically, the fuel injection pressure, injection timing, and injection period (injection amount) in each fuel injection valve are controlled.

  The DPF 4 is an exhaust purification device that reduces PM, which is a particulate matter in the exhaust gas of the engine 2. The DPF 4 is attached to an exhaust port such as a muffler of the work vehicle 1. An exhaust temperature sensor 4a and a DPF differential pressure sensor 4b are attached to the DPF 4.

  The exhaust temperature sensor 4 a is a sensor that detects the exhaust temperature of the engine 2. The exhaust temperature sensor 4a is attached to the exhaust upstream side of the catalyst in the DPF 4, but may be attached to the exhaust downstream side. In the following description, the case where the exhaust temperature sensor 4a is attached to the exhaust upstream side will be described as an example. The DPF differential pressure sensor 4b is a sensor that detects a pressure difference (exhaust gas differential pressure between the inlet side and the outlet side) between the exhaust upstream side and the exhaust downstream side of the filter in the DPF 4. The DPF differential pressure sensor 4b is for detecting the degree of filter clogging in the DPF 4.

  The engine controller 5 is an ECU (Engine Control Unit) that controls the operation of the controller 6 based on the exhaust temperature detected by the exhaust temperature sensor 4a and the differential pressure detected by the DPF differential pressure sensor 4b. The engine controller 5 is a computer device having a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and the like. The engine controller 5 also controls the operation of the engine 2 and the common rail 3.

  In the present embodiment, the engine controller 5 and a controller 6 described later are collectively referred to as a control unit 7. That is, the control unit 7 controls various operations of the work vehicle 1. The control logic of the control unit 7 will be described later.

  The controller 6 is based on an instruction from the engine controller 5 and an electric signal sent from the operation state detection means 21a, 22a, 24a, that is, a signal indicating whether or not the operation levers 21, 22, 24 are operated. This is a computer device for controlling the operation of the electromagnetic solenoid 11c. The controller 6 has a CPU, RAM, ROM and the like.

  The lift cylinder 8 is a hydraulic actuator that raises and lowers a bucket (not shown), which is a work machine connected to the work vehicle 1 so as to be able to move up and down, with respect to the work vehicle 1. The bucket cylinder 9 is a hydraulic actuator that tilts a bucket (not shown) that is a working machine connected to the work vehicle 1 so as to be tiltable with respect to the work vehicle 1. The PTO 23 is a hydraulic pressure takeout circuit that attaches a separate attachment (a drill, a snow remover, a mower, etc .: not shown) that is a working machine other than the lift cylinder 8 and the bucket cylinder 9 and drives them.

  The hydraulic control valve 10 is a valve that controls the operation of an attachment or the like connected to the lift cylinder 8, the bucket cylinder 9, or the PTO 23, that is, a valve that controls pressure oil to the attachment or the like connected to the lift cylinder 8, the bucket cylinder 9, or the PTO 23. Is a collection of The hydraulic control valve 10 supplies hydraulic oil supplied from the work machine pump 14 via the hydraulic pressure switching mechanism 11 (electromagnetic switching valve 11a) to an attachment or the like connected to the lift cylinder 8, the bucket cylinder 9, or the PTO 23. .

  The hydraulic pressure switching mechanism 11 supplies hydraulic oil supplied from the work machine pump 14 to the hydraulic pressure control valve 10 in a normal state, and to the oil cooler 17 through a hydraulic pressure relief valve 11b which is a hydraulic load means under a predetermined condition. It is a mechanism for guiding. The hydraulic switching mechanism 11 includes an electromagnetic switching valve 11a, a hydraulic relief valve 11b, and an electromagnetic solenoid 11c.

  The hydraulic load means is not limited to the hydraulic relief valve 11b. For example, a throttle valve, a pressure reducing valve, or the like can be used as long as it can convert hydraulic pressure into heat energy. Is the same.

  The electromagnetic switching valve 11a is a four-port two-position switching electromagnetic switching valve provided between the hydraulic control valve 10 and the work machine pump 14. The electromagnetic switching valve 11a can switch whether the hydraulic oil supplied from the work machine pump 14 is supplied to the hydraulic control valve 10 or the hydraulic relief valve 11b. That is, normally, the work machine pump 14 and the hydraulic control valve 10 are connected and switched under predetermined conditions, and the work machine pump 14 and the hydraulic relief valve 11b are connected. The electromagnetic switching valve 11 a is switched and driven by excitation of an electromagnetic solenoid 11 c based on control information from the controller 6.

  The hydraulic relief valve 11 b is a high-pressure relief valve that guides hydraulic oil to the oil cooler 17 when the hydraulic pressure of the hydraulic oil supplied from the work machine pump 14 becomes a pressure equal to or higher than a set value. The electromagnetic solenoid 11c is excited based on control information from the controller 6, and switches the electromagnetic switching valve 11a.

  The operation lever 21 is an operation lever for driving the lift cylinder 8 to extend and contract. The operation state detection means 21a is means for detecting whether or not the operation lever 21 is operated, for example, a potentiometer. A detection signal from the operation state detection means 21a is sent to the controller 6.

  The operation lever 22 is an operation lever for driving the bucket cylinder 9 to extend and contract. The operation state detection means 22a is means for detecting whether or not the operation lever 22 is operated, for example, a potentiometer. A detection signal from the operation state detection means 22a is sent to the controller 6.

  The operation lever 24 is an operation lever for driving an attachment or the like connected to the PTO 23. The operation state detection means 24a is means for detecting whether or not the operation lever 24 is operated, for example, a potentiometer. A detection signal from the operation state detection unit 24 a is sent to the controller 6.

  The exhaust throttle 31 is a device that is disposed on the exhaust path of the engine 2 between the engine 2 and the DPF 4 and controls the flow rate of the exhaust discharged from the engine 2 to the DPF 4. The opening / closing operation of the exhaust throttle 31 is controlled by the engine controller 5.

  With the configuration described above, the hydraulic pressure switching mechanism 11 supplies the hydraulic oil supplied from the work machine pump 14 to the hydraulic control valve 10 in a normal state, and the oil cooler 17 via the hydraulic relief valve 11b under a predetermined condition. Lead to.

  Note that when the hydraulic relief valve 11 b is operated to guide the hydraulic oil to the oil cooler 17, an extra load is applied to the engine 2. Since this extra load does not directly contribute to the operation of the work machine mounted on the work vehicle 1, it can be said to be a dummy load. Therefore, even if the engine load factor of the engine 2 does not increase, the electromagnetic switching valve 11a is switched and the hydraulic relief valve 11b is operated to apply a dummy load to the engine 2. The engine load factor and the exhaust temperature can be forcibly increased, so that the DPF 4 can be stably regenerated. In other words, the hydraulic pressure switching mechanism 11 is intended to reach the self-regeneration temperature of the DPF 4 and applies a hydraulic load as auxiliary regeneration of the DPF 4, so to speak, it is a mechanism for increasing the engine load factor of the engine 2.

  In order to prevent the engine 2 from being stalled due to the application of such a dummy load, when the engine load factor exceeds a predetermined value, the electromagnetic switching valve 11a is returned to its original position and the hydraulic relief valve 11b is operated. Is preferably stopped.

  The HST pump 12 is rotationally driven by the engine 2 and supplies hydraulic oil for driving the HST motor 13 to the HST motor 13. The HST motor 13 is rotationally driven by the hydraulic pressure of the hydraulic oil supplied from the HST pump 12 and drives a traveling wheel (not shown) of the work vehicle 1.

  The work machine pump 14 is provided coaxially with the HST pump 12 and is driven to rotate by the engine 2. The work machine pump 14 supplies the hydraulic oil stored in the oil tank 16 to the electromagnetic switching valve 11a. The charge pump 15 is provided coaxially with the HST pump 12 and is driven to rotate by the engine 2. The charge pump 15 performs an operation of supplying hydraulic oil stored in the oil tank 16 to the HST pump 12 and the HST motor 13 and switching the HST pump 12 forward and backward.

  The oil cooler 17 is a device that cools the hydraulic oil discharged from the hydraulic relief valve 11b toward the oil tank 18. The electric fan 19 is provided in the vicinity of the oil cooler 17 such that the oil cooler 17 is sandwiched between the electric fan 19 and the cabin 20 of the work vehicle 1. The electric fan 19 is a device that blows air toward the oil cooler 17, that is, blows warm air heated by the heat of the hydraulic oil passing through the oil cooler 17 toward the cabin 20. The operation of the electric fan 19 is controlled by the control unit 7.

  With the configuration described above, in the work vehicle 1 according to the first embodiment, when the control unit 7 has a low regeneration load effect of the DPF 4 because the engine load factor of the engine 2 is low, the electromagnetic switching valve 11a. Is switched to guide the hydraulic oil to the oil cooler 17 through the hydraulic relief valve 11b. Thereby, by raising the engine load factor of the engine 2, the exhaust temperature of the DPF 4 is raised, and the DPF 4 can be regenerated.

  When the work vehicle 1 is stopped, as described above, the hydraulic pressure relief valve 11b is operated to assist regeneration of the DPF 4, and the engine load factor of the engine 2 is increased, and the work machine hydraulic system In order to apply a load to the engine, for example, by controlling the exhaust throttle 31 to be closed, it is possible to increase the rotational speed of the engine 2 and to regenerate the DPF 4.

  When the exhaust throttle 31 is closed, an extra load is applied to the engine 2. Since this extra load does not directly contribute to the operation of the work machine mounted on the work vehicle 1, it can be said to be a dummy load. Therefore, even if the engine load factor of the engine 2 does not increase, the engine load factor and the exhaust temperature of the engine 2 are forcibly increased by closing the exhaust throttle 31 and applying a dummy load to the engine 2. As a result, the DPF 4 can be stably regenerated. That is, closing the exhaust throttle 31 under a predetermined condition aims to reach the self-regeneration temperature of the DPF 4 and applies a hydraulic load as a regeneration aid for the DPF 4, so to speak, increases the engine load factor of the engine 2. Is.

  Another method for increasing the exhaust temperature of the DPF 4 by increasing the load applied to the engine for assisting regeneration of the DPF 4 is to control the exhaust throttle 31 to increase the exhaust back pressure. It is also possible to reduce the amount of air supplied to the cylinder, to perform post injection (additional injection after the combustion process), or to drive another load device such as a generator.

  Further, the control unit 7 switches and drives the electromagnetic switching valve 11 a and further operates the electric fan 19. By operating the electric fan 19, the heat of the hydraulic oil passing through the inside of the oil cooler 17, that is, warm air warmed by the heat generation energy generated in the hydraulic pressure relief valve 11 b, is blown into the cabin 20. Thereby, the heat generation energy can be reused as heat for heating in the cabin 20. The heat of the hydraulic oil passing through the oil cooler 17 may be used as a heat source for the heater in the cabin 20 by a method other than providing the electric fan 19 and operating it.

[Work vehicle operation example]
FIG. 2 is a flowchart showing an operation example of the work vehicle 1 according to the first embodiment of the present invention. The control unit 7 in FIG. 1 executes this control logic after the engine 2 is started.

First, in step S11, the control unit 7 obtains the actual exhaust temperature _{T E} and the set exhaust temperature _{T S} (S11). Here, the control unit 7 acquires the actual exhaust temperature T _E detected by the exhaust temperature sensor 4 a and the set exhaust temperature T _S set inside the control unit 7. The set exhaust temperature T _S referred to herein is a temperature required for regeneration control of the DPF 4.

Next, in step S12, the control unit 7 determines whether or not the actual exhaust temperature T _E is lower than the set exhaust temperature T _S (S12). If the actual exhaust gas temperature T _E is higher than the set exhaust temperature T _S (NO at S16), it is determined that stable on the regeneration control of DPF 4, the process ends.

On the other hand, when the actual exhaust temperature T _E is lower than the set exhaust temperature T _S (YES in S12), the control unit 7 proceeds to Step S13 and sets the duration time S _E and the set duration time S _S of the actual exhaust temperature T _E. Obtain (S13).

In step S <b> 13, the control unit 7 measures a continuation time S _E that indicates a time during which the actual exhaust temperature T _E has continued, and the measured continuation time S _E and a set continuation time set inside the control unit 7. S and _S are acquired. The set continuation time S _S here is the maximum allowable time in a state where the actual exhaust temperature T _E is lower than the set exhaust temperature T _S necessary for regeneration control of the DPF 4.

Thereafter, in step S14, the control unit 7 determines whether or not the duration time S _E is longer than the set duration time S _S (S14). If the duration time S _E is shorter than the set duration time S _S (NO in S14), it is determined that the regeneration control of the DPF 4 can be stably realized, and the process is terminated.

On the other hand, the control unit 7, (YES at S14) if the duration _{S E} is longer than the set duration _{S S,} i.e. the period of the actual exhaust gas temperature _{T E} is set exhaust temperature _{T S} from the low state to set the duration _{S S} When the condition of continuing only for the first time is satisfied, the process proceeds to step S15, and the engine load factor L and the set engine load factor Ls are acquired (S15).

  In step S <b> 15, the control unit 7 acquires a load factor L of the engine 2 and a set engine load factor Ls set inside the control unit 7. The set engine load factor Ls here is an engine load factor necessary for regeneration control of the DPF 4.

  Thereafter, in step S16, the control unit 7 determines whether or not the engine load factor L is lower than the set engine load factor Ls (S16). If the engine load factor L is higher than the set engine load factor Ls (NO in S16), it is determined that the regeneration control of the DPF 4 can be stably realized, and the process is terminated.

  On the other hand, when the engine load factor L is lower than the set engine load factor Ls (YES in S16), the control unit 7 proceeds to step S17.

In step S17, the control unit 7 acquires the DPF differential pressure Pf and the engine rotational speed Ns, together with these and engine load factor L is calculated PM deposition amount X, acquires the setting PM accumulation amount _{X S} (S17).

There is a specific relationship between the differential pressure upstream and downstream of the DPF 4 and the PM accumulation amount X in the DPF 4. Therefore, based on the differential pressure Pf detected by the DPF differential pressure sensor 4b, the engine rotation speed Ns, and the engine load factor L, the PM accumulation amount X in the DPF 4 can be calculated using a known method. Note that the set PM accumulation amount _{X S,} a PM deposition amount required regeneration control of DPF 4.

Next, in step S18, the control unit 7 determines whether the PM deposit amount X is greater than the set PM accumulation amount _{X S} (S18). When the PM accumulation amount X is less than the set PM accumulation amount _{X S} (NO at S18), it is determined that stable on the regeneration control of DPF 4, the process ends.

On the other hand, the control unit 7, when the PM deposition amount X is greater than the set PM accumulation amount _{X S} (YES at S18), the process proceeds to step S19, it acquires a duration M and set duration Ms of PM accumulation amount X ( S19).

In step S <b> 19, the duration M indicating the duration of the PM accumulation amount X is measured, and the measured duration M and the set duration Ms set inside the control unit 7 are acquired. The set duration Ms here is the maximum time allowed for state exceeds the set PM accumulation amount X _S of PM deposit amount X requires regeneration control of DPF 4.

  Thereafter, in step S20, the control unit 7 determines whether or not the duration M is longer than the set duration Ms (S20). If the duration M is shorter than the set duration Ms (NO in S20), it is determined that the regeneration control of the DPF 4 can be stably realized, and the process is terminated.

On the other hand, the control unit 7 continues when the duration M is longer than the set duration Ms (YES in S20), that is, the state where the PM accumulation amount X is larger than the set PM accumulation amount X _S for the set duration Ms. When the condition is satisfied, the process proceeds to step S21, and information indicating the operation state of the operation levers 21, 22, 24 is acquired by the operation state detection means 21a, 22a, 24a (S21).

  In step S21, the control unit 7 includes information indicating whether or not the operation lever 21 detected by the operation state detection unit 21a is operated, and whether or not the operation lever 22 detected by the operation state detection unit 22a is operated. And information indicating whether the operation lever 24 detected by the operation state detection unit 24a is operated, that is, information indicating whether a bucket or the like is operated.

  The information indicating whether or not the operation lever 21 is operated is paraphrased as information indicating whether or not a lift arm (not shown in FIG. 1) that is operated by the operation of the lift cylinder 8 of FIG. 1 is operated. be able to. The information indicating whether or not the operation lever 22 is operated is paraphrased as information indicating whether or not a bucket (not shown in FIG. 1) operated by the operation of the bucket cylinder 9 of FIG. 1 is operated. Can do. Further, the information indicating whether or not the operation lever 24 is operated refers to whether or not a working machine such as a drill (not shown in FIG. 1) operated by an operation of an attachment or the like connected to the PTO 23 of FIG. It can be paraphrased as information indicating that.

  Thereafter, in step S22, the control unit 7 determines whether or not the operation levers 21, 22, and 24 are operated based on the information acquired in step S21 (S22). When at least one of the operation levers 21, 22, and 24 is operated (NO in S22), it is determined that there is no need to operate the hydraulic relief valve 11b, and the process is terminated.

  On the other hand, if none of the operation levers 21, 22, 24 is operated (YES in S22), the control unit 7 proceeds to step S23 and drives the hydraulic relief valve 11b and the electric fan 19 (S23). In step S23, the control unit 7 switches the electromagnetic switching valve 11a by exciting the electromagnetic solenoid 11c, and operates the hydraulic relief valve 11b. Thus, a large amount of hydraulic oil is guided to the oil cooler 17 via the hydraulic relief valve 11b, whereby the engine load factor of the engine 2 is increased and the DPF 4 can be regenerated. Further, by operating the electric fan 19 to blow the heat of the hydraulic oil passing through the inside of the oil cooler 17, that is, warm air heated by the heat generation energy generated in the hydraulic pressure relief valve 11 b, toward the cabin 20, The heat generation energy is reused as heat for heating in the cabin 20.

As described above, according to the work vehicle 1 according to the first embodiment of the present invention, the control unit 7 performs control using the actual exhaust temperature T _E , the engine load factor L, and the PM accumulation amount X as parameters, When the levers 21, 22, 24 are not operated (including the case where the operation levers 21, 22, 24 are in the neutral position), the hydraulic pressure relief valve 11 b is operated to assist the regeneration of the DPF 4 to relieve the hydraulic pressure. Automatic control is performed. Thereby, stable and continuous regeneration control of the DPF 4 becomes possible. In addition, the frequency of regeneration of the DPF 4 performed while the work vehicle 1 itself is stopped, that is, the frequency of regeneration of the stationery is reduced, the work performed by the work vehicle 1 can be performed continuously, and the filter in the DPF 4 is extended in life. Can be made.

Also, if the actual exhaust temperature _{T E} is lower than the set exhaust temperature _{T S} satisfies the condition that continues for a period of set duration _{S S} (YES YES and in step S14 in step S12), the engine load factor L is is lower than the set engine load factor Ls (YES at S16), if the state PM deposit amount X is larger than the set PM accumulation amount _{X S} satisfies the condition that continues for a period of set duration Ms (YES in step S18 And only when the operation levers 21, 22, and 24 are not operated (YES in S22), the electromagnetic switching valve 11a is switched and the hydraulic relief valve 11b is operated only when the operation levers 21, 22, and 24 are not operated (YES in S22). . Thereby, unnecessary operation | movement of the electromagnetic switching valve 11a can be avoided, and fuel consumption can be suppressed. Further, the heat generated by the regeneration assisting control of the DPF 4 can be regenerated as heating and effectively used by the air blow by the electric fan 19.

  For example, when the engine load factor L is low in an idle state, or when the rotational speed of the engine 2 is in an engine rotational speed region in which the self-regeneration of the DPF 4 cannot be expected only by the operation of the hydraulic relief valve 11b, The hydraulic relief valve 11b may not be operated. In step S23, the heat of the hydraulic oil passing through the oil cooler 17 may be used as a heat source for the heater in the cabin 20 by a method other than operating the electric fan 19.

  Further, when the work vehicle 1 is stopped, it is desirable to increase the idle rotation speed of the engine 2. This is due to the following reason. That is, when the work vehicle 1 is stopped, the rotational speed of the engine 2 is considered to be low idle. Therefore, when the engine load factor of the engine 2 increases due to the operation of the hydraulic relief valve 11b, only the load increases while the rotational speed of the engine 2 remains low. However, this not only causes unpleasant vibration, but also makes it difficult to ensure the exhaust temperature.

  In addition, when the work vehicle 1 is stopped, the exhaust throttle 31 is operated together with the method of operating the hydraulic relief valve 11b to assist regeneration of the DPF 4 and increasing the engine load factor of the engine 2 as described above. Control to increase exhaust back pressure, throttle the amount of air supplied to the engine 2, perform post injection (additional injection after the combustion process), and drive another load device such as a generator By doing so, the exhaust temperature of the DPF 4 can be raised.

  Hereinafter, a second embodiment of the present invention will be described.

  In the first embodiment described above, when the operation levers 21, 22, and 24 are not operated under a predetermined condition, a load is applied to the working machine hydraulic system (see the upper part of FIG. 1) such as the hydraulic pressure switching mechanism 11 to exhaust temperature. The form which raises was demonstrated. In the second embodiment, in addition to the first embodiment, the forward / backward changeover switch 32 (see FIGS. 1 and 3) of the traveling system is in a neutral state under a predetermined condition, and the parking brake switch 33 is A mode in which the exhaust temperature is increased by applying a load to the working machine hydraulic system such as the hydraulic pressure switching mechanism 11 in the operating state, that is, when the vehicle is not traveling, will be described.

[Work vehicle configuration]
FIG. 3 is a diagram illustrating a configuration example of the work vehicle 100 according to the second embodiment of the present invention. In the following description, the description of the same components as those described in the configuration of the first embodiment in FIG. 1 will be omitted as appropriate.

  The work vehicle 100 according to the second embodiment has a configuration in which the work vehicle 1 according to the first embodiment further includes a forward / reverse switching switch 32, a parking brake switch 33, and the like. Hereinafter, each component will be described.

  The forward / reverse switching switch 32 is a switch for inputting an operation instruction related to forward / neutral (synonymous with neutral) / reverse of the work vehicle 100. The engine controller 5 acquires operation instruction information indicating whether or not neutral is input to the forward / reverse selector switch 32. A forward / reverse switching valve 44 (to be described later) switches forward / reverse according to a forward or reverse operation instruction input to the forward / reverse switching switch 32.

  The parking brake switch 33 is a switch that opens and closes in response to an operation on a parking brake (not shown) provided in the work vehicle 100. Specifically, it closes when the parking brake is operated (a state where the parking brake is effective), and opens when the parking brake is not operated.

  Subsequently, supplementary explanation will be given for the other components shown in FIG.

  The charge filter 41 is a filter for removing foreign matter. The relief valve 42 is a bypass valve for bypassing hydraulic oil flowing through the charge filter 41. The relief valve 42 is provided to prevent oil leakage due to case rupture or the like of the charge filter 41 when the charge filter 41 is clogged and the circuit pressure increases. The charge filter 41 and the relief valve 42 have an integral structure.

  The proportional pressure reducing valve 43 senses the flow rate of the charge pump 15 (proportional to the engine speed) and controls the circuit pressure. Specifically, the mechanical pressure reducing valve increases the circuit pressure as the engine speed increases. It is. The hydraulic oil whose pressure is reduced to a predetermined control pressure by the proportional pressure reducing valve 43 is guided to the actuator 48 via the forward / reverse switching valve 44 to control the tilting amount of the swash plate 12a of the HST pump 12. Thereby, the discharge flow rate of the HST pump 12 and the vehicle speed of the work vehicle 100 are controlled.

  Specific control of the proportional pressure reducing valve 43 is performed by an inching pedal 60 connected to an inching valve 50 which is an on-off valve that forms part of the proportional pressure reducing valve 43. The proportional pressure reducing valve 43 opens when the inching pedal 60 is depressed, The working vehicle 100 is decelerated by flowing pressure oil from the hydraulic circuit X or the like to the oil tank 16.

  The forward / reverse switching valve 44 is a switching valve for switching forward / reverse of the work vehicle 100. The forward / reverse switching valve 44 operates based on an electrical signal generated by pressing the forward / reverse switching switch 32, switches the direction of the control pressure of the hydraulic oil flowing through the hydraulic circuit X, and The tilting direction of the plate 12a, that is, the pressing direction of the actuator 48 is switched. Thereby, the rotation direction of the HST motor 13 is switched, and the forward / reverse movement of the work vehicle 100 is switched.

  The high pressure relief valves 45 and 46 are relief valves for controlling the maximum pressure in the hydraulic circuit X. The low pressure relief valve 47 is a relief valve for maintaining a constant pressure when the hydraulic oil in the hydraulic circuit X is insufficient and needs to be replenished.

  The actuator 48 is a servo cylinder that uses hydraulic oil flowing through the hydraulic circuit X to control forward / reverse switching and the angle of the swash plate 12 a of the HST pump 12.

  The low pressure relief valve 49 is a relief valve for controlling the internal pressure of a case (not shown) in which the HST pump 12 and the like are accommodated. When the internal pressure of the case becomes a certain value or more, the hydraulic oil is released from the low pressure relief valve 49 to the tank.

  The hydraulic circuit X is a circuit that controls the hydraulic oil supply path between the charge pump 15 and the swash plate 12 a of the HST pump 12, that is, the discharge flow rate of the HST pump 12. On the other hand, the hydraulic circuit Y is a closed hydraulic circuit between the HST pump 12 and the HST motor 13.

  The engine controller 5 detects the differential pressure detected by the DPF differential pressure sensor 4b, the exhaust temperature detected by the exhaust temperature sensor 4a, the operation input instruction input to the forward / reverse switching switch 32, and the parking brake switch 33. Based on the open / close state, the operation of the controller 6, the exhaust throttle 31 and the inching valve 50 is controlled.

  The HST pump 12 is rotationally driven by the engine 2 and supplies hydraulic oil for driving the HST motor 13 to the HST motor 13 via the hydraulic circuit Y.

  The charge pump 15 first causes the hydraulic oil stored in the oil tank 16 to flow through the charge filter 41 and the proportional pressure reducing valve 43, and then passes through the hydraulic pressure circuit X passing from the proportional pressure reducing valve 43 to the forward / reverse switching valve 44 and the actuator 48. Then, an operation of supplying the swash plate 12a of the HST pump 12 and an operation of supplying the hydraulic circuit Y via the high pressure relief valves 45 and 46 are performed.

  With the configuration described above, in the work vehicle 100 according to the second embodiment, the control unit 7 has insufficient regeneration control of the DPF 4 because the engine load factor of the engine 2 is low, and the forward / reverse selector switch 32 is In the neutral state (and the parking brake switch 33 is in an on state (open)), that is, when the vehicle is not running, the electromagnetic switching valve 11a is switched and oil is supplied via the hydraulic relief valve 11b. The hydraulic oil is guided to the cooler 17. As a result, the engine load factor of the engine 2 is increased and the DPF 4 can be regenerated.

  Further, in the work vehicle 100 according to the second embodiment, since the work vehicle 1 according to the first embodiment described above is in the same mode as when the vehicle is stopped, the hydraulic relief valve 11b is operated to assist regeneration of the DPF 4. In order to increase the engine load factor of the engine 2 and to apply a load to the working machine hydraulic system, for example, by controlling the exhaust throttle 31 to increase the rotational speed of the engine 2 and regenerate the DPF 4 Can also be possible.

  When the exhaust throttle 31 is closed, an extra load is applied to the engine 2. Since the extra load does not directly contribute to the operation of the work machine mounted on the work vehicle 100, it can be said to be a dummy load. Therefore, even if the engine load factor of the engine 2 does not increase, the engine load factor and the exhaust temperature of the engine 2 are forcibly increased by closing the exhaust throttle 31 and applying a dummy load to the engine 2. As a result, stable regeneration control of the DPF 4 becomes possible. That is, closing the exhaust throttle 31 under a predetermined condition aims to reach the self-regeneration temperature of the DPF 4 and applies a hydraulic load as a regeneration aid for the DPF 4, so to speak, increases the engine load factor of the engine 2. Is.

  Another method for increasing the exhaust temperature of the DPF 4 by increasing the load applied to the engine for assisting regeneration of the DPF 4 is to control the exhaust throttle 31 to increase the exhaust back pressure. It is also possible to reduce the amount of air supplied to the cylinder, to perform post injection (additional injection after the combustion process), or to drive another load device such as a generator.

  Further, the control unit 7 switches and drives the electromagnetic switching valve 11 a and further operates the electric fan 19. By operating the electric fan 19, the heat of the hydraulic oil passing through the inside of the oil cooler 17, that is, warm air warmed by the heat generation energy generated in the hydraulic pressure relief valve 11 b, is blown into the cabin 20. Thereby, the heat generation energy can be reused as heat for heating in the cabin 20. The heat of the hydraulic oil passing through the oil cooler 17 may be used as a heat source for the heater in the cabin 20 by a method other than providing the electric fan 19 and operating it.

[Work vehicle operation example]
FIG. 4 is a flowchart showing an operation example of the work vehicle according to the second embodiment of the present invention. In the work vehicle 100, the control logic is executed after the engine 2 is started.

In step S31 (steps S11 to S22), the state where the actual exhaust temperature T _E is lower than the set exhaust temperature T _S continues for the set duration S _S , the engine load factor L is lower than the set engine load factor Ls, continued state PM deposit amount X is larger than the set PM accumulation amount _{X S} only period set duration Ms, and, when the condition is met that the operation lever 21, 22, and 24 is not operated (YES in step S12 YES in step S14, YES in step S16, YES in step S18, YES in step S20, and YES in step S22), the process proceeds to step S32.

  On the other hand, if NO in step S31 (when all of steps S12, S14, S16, S18, S20, and S22 are not YES), it is determined that the regeneration control of DPF 4 can be stably realized, and the process is terminated. To do.

  When the process proceeds to step S32, the control unit 7 acquires the states of the forward / reverse switching switch 32 and the parking brake switch 33 (S32).

  Thereafter, in step S33, the control unit 7 determines whether or not a predetermined time has elapsed with the forward / reverse switching switch 32 acquired in step S32 in the neutral state and the parking brake switch 33 closed ( S33). The certain time here is preferably about 5 to 10 seconds.

  Here, when the forward / reverse selector switch 32 is not in the neutral state, or when the parking brake switch 33 is open, or when the forward / reverse selector switch 32 is in the neutral state (and the parking brake switch 33 is Even if it is in the closed state), if it does not continue for a certain period of time (NO in S33), the control unit 7 determines that the traveling system is not in the neutral state or that the work vehicle 100 is not stopped, and performs processing. finish.

  On the other hand, if the forward / backward changeover switch 32 is in the neutral state and the parking brake switch 33 is closed and the fixed time has elapsed (YES in S33), the control unit 7 proceeds to Step S34 and proceeds to the hydraulic relief valve 11b. Then, the electric fan 19 is driven (S34). In step S34, the control unit 7 switches the electromagnetic switching valve 11a by exciting the electromagnetic solenoid 11c and operates the hydraulic relief valve 11b. Thus, a large amount of hydraulic oil is guided to the oil cooler 17 via the hydraulic relief valve 11b, whereby the engine load factor of the engine 2 is increased and the DPF 4 can be regenerated. Further, by operating the electric fan 19 to blow the heat of the hydraulic oil passing through the inside of the oil cooler 17, that is, warm air heated by the heat generation energy generated in the hydraulic pressure relief valve 11 b, toward the cabin 20, The heat generation energy is reused as heat for heating in the cabin 20.

As described above, according to the work vehicle 100 according to the second embodiment of the present invention, the control unit 7 includes the actual exhaust temperature T _E , the engine load factor L, the PM accumulation amount X, the operation levers 21, 22, and 24. When the control is performed using the operation state as a parameter and the forward / reverse selector switch 32 is in the neutral state and the parking brake switch 33 is closed, that is, when the work vehicle 100 is stopped. In order to assist regeneration of the DPF 4, automatic control is performed to operate the hydraulic relief valve 11b to relieve the hydraulic pressure. Thereby, stable and continuous regeneration control of the DPF 4 becomes possible. Further, the frequency of regeneration of the DPF 4 performed while the work vehicle 100 itself is stopped, that is, the frequency of stationery regeneration is reduced, so that the work performed by the work vehicle 1 can be performed continuously, and the filter in the DPF 4 is extended in life. Can be made.

If YES in step S31, that is, if the condition that the actual exhaust temperature T _E is lower than the set exhaust temperature T _S continues for the set duration S _S (YES in step S12 and step S14). conditions in YES), if the engine load factor L is lower than the set engine load factor Ls (at S16 YES), that states the PM accumulation amount X is larger than the set PM accumulation amount _{X S} continues for a period of set duration Ms (YES in step S18 and YES in step S20), when any of the operating levers 21, 22, 24 is not operated (YES in S22), and when the forward / reverse selector switch 32 is in the neutral state, And only when the parking brake switch 33 is closed and a certain time has elapsed (YES in S33). The electromagnetic switching valve 11a is switched and the hydraulic relief valve 11b is operated. Thereby, unnecessary operation | movement of the electromagnetic switching valve 11a can be avoided, and fuel consumption can be suppressed. Further, the heat generated by the regeneration assisting control of the DPF 4 can be regenerated as heating and effectively used by the air blow by the electric fan 19.

  For example, when the engine load factor L is low in an idle state, or when the rotational speed of the engine 2 is in an engine rotational speed region in which the self-regeneration of the DPF 4 cannot be expected only by the operation of the hydraulic relief valve 11b, The hydraulic relief valve 11b may not be operated. In step S34, the heat of the hydraulic oil passing through the oil cooler 17 may be used as a heat source for the heater in the cabin 20 by a method other than operating the electric fan 19.

  Further, since the operation of the work vehicle 100 according to the second embodiment is assumed to be stopped, it is desirable to increase the idle rotation speed of the engine 2. This is due to the following reason. That is, when the work vehicle 100 is stopped, the rotational speed of the engine 2 is considered to be low idle. Therefore, when the engine load factor of the engine 2 increases due to the operation of the hydraulic relief valve 11b, only the load increases while the rotational speed of the engine 2 remains low. However, this not only causes unpleasant vibration, but also makes it difficult to ensure the exhaust temperature.

  Since the work vehicle 100 is stopped, as described above, the hydraulic relief valve 11b is operated to assist regeneration of the DPF 4 and the engine load factor of the engine 2 is increased, and the exhaust throttle 31 is controlled to control the exhaust. Increase back pressure, reduce the amount of air supplied to the engine 2, perform post injection (additional injection after the combustion process), and drive another load device such as a generator. As a result, the exhaust temperature of the DPF 4 can be increased.

FIG. 5 is a diagram for supplementary explanation of an operation example of the work vehicle according to the second embodiment of the present invention. In FIG. 5, the vertical axis represents the control pressure (unit: Pa), and the horizontal axis represents the rotational speed (unit: min ⁻¹ ) of the engine 2. The control pressure is a pressure for controlling the amount of tilt of the swash plate 12a of the HST pump 12.

A line segment L1 shown in FIG. 5 is a line segment showing the relationship between the pressure in the normal state and the rotational speed of the engine 2. In line L1, it is assumed rotational speed R ₁₁ of the engine 2 when the pressure is P ₁ is a starting rotational speed. That is, when the actual rotational speed of the engine 2 becomes larger than the starting speed R _11, the work vehicle 100 starts moving. Then, the rotational speed R ₁₂ of the engine 2 in the figure indicates the rotation speed during idling, the rotational speed R ₁₃ represents a rotational speed at idle when increasing the rotational speed by the operation control according to this embodiment.

4 is executed, on the assumption that the accelerator pedal (not shown) of the work vehicle 100 is not depressed, the forward / reverse selector switch 32 is in the forward / reverse state and the operation levers 21, 22, 24 are because, for example to shift the state of being operated, when the control shown in FIG. 4 is released, for the rotational speed R ₁₃ of the elevated engine 2 is larger than the starting speed R _11, the working vehicle 100 start・ Problems that cause sudden acceleration may occur.

Therefore, during the execution of the process related to step S34 in FIG. 4, the pressure of the inching valve 50 is reduced to shift the relationship between the pressure and the rotational speed of the engine 2 to the state of the line segment L2 in FIG. Then, even if the control shown in FIG. 4 is released, the rotational speed R ₁₃ of the elevated engine 2 than the starting rotational speed R ₁₄ of the engine 2 when the pressure in the line segment L2 is P ₁ Since it is small, the work vehicle 100 will not start or suddenly accelerate.

FIG. 6 is a diagram for explaining the effect of the work vehicle according to the second embodiment of the present invention. In FIG. 6, the vertical axis represents torque (unit: N · m), and the horizontal axis represents the rotational speed (unit: min ⁻¹ ) of the engine 2.

  A line segment L shown in FIG. 6 is a line segment showing the relationship between the torque and the rotational speed of the engine 2 at a temperature at which the DPF 4 can be regenerated (for example, 250 ° C. in the case of the exhaust upstream side of the DPF 4). That is, when the actual torque value and the rotational speed value of the engine 2 are included in the region (regeneration region) above the line segment L, regeneration control of the DPF 4 is possible. On the other hand, when the actual torque value and the rotation speed value of the engine 2 are included in the region (non-regeneration region) below the line segment L, regeneration control of the DPF 4 cannot be performed.

When step S16 in step S31 in FIG. 4 is YES, that is, the case where the engine load factor L is low is, for example, the case of point A in FIG. 6 (the rotational speed of the engine 2 is R ₁ ). This is a case where the vehicle 100 is not running and the work implement is not operated. The work performed by the work vehicle 100 in a state where the engine load factor L is low is a work in a low rotation range such as a work at substantially an idling rotational speed. In this case, since the region is below the line segment L, regeneration control of the DPF 4 cannot be performed.

Therefore, as shown in step S34 of FIG. 4, first, the idle rotational speed is increased to shift from the point A to the point B (the rotational speed of the engine 2 is R ₂ > R ₁ ). Next, the exhaust throttle 31 is closed and a load is applied to the work implement hydraulic system, thereby shifting from the point B to the point C state.

  As a result, the actual torque value and the rotational speed value of the engine 2 are located in a region above the line segment L, and stable and continuous regeneration control of the DPF 4 is possible. Further, the frequency of regeneration of the DPF 4 performed while the work vehicle 100 itself is stopped, that is, the regeneration of the stationery is reduced, the work performed by the work vehicle 100 can be continuously performed, and the filter in the DPF 4 is extended in life. Can be made.

  Further, as shown in step S34 of FIG. 4, by increasing the idle rotation speed and applying a load to the work implement hydraulic system, unpleasant vibration that may occur when only the load is applied is prevented, and the DPF 4 An exhaust temperature sufficient for regeneration can be secured.

  In addition, when the idle rotation speed is increased, in the work vehicle 100 equipped with the automotive HST, it is the same as that the accelerator is stepped on, so that the vehicle starts or suddenly accelerates as the idle rotation speed increases. May occur. However, such a problem can be prevented and safety can be ensured by increasing the idle rotation speed only when the forward / reverse selector switch 32 is neutral and the parking brake switch 33 is closed.

  The operation example of the work vehicle 100 according to the second embodiment of the present invention has been described above with reference to FIGS. 3 to 6. Hereinafter, control logic for canceling the above operation during execution will be described. .

[Control logic for work vehicle operation release]
FIG. 7 is a flowchart showing the control logic for releasing the operation of the work vehicle according to the second embodiment of the present invention. In the work vehicle 100, this control logic is executed during the execution of the operation shown in step S34 of FIG.

  First, in step S51, the control unit 7 detects that the forward / reverse switching switch 32 and the parking brake switch 33 are operated (S51). Here, the control unit 7 acquires the states of the forward / reverse switching switch 32 and the parking brake switch 33, the parking brake switch 33 is open, and the forward / reverse switching switch 32 is in the neutral state. When the state is switched to the forward / backward state (YES in S51), the process proceeds to the next step S52.

  Next, in step S52, the control unit 7 waits until the rotational speed of the engine 2 becomes normal low idle (S52). The normal low idle is a low idle rotational speed before the idle rotational speed is increased by the process of step S34 in FIG. In step S52, the control unit 7 stops the increase in the idle rotation speed according to step S34 in FIG.

  When the rotational speed of the engine 2 becomes normal low idle (YES in S52), the control unit 7 outputs a valve control output signal for driving the forward / reverse switching valve 44 (S53). Thereafter, the forward / reverse switching valve 44 is driven based on the valve control output signal, and returns to the normal state before the execution of step S34 in FIG.

  With the process described above, the work vehicle 100 according to the second embodiment of the present invention cancels the operation shown in Step S34 of FIG. 4 and returns to the normal state. The effect of this operation will be described below. When the forward / reverse switching switch 32 is operated without driving this control logic and the forward / reverse switching valve 44 is driven immediately, the forward / reverse switching valve 44 is not changed until the rotational speed of the engine 2 has been reduced to low idle. Therefore, when the travel pedal (not shown) is not depressed (when it is intended to stop), there is a possibility that a problem of starting for a moment may occur. However, such a problem can be prevented by waiting until the rotational speed of the engine 2 becomes low idle as in the present control logic.

  In step S52, a process of waiting until the rotation speed of the engine 2 becomes a normal low idle is performed, but this is not a limitation. For example, control may be performed so as to proceed to the next step S53 when a predetermined time has passed so that the rotation speed of the engine 2 becomes a normal low idle.

  Moreover, the process of step S51-S53 can be specifically comprised as follows. That is, when the engine controller 5 receives a signal indicating that the forward / reverse selector switch 32 has been operated (YES in S51), the signal is temporarily input to the controller 6. Then, the controller 6 can be configured to output a valve control output signal after detecting that the rotational speed of the engine 2 has decreased (YES in S52).

  Moreover, the process of step S51-S53 can be specifically comprised as follows. That is, when the engine controller 5 receives a signal indicating that the forward / reverse selector switch 32 has been operated (YES in S51), the signal is temporarily input to the controller 6. Then, the controller 6 transmits a control signal indicating whether or not to operate the delay means for delaying for a predetermined time to the engine controller 5, and the engine controller 5 is configured to drive the forward / reverse switching valve 44 with a delay for a predetermined time by the delay means. You can also

  Hereinafter, a third embodiment of the present invention will be described.

  In the first and second embodiments described above, when the operation levers 21, 22, 24 are not operated under a predetermined condition, or the traveling system forward / backward changeover switch 32 (see FIGS. 1 and 3) under a predetermined condition. ) Is in a neutral state, that is, when the vehicle is not running, etc., a mode in which a load is applied to the work machine hydraulic system (see the upper part of FIGS. 1 and 3) such as the hydraulic switching mechanism 11 to increase the exhaust temperature did. In the third embodiment, when the forward / backward changeover switch 32 (see FIG. 8) of the traveling system is in a forward or reverse state under a predetermined condition, that is, when traveling, the exhaust throttle 31 is controlled to control the exhaust back. A mode in which a load is applied to the engine 2 by increasing the pressure will be described.

[Work vehicle configuration]
FIG. 8 is a diagram illustrating a configuration example of the work vehicle 200 according to the third embodiment of the present invention. In the following description, the same components as those in FIG. 1 and FIG.

  The work vehicle 200 according to the third embodiment includes a proportional pressure reducing valve 43 (including an inching valve 50 and the like) in the work vehicles 1 and 100 according to the first and second embodiments shown in FIGS. 1 and 3. The configuration is replaced with 43A (including the inching valve 50 and the like). Hereinafter, each component will be described.

  The work vehicle 200 according to the third embodiment includes an exhaust throttle 31 having the same configuration as the work vehicles 1 and 100 according to the first and second embodiments, and the exhaust throttle 31 is mainly controlled by a plurality of means. Can be added.

  The work vehicle 200 has an electromagnetic solenoid 43B that can be hydraulically controlled under a predetermined condition in the electromagnetic proportional pressure reducing valve 43A, and is driven based on control information from the controller 6.

  Specific control of the normal (first and second embodiments) proportional pressure reducing valve 43 is performed by an inching pedal 60 connected to an inching valve 50 which is a proportional on-off valve forming a part of the proportional pressure reducing valve 43. The valve 43 is opened when the inching pedal 60 is depressed, and pressure oil is supplied from the hydraulic circuit X or the like to the oil tank 16 to decelerate the work vehicles 1 and 100.

  However, the electromagnetic proportional pressure reducing valve 43A of the work vehicle 200 according to the third embodiment decelerates the work vehicle 200 in response to the depression of the inching pedal 60 in a normal state, but the controller 6 gives an instruction according to a predetermined condition such as the engine speed. Is provided, and the vehicle is decelerated regardless of the depression of the inching pedal 60.

  With the configuration described above, in the work vehicle 200 according to the third embodiment, the control unit 7 has insufficient regeneration of the DPF 4 because the engine load factor of the engine 2 is low, and the forward / reverse selector switch 32 moves forward. Alternatively, when the vehicle is traveling in reverse, that is, while traveling, the exhaust throttle 31 is controlled to increase the exhaust back pressure, thereby applying a load to the engine 2 to enable regeneration control of the DPF 4.

  When the exhaust throttle 31 is closed, an extra load is applied to the engine 2. Since the extra load does not directly contribute to the operation of the work machine mounted on the work vehicle 200, it can be said to be a dummy load. Therefore, even if the engine load factor of the engine 2 does not increase, the engine load factor and the exhaust temperature of the engine 2 are forcibly increased by closing the exhaust throttle 31 and applying a dummy load to the engine 2. As a result, stable regeneration control of the DPF 4 becomes possible. That is, closing the exhaust throttle 31 under a predetermined condition aims to reach the self-regeneration temperature of the DPF 4 and applies a hydraulic load as a regeneration aid for the DPF 4, so to speak, increases the engine load factor of the engine 2. Is.

  Another method for increasing the exhaust temperature of the DPF 4 by increasing the load applied to the engine to assist regeneration of the DPF 4 is to control the exhaust throttle 31 to increase the exhaust back pressure and supply it to the engine 2. It is also possible to reduce the amount of air to be performed, to perform post injection (additional injection after the combustion process), or to drive another load device such as a generator.

  In a situation where the exhaust throttle 31 of the work vehicle 200 is controlled to increase the exhaust back pressure, it is desirable to increase the rotational speed of the engine 2. This is due to the following reason. That is, in order to increase the exhaust back pressure and raise the exhaust temperature while the work vehicle 200 is traveling, it is necessary to set the rotational speed of the engine 2 higher than usual.

  In this case, an increase in the rotational speed of the engine 2 may increase the speed of the work vehicle 200 more than necessary.

  Therefore, in the work vehicle 200 according to the third embodiment, when the rotational speed of the engine 2 exceeds a predetermined condition, the control unit 7 gives an instruction to the electromagnetic solenoid 43B of the electromagnetic proportional pressure reducing valve 43A, and the electromagnetic The proportional pressure reducing valve 43A is opened to control the tilting amount of the swash plate 12a of the HST pump 12 and to safely control the speed of the work vehicle 200. That is, it can serve as an engine brake.

  With this configuration, even when the exhaust throttle 31 is closed and the engine load factor L is increased, stable running can be maintained.

[Work vehicle operation example]
FIG. 9 is a flowchart showing an operation example of the work vehicle according to the third embodiment of the present invention. In the work vehicle 200, the control logic is executed after the engine 2 is started. Of the steps shown in FIG. 9, the same steps as those in FIGS. 2 and 4 are denoted by the same reference numerals and redundant description is omitted.

First, in step S31 (steps S11 to S22), the control unit 7 continues the state where the actual exhaust temperature T _E is lower than the set exhaust temperature T _S for the set duration S _S , and the engine load factor L is the set engine load. lower than the rate Ls, continued state PM deposit amount X is larger than the set PM accumulation amount X _S only period set duration Ms, and, satisfying the condition that the operation lever 21, 22, and 24 is not operated If (YES in step S12, YES in step S14, YES in step S16, YES in step S18, YES in step S20, and YES in step S22), the process proceeds to step S32, otherwise (steps S12, S14, Any of S16, S18, S20, and S22 is NO), and it is determined that the regeneration control of the DPF 4 can be realized stably. Then, the process ends.

  When the process proceeds to step S32, the control unit 7 acquires the states of the forward / reverse switching switch 32 and the parking brake switch 33 (S32).

  Thereafter, in step S41, the controller 7 determines whether or not the forward / reverse selector switch 32 is in the forward / reverse state (that is, not in the neutral state) and the parking brake switch 33 is in the open state (S41). ).

  When the forward / reverse selector switch 32 is in the forward / reverse state and the parking brake switch 33 is open (YES in S41), the process proceeds to step S42, and the control unit 7 performs control to close the exhaust throttle 31 ( S42).

  On the other hand, when the forward / reverse selector switch 32 is in the neutral state or the parking brake switch 33 is closed (NO in S41), the control unit 7 ends the process.

As described above, according to the work vehicle 200 according to the operation example, the control unit 7 uses the actual exhaust temperature T _E , the engine load factor L, the PM accumulation amount X, and the operation state of the operation levers 21, 22 and 24 as parameters. When the forward / backward changeover switch 32 is in the forward / backward state and the parking brake switch 33 is in the open state, that is, when the work vehicle 200 is running without operating the work implement. In order to assist regeneration of the DPF 4, control for closing the exhaust throttle 31 is performed. As a result, stable and continuous regeneration control of the DPF 4 can be performed without affecting the traveling of the work vehicle 200. Further, the frequency of regeneration of the DPF 4 performed while the work vehicle 200 itself is stopped, that is, the regeneration of the stationery is reduced, the work performed by the work vehicle 200 can be performed continuously, and the filter in the DPF 4 is extended in life. Can be made.

If YES in step S31, that is, if the condition that the actual exhaust temperature T _E is lower than the set exhaust temperature T _S continues for the set duration S _S (YES in step S12 and step S14). conditions in YES), if the engine load factor L is lower than the set engine load factor Ls (at S16 YES), that states the PM accumulation amount X is larger than the set PM accumulation amount _{X S} continues for a period of set duration Ms Is satisfied (YES in step S18 and YES in step S20), when none of the operation levers 21, 22, 24 is operated (YES in S22), and when the forward / reverse selector switch 32 is in the forward / reverse travel state. And, when the parking brake switch 33 is in the open state (YES in S41), the exhaust throttle 31 is operated. Yes. Thereby, an unnecessary operation | movement can be avoided and a fuel consumption can be suppressed.

  Further, when the rotational speed of the engine 2 exceeds a predetermined condition, the control unit 7 gives an instruction to the electromagnetic solenoid 43B of the electromagnetic proportional pressure reducing valve 43A, opens the electromagnetic proportional pressure reducing valve 43A, and the HST pump 12 In order to control the tilting amount of the swash plate 12a and decelerate the work vehicle 200, the work vehicle 200 travels downward on a steep slope or a gentle downhill without stepping on an accelerator pedal (not shown). You can drive safely even if you are.

  As another method for increasing the exhaust temperature of the DPF 4 by increasing the load applied to the engine for assisting regeneration of the DPF 4, the exhaust throttle 31 is controlled to increase the exhaust back pressure and supply to the engine 2. It is also possible to reduce the amount of air to be performed, to perform post injection (additional injection after the combustion process), or to drive another load device such as a generator.

  As mentioned above, although embodiment of this invention was described, the said embodiment showed one of the application examples of this invention, and in the meaning which limits the technical scope of this invention to the specific structure of the said embodiment. Absent. Various modifications can be made without departing from the scope of the present invention.

1 Working vehicle (first embodiment)
2 Engine 4 DPF (Exhaust gas purification device)
4a Exhaust temperature sensor 4b DPF differential pressure sensor 7 Control unit 8 Lift cylinder 9 Bucket cylinder 10 Hydraulic control valve 11 Hydraulic switching mechanism 11a Electromagnetic switching valve 11b Hydraulic load means (hydraulic relief valve)
11c Electromagnetic solenoid 14 Working machine pump 17 Oil cooler 19 Electric fan 20 Cabins 21, 22 Operation levers 21a, 22a Operation state detection means 23 PTO
31 Exhaust throttle 32 Forward / reverse selector switch 100 Work vehicle (second embodiment)
200 work vehicle (third embodiment)

Claims (5)

A work vehicle having an engine equipped with an exhaust purification device,
An exhaust temperature detector for detecting the exhaust temperature of the engine;
A differential pressure detector for detecting a differential pressure upstream and downstream of the exhaust gas of the exhaust gas purification device;
A hydraulic cylinder for operating a work machine mounted on the work vehicle;
A hydraulic control valve for controlling the operation of the hydraulic cylinder;
A work machine pump for supplying hydraulic oil to the hydraulic control valve;
An electromagnetic switching valve provided between the hydraulic control valve and the work machine pump, and capable of switching between supplying hydraulic oil to the hydraulic control valve or hydraulic load means;
An oil cooler for cooling the hydraulic oil discharged from the hydraulic load means;
A control unit for controlling various operations of the work vehicle,
The control unit acquires the engine load factor of the engine while the exhaust temperature and the differential pressure satisfy predetermined conditions, performs control based on the exhaust temperature, the differential pressure, and the engine load factor, and performs the work When the operation lever for operating the machine is not operated, the electromagnetic switching valve is switched and the hydraulic fluid is guided to the oil cooler through the hydraulic load means to reduce the load applied to the engine. A work vehicle characterized by being enlarged. Furthermore, an exhaust throttle provided between the engine and the exhaust purification device is provided,
The control unit increases the load applied to the engine by increasing the idle rotation speed of the engine and closing the exhaust throttle when the electromagnetic switching valve is switched. The work vehicle according to claim 1.   A forward / reverse switching switch for operating forward / neutral / reverse of the work vehicle is provided, and the control unit switches and drives the electromagnetic switching valve when an operation instruction related to neutral is input to the forward / backward switching switch, The work vehicle according to claim 1 or 2, wherein a load applied to the engine is increased by guiding the hydraulic oil to the oil cooler through a hydraulic load means.   The work vehicle according to any one of claims 1 to 3, wherein the heat of the hydraulic oil flowing through the oil cooler is used as a heat source of the heater. An electric fan that is provided near the oil cooler and blows air toward the oil cooler;
5. The work vehicle according to claim 1, wherein the control unit further operates the electric fan when the exhaust temperature and the differential pressure satisfy predetermined conditions. 6.

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