WO2019049427A1

WO2019049427A1 - Cabin vibration damping system for work vehicle

Info

Publication number: WO2019049427A1
Application number: PCT/JP2018/018603
Authority: WO
Inventors: 伊藤　達夫
Original assignee: Ｋｙｂ株式会社
Priority date: 2017-09-08
Filing date: 2018-05-14
Publication date: 2019-03-14
Also published as: JP2019048546A

Abstract

This cabin vibration damping system (100) comprises: a shock absorber (10) provided between the frame (2) and cabin (6) of a tractor (1) and able to freely change the damping force for damping the cabin (6) vibration; an acceleration sensor (62) for detecting at least the acceleration (α) of the cabin (6) in the vibration direction of the cabin (6); and a control device (60) for controlling the magnitude of the damping force to be generated by the shock absorber (10), on the basis of the acceleration (α) of the cabin (6) detected by the acceleration sensor (62) and resonance frequency (fm) of the cabin (6).

Description

Cabin damping system for work vehicle

The present invention relates to a cabin damping system that suppresses vibration of a cabin of a work vehicle.

JP 2010-260460 A discloses a work vehicle in which a cabin is installed on a frame via a coil spring and an oil damper. In this work vehicle, vibration of the cabin is suppressed by the coil spring and the oil damper.

In general, rough terrain such as a field where a work vehicle travels is more uneven compared to a paved surface, so to improve the operator's riding comfort, reduce the damping force of the damper and cause vibration from the frame to the cabin It is preferable not to transmit. On the other hand, when the cabin starts to vibrate at the resonance frequency due to an impact when riding up or down from a level difference etc., the vibration of the cabin can not be suppressed if the damping force of the damper is small. There is a risk of worsening the ride.

An object of the present invention is to accurately suppress vibration of a cabin of a work vehicle.

According to an aspect of the present invention, a cabin damping system for suppressing vibration of a cabin of a work vehicle is provided between a frame of the work vehicle and the cabin, and is capable of changing a damping force for damping the vibration. The buffer unit is generated based on the buffer unit, an acceleration detection unit that detects an acceleration of the cabin in at least the direction of the vibration, and the acceleration of the cabin detected by the acceleration detection unit and a resonance frequency of the cabin. And a controller configured to control the magnitude of the damping force.

FIG. 1 is a side view of a tractor to which a cabin damping system according to a first embodiment of the present invention is applied. FIG. 2 is a rear view of a tractor to which a cabin damping system according to a first embodiment of the present invention is applied, viewed from the rear. FIG. 3 is a hydraulic circuit diagram of the cabin damping system according to the first embodiment of the present invention. FIG. 4 is an enlarged view showing a buffer portion of the cabin damping system according to the first embodiment of the present invention. FIG. 5 is a flowchart of processing executed by the control unit of the cabin damping system according to the first embodiment of the present invention. FIG. 6 is a hydraulic circuit diagram of a cabin damping system according to a second embodiment of the present invention. FIG. 7 is a hydraulic circuit diagram of a cabin damping system according to a third embodiment of the present invention. FIG. 8 is an enlarged view showing a buffer portion of a cabin damping system according to a third embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

First Embodiment
A tractor 1 to which a cabin damping system 100 according to a first embodiment of the present invention is applied will be described with reference to FIGS. 1 and 2. FIG. 1 shows a side view of the tractor 1 and FIG. 2 shows a rear view of the tractor 1 viewed from the rear.

The tractor 1 shown in FIGS. 1 and 2 is a work vehicle that travels on uneven terrain such as a field. The tractor 1 includes a frame 2 extending in the front-rear direction of the vehicle, front wheels 3 and rear wheels 4 supported by the frame 2, and a cabin 6 installed on the frame 2 via hydraulic cylinders 20 described later. An engine (not shown) is mounted in front of the frame 2 and a bonnet 5 is attached to the frame 2 so as to cover the engine. The tractor 1 travels by the power of the engine being transmitted to the front wheels 3 and the rear wheels 4 via a gear case (not shown).

The cabin 6 is connected to the frame 2 on the front side of the vehicle via a pair of cylindrical rubber bush mounts 7 provided at both ends in the width direction of the vehicle. The rubber bush mount 7 is arranged such that its support shaft extends in the width direction of the vehicle. That is, as shown by arrow A in FIG. 1, the cabin 6 is supported swingably in the pitch direction of the vehicle centering on the rubber bush mount 7.

The cabin 6 and the frame 2 are connected via a hydraulic cylinder 20 provided in a pair in the width direction of the vehicle, and connected via a lateral rod 8 disposed so as to extend in the width direction of the vehicle. Therefore, although the cabin 6 is allowed to be displaced in the vertical direction of the vehicle with respect to the frame 2, the displacement in the width direction of the vehicle is limited.

Next, the cabin damping system 100 will be described with reference to FIGS. 3 and 4.

The cabin damping system 100 includes a buffer unit 10 that can change the damping force that attenuates the vibration of the cabin 6, a cabin height adjustment unit 50 that supplies and discharges hydraulic fluid as a working fluid to the buffer unit 10, and the buffer. And a controller 60 as a controller that controls the magnitude of the damping force generated by the unit 10.

The buffer unit 10 has a hydraulic cylinder 20 as a pair of hydraulic cylinders provided between the cabin 6 and the frame 2 respectively on the right side and the left side of the vehicle. Since the pair of hydraulic cylinders 20 have the same configuration, only one configuration will be described below.

The hydraulic cylinder 20 has a cylinder tube 21 whose one end is connected to the frame 2 and in which the hydraulic oil is sealed, and a piston side chamber 24 slidably disposed in the cylinder tube 21 and having a cylinder tube 21 as a first fluid chamber. And a piston 22 defined in a rod side chamber 25 as a second fluid chamber, and a piston rod 23 having one end coupled to the piston 22 and the other end coupled to the cabin 6.

The hydraulic cylinder 20 is a so-called single-acting hydraulic cylinder which is extended by the supply of hydraulic fluid to the piston side chamber 24 and is contracted by the discharge of hydraulic fluid from the piston side chamber 24. The hydraulic cylinder 20 is connected to the frame 2 at the base end of the cylinder tube 21 via the connecting portion 26 and is connected to the cabin 6 via the connecting portion 27 at the tip end of the piston rod 23.

Further, inside the piston 22 of the hydraulic cylinder 20, an expansion damping valve 29a and a compression damping valve 29b are provided.

The expansion damping valve 29a is provided in the communication passage 22a that connects the piston side chamber 24 and the rod side chamber 25. When the hydraulic cylinder 20 extends, the expansion side damping valve 29a opens to open the communication passage 22a and passes through the communication passage 22a. As a result, the flow of hydraulic fluid moving from the rod side chamber 25 to the piston side chamber 24 is resisted.

The pressure-side damping valve 29b is provided in the communication passage 22b that connects the piston side chamber 24 and the rod side chamber 25. When the hydraulic cylinder 20 contracts, it opens to open the communication passage 22b and passes through the communication passage 22b. This resists the flow of hydraulic fluid moving from the piston side chamber 24 to the rod side chamber 25.

The buffer unit 10 further includes a damping force switching valve 30 provided inside the piston rod 23, as shown in FIG.

The damping force switching valve 30 is an electromagnetic two-position switching valve provided on a communication passage 28 formed in a piston rod 23 that communicates the piston side chamber 24 and the rod side chamber 25. The damping force switching valve 30 is opposed to the solenoid 33 driven by the current supplied from the control device 60, the valve body 31 to which the biasing force of the solenoid 33 is applied via the transmission member 34, and the biasing force of the solenoid 33 And a spring 32 for applying a biasing force to the valve body 31.

The valve body 31 has a large flow passage area, a first position 31 a which hardly gives resistance to hydraulic oil flowing in the communication passage 28, and a small flow passage area, which applies relatively large resistance to hydraulic oil flowing in the communication passage 28. And 2 positions 31b.

The position of the valve body 31 is switched by the biasing force of the spring 32 and the biasing force of the solenoid 33. Specifically, in a state in which no current is applied to the solenoid 33, the biasing force of the spring 32 holds the first position 31a, and the current is applied to the solenoid 33 and applied to the valve body 31 via the transmission member 34. When the biasing force of the solenoid 33 exceeds the biasing force of the spring 32, the second position 31b is switched. The damping force switching valve 30 is configured such that the position of the valve body 31 is the second position 31b when no current is applied to the solenoid 33, and the first position 31a when the current is applied to the solenoid 33. It may be

When the position of the damping force switching valve 30 is at the first position 31a, when the hydraulic cylinder 20 expands and contracts, the hydraulic oil can move back and forth between the piston side chamber 24 and the rod side chamber 25 without a relative resistance. The resulting damping force is minimal. On the other hand, when the position of the damping force switching valve 30 is at the second position 31 b, when the hydraulic cylinder 20 expands and contracts, movement of hydraulic oil between the piston side chamber 24 and the rod side chamber 25 is restricted. The damping force that occurs is maximized.

Thus, the buffer unit 10 has a vibration damping function of damping vibration by generating damping force.

The buffer 10 further includes an accumulator 40 connected to the hydraulic cylinder 20 through the connection passage 42.

As shown in FIG. 3, the accumulator 40 internally includes an oil chamber 41 a connected to the piston side chamber 24 through the connection passage 42 and a spring chamber 41 b that applies pressure to the oil chamber 41 a.

The spring chamber 41b is a gas chamber in which a pressurized gas such as nitrogen is sealed, and a gas pressure is applied to a liquid surface which is a boundary surface with the oil chamber 41a. The free piston that divides the oil chamber 41a and the spring chamber 41b may be accommodated in the accumulator 40. Further, a free piston that divides the oil chamber 41a and the spring chamber 41b may be accommodated in the accumulator 40, and a metal spring may be accommodated in the spring chamber 41b. That is, instead of the pressurized gas, a pressure may be applied to the oil chamber 41a using a spring.

The characteristics of the accumulator 40 are set by adjusting the gas pressure in the spring chamber 41b, the volume of the accumulator 40, and the like.

Since the oil chamber 41a and the piston side chamber 24 are always in communication through the connection passage 42, the piston side chamber 24 is constantly pressurized by the pressure of the oil chamber 41a.

Here, the piston side chamber 24 connected to the oil chamber 41 a of the accumulator 40 is compressed as the load acting in the direction to contract the hydraulic cylinder 20 is larger. As the piston side chamber 24 is compressed, the hydraulic oil discharged from the cylinder tube 21 moves to the oil chamber 41 a through the connection passage 42 and increases the pressure in the spring chamber 41 b. The energy stored in the spring chamber 41 b in this manner is a restoring force that causes the piston side chamber 24 to expand. That is, as the accumulator 40 is connected, the piston side chamber 24 functions as a fluid spring that releases energy stored in compression as it is expanded.

Thus, the buffer unit 10 has a vibration damping function and also has a shock absorbing function of storing a shock as energy.

The cabin height adjustment unit 50 changes the relative distance between the frame 2 and the cabin 6 by supplying and discharging the working oil to the piston side chamber 24 of the hydraulic cylinder 20, and adjusts the height of the cabin 6 with respect to the traveling road surface It is a thing.

The cabin height adjustment unit 50 is provided with a hydraulic pump 51 for supplying hydraulic fluid, a direction switching valve 52 provided between the hydraulic pump 51 and the hydraulic cylinder 20 to switch the extension direction of the hydraulic cylinder 20, and the hydraulic cylinder 20. It has a tank T to which the hydraulic fluid to be discharged is introduced, and a supply / discharge passage 56 connecting the hydraulic cylinder 20 and the direction switching valve 52. In the cabin height adjustment unit 50, hydraulic fluid is used as the hydraulic fluid, but instead of hydraulic fluid, hydraulic fluid such as water-soluble alternative liquid may be used as the hydraulic fluid, or gas may be used. It may be used as a working fluid.

The hydraulic pump 51 is driven by an engine or an electric motor (not shown), and supplies hydraulic fluid stored in the tank T to the piston side chamber 24 of the hydraulic cylinder 20.

The direction switching valve 52 is an electromagnetic switching valve whose position is switched by the control device 60. The direction switching valve 52 supplies the hydraulic fluid to the hydraulic cylinder 20 and extends the hydraulic cylinder 20. The directional valve 52 discharges the hydraulic fluid from the hydraulic cylinder 20 There are three positions, a contraction position 52b for contracting the cylinder 20 and a stop position 52c for stopping the supply and discharge of hydraulic fluid to the hydraulic cylinder 20.

One end of the supply and discharge passage 56 is connected to the direction switching valve 52, and the other end is branched to be connected to a connection passage 42 that connects the piston side chamber 24 and the oil chamber 41a. An operation check valve 53 is interposed on the direction switching valve 52 side of the branch point of the supply and discharge passage 56.

The directional control valve 52 is connected to the supply / discharge passage 56 and also includes a supply passage 55 for guiding the hydraulic fluid discharged from the hydraulic pump 51, a discharge passage 57 for returning the hydraulic fluid to the tank T, and the operation check valve 53. An operating passage 59 communicating with the pilot pressure chamber is connected. The supply passage 55 and the discharge passage 57 are connected by a relief passage 58, and the relief passage 58 is provided with a relief valve 54 that opens when the hydraulic pressure of the supply passage 55 exceeds a set pressure.

When the direction switching valve 52 is switched to the extended position 52a, the discharge passage 57 and the operation passage 59 communicate with each other, and the supply and discharge passage 56 communicates with the supply passage 55. The hydraulic oil discharged from the hydraulic pump 51 flows into the piston side chambers 24 of the pair of hydraulic cylinders 20 through the supply passage 55 and the supply and discharge passage 56. As a result, the pair of hydraulic cylinders 20 are extended synchronously, the distance between the frame 2 and the cabin 6 is increased, and the height of the cabin 6 with respect to the traveling road surface is increased.

When the direction switching valve 52 is switched to the contracted position 52b, the supply passage 55 and the operation passage 59 communicate with each other, and the supply and discharge passage 56 communicates with the discharge passage 57. Since the hydraulic oil discharged from the hydraulic pump 51 is led as a pilot pressure to the operating check valve 53 via the operating passage 59, the operating check valve 53 is opened, and the hydraulic oil in the piston side chamber 24 is supplied and discharged 56, It is returned to the tank T through the discharge passage 57. As a result, the pair of hydraulic cylinders 20 contract in synchronization, and the distance between the frame 2 and the cabin 6 decreases, and the height of the cabin 6 with respect to the traveling road surface decreases.

When the directional control valve 52 is switched to the stop position 52c, the supply passage 55, the discharge passage 57, the operating passage 59, and the supply and discharge passage 56 all communicate. As a result, all the hydraulic oil supplied from the hydraulic pump 51 through the supply passage 55 is returned to the tank T. At this time, since the pressure in the operating passage 59 becomes equal to that in the tank T, the operating check valve 53 is closed by the biasing force of the spring. Thereby, the extension operation of the pair of hydraulic cylinders 20 is stopped, and the height of the cabin 6 with respect to the frame 2 is maintained.

In this manner, the height of the cabin 6 with respect to the frame 2, that is, the height of the cabin 6 with respect to the road surface can be adjusted by extending and retracting the hydraulic cylinder 20.

The cabin damping system 100 includes an acceleration sensor 62 as an acceleration detection unit for detecting an acceleration α of the cabin 6, a stroke sensor 64 as a distance detection unit for detecting a relative distance between the frame 2 and the cabin 6, and And a tilt sensor 66 as a tilt detection unit that detects a tilt degree.

The acceleration sensor 62 is attached to the cabin 6 and detects an acceleration α of the cabin 6 in the vibration direction of the cabin, that is, the vertical direction of the cabin 6 or the direction in which the hydraulic cylinder 20 extends and contracts. The acceleration α detected by the acceleration sensor 62 is input to the control device 60. Since the cabin 6 swings in the pitch direction, the direction of the acceleration α detected by the acceleration sensor 62 may be the pitch direction.

The stroke sensor 64 is attached to the hydraulic cylinder 20 and detects the stroke amount of the piston rod 23 of the hydraulic cylinder 20. The stroke amount detected by the stroke sensor 64 is input to the control device 60. In addition, as a distance detection part which detects the relative distance of the flame | frame 2 and the cabin 6, it is not limited to the stroke sensor 64, If the relative distance of the flame | frame 2 and the cabin 6 can be detected, what kind of form It may be a distance detection sensor, and may be, for example, a displacement sensor or a proximity sensor using light, a magnetic field, a sound wave or the like. In addition, it may be detected how much the position of the cabin 6 with respect to the frame 2 is displaced in the vertical direction from the neutral position.

The inclination sensor 66 is attached to the frame 2 and detects the inclination of the frame 2, that is, the inclination of the traveling road surface. The degree of inclination detected by the inclination sensor 66 is input to the control device 60.

The control device 60 controls the buffer unit 10 and the cabin height adjustment unit 50 based on the values detected by the

various sensors

62, 64, 66 described above. The control device 60 is configured by a microcomputer provided with a CPU (central processing unit), a ROM (read only memory), a RAM (random access memory), and an I / O interface (input / output interface). The RAM stores data in the processing of the CPU, the ROM stores in advance a control program of the CPU, etc., and the I / O interface is used to input and output information with the connected device. Control device 60 may be incorporated in a control device that controls an engine or a vehicle. The control performed by the control device 60 will be specifically described below.

First, damping force adjustment control performed by the control device 60 will be described with reference to FIG. FIG. 5 is a flowchart showing a control procedure of damping force adjustment control performed by the control device 60.

In the first step S10, the acceleration sensor 62 detects the acceleration α in the vibration direction of the cabin 6. The detected acceleration α is transmitted to the control device 60.

Next, in step S11, FFT processing is performed on the acceleration α received by the control device 60 to calculate the power spectral density at each frequency. The power spectral density represents each frequency component of the waveform as the magnitude of power.

In step S12, the power spectral density Px at the resonance frequency fm of the cabin 6 is calculated from the power spectral density calculated in step S11.

Subsequently, in step S13, it is determined whether the power spectral density Px at the resonance frequency fm of the cabin 6 calculated in step S12 is equal to or higher than a threshold value Pc as a predetermined value. If the power spectral density Px is equal to or higher than the threshold Pc, the process proceeds to step S14. If the power spectral density Px is lower than the threshold Pc, the process proceeds to step S15.

In step S14, the control device 60 applies a current to the solenoid 33 of the damping force switching valve 30. When current is applied to the solenoid 33, the position of the damping force switching valve 30 is switched to the second position 31b where the flow passage area is small. By reducing the flow passage area of the communication passage 28 in this manner, the resistance imparted to the hydraulic oil flowing through the communication passage 28 increases. As a result, the damping force generated by the buffer 10 increases, and the vibration in the pitch direction of the cabin 6 is suppressed by the buffer 10.

On the other hand, in step S <b> 15, the control device 60 applies no current to the solenoid 33 of the damping force switching valve 30. Since no current is applied to the solenoid 33, the position of the damping force switching valve 30 is held by the biasing force of the spring 32 at the first position 31a where the flow passage area is large. In this case, since the flow passage area of the communication passage 28 can not be reduced, almost no resistance is given to the hydraulic oil flowing through the communication passage 28. As a result, the damping force generated by the buffer 10 is reduced. However, since the cabin 6 does not generate vibration that needs to be suppressed, there is no effect even if the damping force generated by the buffer 10 is reduced. Rather, the traveling road surface is reduced by reducing the damping force generated by the buffer 10. It can suppress that the up-and-down motion and vibration which are transmitted to the frame 2 are transmitted to the cabin 6 as it is.

Thus, in the cabin damping system 100, when the power spectral density Px at the resonance frequency fm of the cabin 6 is large, that is, when the cabin 6 vibrates at the resonance frequency fm, the damping force generated by the buffer unit 10 is large. When the power spectral density Px at the resonance frequency fm of the cabin 6 is small, that is, when the cabin 6 is not vibrating at the resonance frequency fm, the damping force generated by the buffer unit 10 is reduced. The reason why the damping force is switched in this way will be described below with reference to a specific example.

First, the case where the tractor 1 travels on a road surface where relatively moderate unevenness is repeated as in a field will be described as an example. When the tractor 1 travels in the field, the frame 2 is continuously displaced in the vertical direction due to the unevenness of the field. On the other hand, the cabin 6 tries to maintain the height in the vertical direction by inertia. At this time, if the damping force generated by the buffer portion 10 is large and the hydraulic cylinder 20 does not easily expand and contract, the displacement of the frame 2 is easily transmitted to the cabin 6. For this reason, there is a possibility that the cabin 6 may be displaced in the vertical direction according to the unevenness of the field as well as the frame 2.

For this reason, in the cabin damping system 100, when the tractor 1 travels on a relatively gentle uneven road surface, the hydraulic oil flowing through the communication passage 28 does not apply current to the solenoid 33 of the damping force switching valve 30. And the damping force generated by the buffer 10 is reduced. As a result, the hydraulic fluid can easily move relatively smoothly between the piston side chamber 24 and the rod side chamber 25 through the communication passage 28, and the hydraulic cylinder 20 can easily expand and contract, whereby the displacement of the frame 2 is transmitted to the cabin 6 It becomes difficult.

As described above, in the cabin damping system 100, when it is determined that the cabin 6 does not vibrate at the resonance frequency fm, the resistance given to the hydraulic oil flowing through the communication passage 28 is reduced to reduce the shock absorber 10 The generated damping force is reduced, and the displacement of the frame 2 is transferred by the hydraulic cylinder 20 to suppress the transmission of the vibration of the frame 2 to the cabin 6.

Next, a case where the tractor 1 rides on a relatively large step will be described as an example. When the tractor 1 rides on the step, the frame 2 moves rapidly upward. On the other hand, the cabin 6 tries to stay at that position by inertia. For this reason, the piston rod 23 of the hydraulic cylinder 20 is rapidly pushed in by the inertia force of the cabin 6, and the hydraulic cylinder 20 contracts. Thus, when the hydraulic cylinder 20 contracts rapidly, the pressure in the compressed piston side chamber 24 rapidly increases, and the pressure in the increased piston side chamber 24 pushes the piston rod 23 back toward the cabin 6, a so-called restoring force. Become. At this time, if the resistance applied to the hydraulic oil flowing through the communication passage 28 is small, the hydraulic oil easily flows from the rod side chamber 25 to the piston side chamber 24 through the communication passage 28, so the restoring force of the piston side chamber 24 is It is transmitted to the cabin 6 through the piston rod 23 with little attenuation. For this reason, the cabin 6 is pushed upward in the direction away from the frame 2 by the pressure of the piston side chamber 24.

As the cabin 6 is displaced away from the frame 2, the hydraulic cylinder 20 also extends. As the hydraulic cylinder 20 extends, the pressure in the piston side chamber 24 gradually decreases, and eventually the cabin 6 begins to be displaced downward, that is, toward the frame 2 by gravity. As the piston rod 23 of the hydraulic cylinder 20 is pushed by the weight of the cabin 6, the piston side chamber 24 is compressed again.

As the pressure in the compressed piston side chamber 24 rises again, a restoring force that pushes up the cabin 6 is generated again in the piston side chamber 24. By this repetition, the cabin 6 vibrates in the vertical direction at a predetermined cycle. The vibration that occurs in this way must be suppressed because it is a continuous vibration that vibrates at the resonance frequency fm determined from the spring constant and the mass of the cabin 6 when the piston side chamber 24 and the accumulator 40 are regarded as fluid springs. Have difficulty.

Therefore, in the cabin damping system 100, when it is determined that the cabin 6 vibrates at the resonance frequency fm, the damping force generated by the buffer unit 10 is increased by increasing the resistance applied to the hydraulic oil flowing through the communication passage 28. The vibration of the cabin 6 is suppressed by attenuating both the force of pushing the piston rod 23 by the cabin 6 and the restoring force generated in the piston side chamber 24.

Next, with reference to FIG. 3, the cabin height adjustment control performed by the control device 60 will be described.

The control device 60 calculates the relative distance between the frame 2 and the cabin 6 from the stroke amount of the piston rod 23 of the hydraulic cylinder 20 detected by the stroke sensor 64, and the calculated actual relative distance is a predetermined target relative. The cabin height adjustment unit 50 is controlled to be the distance.

If the actual relative distance is smaller than the target relative distance, the controller 60 switches the position of the direction switching valve 52 of the cabin height adjustment unit 50 to the extended position 52a. When the direction switching valve 52 is switched to the extension position 52 a, the hydraulic fluid discharged from the hydraulic pump 51 flows into the piston side chambers 24 of the pair of hydraulic cylinders 20 through the supply passage 55 and the supply and discharge passage 56. As a result, the pair of hydraulic cylinders 20 extend synchronously, and the actual relative distance approaches the target relative distance.

If the actual relative distance is larger than the target relative distance, the controller 60 switches the position of the direction switching valve 52 of the cabin height adjustment unit 50 to the contracted position 52b. When the directional control valve 52 is switched to the contracted position 52b, the hydraulic oil in the piston side chamber 24 is returned to the tank T through the supply and discharge passage 56 and the discharge passage 57. As a result, the pair of hydraulic cylinders 20 contract in synchronization, and the actual relative distance approaches the target relative distance.

Then, when the actual relative distance and the target relative distance match, the control device 60 switches the position of the direction switching valve 52 of the cabin height adjustment unit 50 to the stop position 52c. When the directional control valve 52 is switched to the stop position 52c, the supply of hydraulic fluid to the piston side chamber 24 is shut off and the discharge of hydraulic fluid from the piston side chamber 24 is stopped. Thereby, the extension and contraction operation of the pair of hydraulic cylinders 20 is stopped.

As described above, the control device 60 controls the cabin height adjusting unit 50 to adjust the amount of expansion and contraction of the pair of hydraulic cylinders 20 so that the actual relative distance and the target relative distance match. The target relative distance is set such that when the relative distance between the frame 2 and the cabin 6 becomes the target relative distance, the position of the piston 22 is not in the vicinity of the upper end or the lower end of the cylinder tube 21 in the cylinder tube 21. Be done. By setting the target relative distance in this manner, the piston 22 is less likely to hit the upper end or the lower end of the cylinder tube 21 even when the relative distance between the frame 2 and the cabin 6 changes due to vibration. Vibration can be damped or transmission of vibration can be suppressed. The target relative distance may be changeable by the operator operating the dial or the like. In this case, the workability of the tractor 1 can be improved by appropriately adjusting the height of the cabin 6 so as to ensure the visibility from the cabin 6.

Further, the control device 60 changes the target relative distance in accordance with the degree of inclination of the frame 2 detected by the inclination sensor 66, that is, the degree of inclination of the traveling road surface. Specifically, the controller 60 increases the target relative distance when climbing uphill, and reduces the target relative distance when descending downhill, thereby reducing the cabin The cabin height adjustment unit 50 is controlled so that 6 is in a horizontal state. In addition, the inclination sensor 66 may be provided in the cabin 6, and in this case, the control device 60 controls the cabin height adjustment unit 50 so that the detection value of the inclination sensor 66 indicates a horizontal state.

Thus, the operability of the tractor 1 can be improved by being able to maintain the cabin 6 in a horizontal state regardless of the degree of inclination of the traveling road surface. In addition, the cabin height adjustment part 50 which adjusts the height of the cabin 6 is a function which can be added with respect to the cabin damping system 100 as needed, and does not necessarily need to be integrated. In addition, the cabin height adjustment control may be performed such that the position of the cabin 6 with respect to the frame 2 is always in a neutral position in the vertical direction without using the stroke sensor 64 or the like. In addition to the automatic adjustment mode in which the cabin height adjustment control adjusts the height of the cabin 6 with respect to the frame 2 according to the detection value of the stroke sensor 64, a cabin height adjustment lever (not shown) is operated by the operator A manual adjustment mode may be provided in which the height of the cabin 6 relative to the frame 2 is adjusted.

According to the first embodiment described above, the following effects can be obtained.

In the cabin damping system 100, the resistance that the damping force switching valve 30 applies to the hydraulic fluid flowing through the communication passage 28 based on the acceleration α in the vibration direction of the cabin 6 detected by the acceleration sensor 62 and the resonant frequency fm of the cabin 6 Control. Thus, according to the vibration condition of the cabin 6, by switching the damping force generated by the buffer unit 10, the vibration of the cabin 6 can be accurately suppressed.

Moreover, in the cabin damping system 100, when the cabin 6 vibrates at the resonance frequency fm, the damping force generated by the buffer unit 10 is increased to suppress the vibration of the cabin 6, and the cabin 6 vibrates at the resonance frequency fm. When not, the damping force generated by the buffer unit 10 is reduced to suppress the transmission of vibration from the frame 2 to the cabin 6. As a result, it is possible to improve the riding comfort of a work vehicle such as a tractor 1 traveling on rough terrain.

Further, in the cabin damping system 100, the vibration of the frame 2 and the cabin 6 can be damped or absorbed by the hydraulic cylinder 20 only by arranging the hydraulic cylinder 20 between the frame 2 and the cabin 6. For this reason, it is possible to mount the cabin damping system 100 also to the tractor 1 which does not have much space between the frame 2 and the cabin 6.

Next, a modification of the first embodiment will be described. The modifications described later are also within the scope of the present invention, and the configurations shown in the modifications and the configurations described in the above embodiments may be combined, the configurations described in different embodiments described below may be combined, or the following differences It is also possible to combine the configurations described in the modification.

In the first embodiment, whether or not the cabin 6 vibrates at the resonance frequency fm is determined based on the value of the power spectral density Px at the resonance frequency fm. Instead of this, it may be determined whether or not the cabin 6 vibrates at the resonance frequency fm based on the magnitude of the effective value Xr of the octave band. The effective value Xr of the octave band will be specifically described below.

The octave band is a frequency range of 1/1 octave when the resonance frequency fm of the cabin 6 is a central frequency. Specifically, when the upper limit frequency is fu1 and the lower limit frequency is fd1, the upper limit frequency fu1 and the lower limit frequency fd1 of 1/1 octave can be obtained by the following equations (1) and (2).

fu1 = 2 2 × fm 1.4 1.4142 × fm formula (1)
fd1 = fm / √2 ÷ fm 1.4142 ··· Formula (2)

The frequency range of the octave band may be 1/3 octave. The upper limit frequency fu2 and the lower limit frequency fd2 of the 1/3 octave can be obtained by the following equations (3) and (4).

fu2 = 6√2 × fm 1.1 1.1225 × fm formula (3)
fd2 = fm / 6 2 2 fm ÷ 1.1225 formula (4)

The effective value Xr of the octave band is determined by integrating the power spectral density Px in the range of the upper limit frequency fu and the lower limit frequency fd. The controller 60 determines that the cabin 6 is vibrating at the resonance frequency fm when the effective value Xr of the octave band obtained in this manner becomes equal to or greater than the predetermined threshold value Xc, and the damping force switching valve 30 To the second position 31 b to increase the resistance applied to the hydraulic fluid flowing through the communication passage 28. Thereby, the same effects as the effects of the first embodiment can be obtained.

Further, in the first embodiment, the damping force switching valve 30 is a two-position switching valve, and the flow passage area of the communication passage 28 is switched in two steps. Instead of this, the damping force switching valve 30 may change the flow passage area of the communication passage 28 in multiple stages or continuously. In this case, the valve body 31 may be a spool valve capable of changing the communication opening degree by being displaced in the axial direction, or a rotary valve capable of changing the communication opening degree by being displaced in the circumferential direction It is also good. Further, as the solenoid 33, a proportional solenoid may be used or a stepping motor may be used.

Also, in this way, when it is possible to change the flow passage area of the communication passage 28 in multiple stages or continuously, the value of the power spectral density Px and the value of the effective value Xr of the octave band may be used. Accordingly, it is possible to control the magnitude of the damping force generated by the buffer 10 more finely by proportionally changing the flow passage area of the communication passage 28. Further, as compared with the case where the flow passage area of the communication passage 28 is switched in two steps, it is possible to make the change of the expansion and contraction speed of the hydraulic cylinder 20 and the like which occur when the damping force is changed loose.

Second Embodiment
Next, a cabin damping system 200 according to a second embodiment of the present invention will be described with reference to FIG. Hereinafter, differences from the first embodiment will be mainly described, and the same components as those of the cabin damping system 100 of the first embodiment will be assigned the same reference numerals and descriptions thereof will be omitted.

The basic configuration of the cabin damping system 200 is the same as that of the cabin damping system 100 according to the first embodiment. In the cabin damping system 100 according to the first embodiment, the magnitude of the damping force generated by the buffer unit 10 by changing the flow passage area of the communication passage 28 communicating the piston side chamber 24 and the rod side chamber 25 with the damping force switching valve 30. However, in the cabin damping system 200, the damping force switching valve 130 is used to change the flow path area of the connection passage 42 connecting the piston side chamber 124 and the oil chamber 41a of the accumulator 40. The difference is that the magnitude of the damping force generated by the portion 110 is changed.

As shown in FIG. 6, the cabin damping system 200 has a buffer unit 110 capable of changing a damping force that damps the vibration of the cabin 6, and the buffer unit 110 as in the cabin damping system 100 of the first embodiment. And a control unit 60 for controlling the damping force generated by the buffer unit 110.

The buffer unit 110 has a pair of hydraulic cylinders 120 as in the case of the buffer unit 10 of the first embodiment.

The hydraulic cylinder 120 has a cylinder tube 121 having one end connected to the frame 2 and having hydraulic oil sealed therein, and a piston side chamber 124 slidably disposed in the cylinder tube 121 and having the inside of the cylinder tube 121 as a first fluid chamber. And a piston side wall 125 as a second fluid chamber, and a piston rod 123 having one end connected to the piston 122 and the other end connected to the cabin 6. The piston 122 is formed with a flow passage 122 c that allows hydraulic fluid to pass between the piston side chamber 124 and the rod side chamber 125. The hydraulic cylinder 120 has a base end portion of the cylinder tube 121 connected to the frame 2 via the connection portion 126, and a tip end portion of the piston rod 123 connected to the cabin 6 via the connection portion 127.

The buffer unit 110 further includes a damping force switching valve 130 provided in a connection passage 42 connecting the piston side chamber 124 and the oil chamber 41 a of the accumulator 40.

The damping force switching valve 130 is an electromagnetic two-position switching valve, and is actuated by the valve body 131 and a current supplied from the control device 60 to apply a biasing force to the valve body 131, and a biasing force of the solenoid 133 And a spring 132 for applying a biasing force to the valve body 131.

The valve body 131 has a large flow passage area, a first position 131a which hardly gives resistance to the hydraulic fluid flowing through the connection passage 42, and a relatively small resistance to the hydraulic fluid flowing through the connection passage 42. And 2 positions 131 b.

The position of the valve body 131 is switched by the biasing force of the spring 132 and the biasing force of the solenoid 133. Specifically, when no current is applied to the solenoid 133, the biasing force of the spring 132 holds the first position 131a, and the current is applied to the solenoid 133 and the biasing force of the solenoid 133 applied to the valve body 31 is When the biasing force of the spring 132 is exceeded, it is switched to the second position 131 b. The damping force switching valve 130 is configured such that the position of the valve body 131 is the second position 131 b when no current is applied to the solenoid 133 and the first position 131 a when the current is applied to the solenoid 133 It may be

When the position of the damping force switching valve 130 is at the first position 131a, when the hydraulic cylinder 120 expands and contracts, the hydraulic fluid can move back and forth between the piston side chamber 124 and the oil chamber 41a without a relative resistance. The resulting damping force is minimal. On the other hand, when the position of the damping force switching valve 130 is at the second position 131 b, when the hydraulic cylinder 120 expands and contracts, movement of hydraulic fluid between the piston side chamber 124 and the oil chamber 41 a is restricted. The damping force that occurs is maximized.

Supply of current to the solenoid 133 is performed by the control device 60, and the magnitude of the damping force generated by the buffer unit 110 is controlled by the control device 60 as in the first embodiment.

The configurations of the cabin height adjustment unit 50 and the control device 60 are the same as in the first embodiment, and thus the description thereof will be omitted.

In the cabin damping system 200 configured as described above, the damping force adjustment control is performed by the control device 60 along the flow shown in FIG. 5, similarly to the cabin damping system 100 of the first embodiment.

It is the above-mentioned damping force switching valve 130 that is controlled by the controller 60 in damping force adjustment control. For this reason, in the cabin damping system 200, when it is determined that the cabin 6 vibrates at the resonance frequency fm, the damping force generated by the buffer portion 110 is increased by increasing the resistance applied to the hydraulic oil flowing through the connection passage 42. The vibration of the cabin 6 is suppressed by attenuating both the force of pushing the piston rod 123 by the cabin 6 and the restoring force generated in the piston side chamber 124.

On the other hand, when it is determined that the cabin 6 does not vibrate at the resonance frequency fm, the resistance applied to the hydraulic oil flowing through the connection passage 42 is reduced to reduce the damping force generated by the buffer 110 and the displacement of the frame 2 Is transferred by the hydraulic cylinder 120 to suppress the transmission of the vibration of the frame 2 to the cabin 6.

Thus, in the cabin damping system 200, as in the case of the cabin damping system 100 of the first embodiment, the vibration of the cabin 6 is changed by changing the damping force generated by the buffer unit 110 according to the vibration situation of the cabin 6. Is suppressed.

About cabin height adjustment control performed by control device 60 of cabin damping system 200, since it is the same as that of the above-mentioned 1st embodiment, the explanation is omitted.

According to the above second embodiment, the following effects can be obtained.

In the cabin damping system 200, the resistance that the damping force switching valve 130 applies to the hydraulic oil flowing through the connection passage 42 based on the acceleration α in the vibration direction of the cabin 6 detected by the acceleration sensor 62 and the resonance frequency fm of the cabin 6. Control. Thus, according to the vibration condition of the cabin 6, by switching the damping force which the buffer part 110 produces, the vibration of the cabin 6 can be suppressed appropriately.

Further, in the cabin damping system 200, the vibration of the frame 2 and the cabin 6 can be damped or absorbed by the hydraulic cylinder 120 only by arranging the hydraulic cylinder 120 between the frame 2 and the cabin 6. For this reason, it is possible to mount the cabin damping system 200 also to the tractor 1 which does not have much space between the frame 2 and the cabin 6.

Third Embodiment
Next, a cabin damping system 300 according to a third embodiment of the present invention will be described with reference to FIGS. 7 and 8. Hereinafter, differences from the first embodiment will be mainly described, and the same components as those of the cabin damping system 100 of the first embodiment will be assigned the same reference numerals and descriptions thereof will be omitted.

In the cabin damping system 100 according to the first embodiment, the buffer unit 10 includes the hydraulic cylinder 20 and the accumulator 40, whereas in the cabin damping system 300, the buffer unit 210 includes the hydraulic damper 220 and a coil spring. It differs in that it has 240 and.

As shown in FIG. 7, the cabin damping system 300 includes a buffer unit 210 capable of changing a damping force that damps the vibration of the cabin 6 and a control device 60 that controls the damping force generated by the buffer unit 210. .

The buffer unit 210 has a hydraulic damper 220 as a pair of hydraulic cylinders provided on the right side and the left side of the vehicle between the cabin 6 and the frame 2. Since the pair of hydraulic dampers 220 have the same configuration, only one configuration will be described below.

The hydraulic damper 220 has a cylinder tube 221, one end of which is connected to the frame 2 and in which the hydraulic oil is sealed, and a piston side chamber 224 slidably disposed in the cylinder tube 221 and having a cylinder tube 221 as a first fluid chamber. The piston 222 is divided into a rod side chamber 225 as a second fluid chamber, and a piston rod 223 has one end coupled to the piston 222 and the other end coupled to the cabin 6.

Further, as shown in FIG. 8, the piston 222 has

passages

222 a and 222 b that communicate the piston side chamber 224 and the rod side chamber 225. The passage 222a is opened to open the passage 222a when the hydraulic damper 220 is extended, and is an extension side that resists the flow of hydraulic fluid moving from the rod side chamber 225 to the piston side chamber 224 through the passage 222a. A damping valve 229a is provided. The passage 222b is provided with a check valve 229b that opens to open the passage 222b when the hydraulic damper 220 contracts.

The hydraulic damper 220 is provided on the outer peripheral side of the cylinder tube 221, and includes a reservoir 271 for storing hydraulic oil, and a base valve 272 in which

passages

273 and 274 for communicating the reservoir 271 and the piston side chamber 224 are formed. Furthermore, it has. The passage 273 is provided with a check valve 275 that opens to open the passage 273 when the hydraulic damper 220 extends. In the passage 274, when the hydraulic damper 220 contracts, it opens to open the passage 274, and also serves as a pressure-side damping valve that resists the flow of hydraulic fluid moving from the piston side chamber 224 to the reservoir 271 through the passage 274 276 are provided.

Thus, the hydraulic damper 220 generates a damping force by the expansion side damping valve 229a provided to the piston 222 when extending, and attenuates by the pressure side damping valve 276 provided to the base valve 272 when contracting. It is a so-called double cylinder type damper that generates a force. The hydraulic damper 220 has a base end portion of the cylinder tube 221 connected to the frame 2 via the connection portion 226, and a tip end portion of the piston rod 223 connected to the cabin 6 via the connection portion 227.

Further, as shown in FIG. 8, the buffer unit 210 further includes a damping force switching valve 30 provided inside the piston rod 23. The damping force switching valve 30 is an electromagnetic two-position switching valve provided on a communication passage 228 formed in a piston rod 223 communicating the piston side chamber 224 and the rod side chamber 225. The configuration of the damping force switching valve 30 is the same as that of the first embodiment, and thus the description thereof will be omitted. The supply of current to the solenoid 33 is performed by the control device 60, and the magnitude of the damping force generated by the buffer unit 210 is controlled by the control device 60 as in the first embodiment.

The buffer unit 210 further includes a coil spring 240 as an elastic member interposed in a compressed state between the frame 2 and the cabin 6. When the damping force switching valve 30 does not apply resistance to the hydraulic fluid flowing through the communication passage 228 and the damping force generated by the buffer unit 210 is small, the cabin 6 is elastically supported by the coil spring 240 with respect to the frame 2 The impact received by 210 is stored in the coil spring 240 as elastic energy.

As described above, the buffer unit 210 has a vibration damping function as well as a shock absorbing function as the buffer unit 10 in the first embodiment.

The configuration of the control device 60 is the same as that of the first embodiment, and thus the description thereof is omitted.

In the cabin damping system 300 configured as described above, the damping force adjustment control is performed by the control device 60 along the flow shown in FIG. 5 as in the cabin damping system 100 of the first embodiment.

It is the above-mentioned damping force switching valve 30 that is controlled by the controller 60 in damping force adjustment control. Therefore, in the cabin damping system 300, when it is determined that the cabin 6 vibrates at the resonance frequency fm, the damping force generated by the hydraulic damper 220 is increased by increasing the resistance applied to the hydraulic fluid flowing through the communication passage 228 The vibration of the cabin 6 is suppressed by attenuating both the force with which the cabin 6 pushes the piston rod 223 and the restoring force generated by the coil spring 240.

On the other hand, when it is determined that the cabin 6 does not vibrate at the resonance frequency fm, the resistance applied to the hydraulic fluid flowing through the communication passage 228 is reduced to reduce the damping force generated by the hydraulic damper 220, thereby displacing the frame 2. Are transmitted by the coil spring 240 to suppress the transmission of the vibration of the frame 2 to the cabin 6.

As described above, in the cabin damping system 300, as in the case of the cabin damping system 100 of the first embodiment, the damping force generated by the buffer unit 210 is changed according to the vibration situation of the cabin 6, thereby vibrating the cabin 6 Is suppressed.

According to the above third embodiment, the following effects can be obtained.

In the cabin damping system 300, the resistance that the damping force switching valve 30 applies to the hydraulic oil flowing through the communication passage 228 based on the acceleration α in the vibration direction of the cabin 6 detected by the acceleration sensor 62 and the resonance frequency fm of the cabin 6. Control. Thus, according to the vibration condition of the cabin 6, by switching the damping force which the buffer part 210 produces, the vibration of the cabin 6 can be suppressed appropriately.

Further, in the cabin damping system 300, the vibrations of the frame 2 and the cabin 6 are damped or absorbed by the hydraulic damper 220 and the coil spring 240 provided between the frame 2 and the cabin 6. Thus, in the cabin damping system 300, since the damper and spring conventionally used as a shock absorbing device are used for damping of the cabin 6, the manufacturing cost of the cabin damping system 300 can be reduced. .

Hereinafter, the configuration, operation, and effects of the embodiment of the present invention will be collectively described.

The

cabin damping system

100, 200, 300 is provided between the frame 2 of the tractor 1 and the cabin 6, and has a

buffer

10, 110, 210 capable of changing the damping force that damps the vibration of the cabin 6, and at least the cabin Based on the acceleration sensor 62 for detecting the acceleration α of the cabin 6 in the vibration direction 6 and the acceleration α of the cabin 6 detected by the acceleration sensor 62 and the resonance frequency fm of the cabin 6, the

buffer units

10, 110 and 210 are generated. And a controller 60 for controlling the magnitude of the damping force.

In this configuration, based on the acceleration α in the vibration direction of the cabin 6 detected by the acceleration sensor 62 and the resonance frequency fm of the cabin 6, the magnitude of the damping force generated by the

buffer units

10, 110, 210 is controlled. Thus, according to the vibration condition of the cabin 6, the vibration of the cabin 6 can be suppressed appropriately by controlling the magnitude of the damping force generated by the

buffer sections

10, 110, 210.

Further, control device 60 calculates power spectral density Px at resonance frequency fm of cabin 6 from acceleration α detected by acceleration sensor 62, and when power spectral density Px is equal to or higher than threshold value Pc, or power spectral density Px is As it becomes higher, the magnitude of the damping force generated by the

shock absorbers

10, 110, 210 is increased.

In this configuration, when the power spectral density Px at the resonance frequency fm of the cabin 6 is large and it is determined that the cabin 6 vibrates at the resonance frequency fm, the damping force generated by the

buffer units

10, 110, 210 is large. Vibration of the cabin 6 is suppressed by doing. On the other hand, when the power spectral density Px at the resonance frequency fm of the cabin 6 is small and it is determined that the cabin 6 does not vibrate at the resonance frequency fm, the damping force generated by the

buffer units

10, 110, 210 should be reduced. Transmission of vibration from the frame 2 to the cabin 6 is suppressed. As a result, the vibration of the cabin 6 is accurately suppressed, and the riding comfort of the tractor 1 traveling on rough terrain can be improved.

Further, the control device 60 calculates the effective value Xr of the octave band centering on the resonance frequency fm of the cabin 6 based on the acceleration α detected by the acceleration sensor 62, and the effective value Xr of the octave band is equal to or more than the threshold Xc. At the same time, or as the effective value Xr of the octave band increases, the magnitude of the damping force generated by the

buffers

10, 110, 210 is increased.

In this configuration, when it is determined that the effective value Xr of the octave band whose center frequency is the resonance frequency fm of the cabin 6 is large and it is determined that the cabin 6 vibrates at the resonance frequency fm, the

buffer units

10, 110, 210 Vibration of the cabin 6 is suppressed by increasing the damping force generated by On the other hand, when the effective value Xr of the octave band centering on the resonance frequency fm of the cabin 6 is small and it is determined that the cabin 6 is not vibrating at the resonance frequency fm, the

buffer portions

10, 110, 210 are generated Transmission of vibration from the frame 2 to the cabin 6 is suppressed by reducing the damping force. As a result, the vibration of the cabin 6 is accurately suppressed, and the riding comfort of the tractor 1 traveling on rough terrain can be improved.

The

buffer sections

10 and 210 have

cylinder tubes

21 and 221 each having one end connected to the frame 2 and sealed with the working oil, and slidably disposed in the

cylinder tubes

21 and 221.

Pistons

22 and 222 that divide the piston into a

piston side chamber

24 and 224 and a

rod side chamber

25 and 225, a

piston rod

23 and 223 having one end coupled to the

piston

22 and 222 and the other end connected to the cabin 6, a piston side chamber 24 A hydraulic cylinder (hydraulic cylinder 20, hydraulic damper 220) having

communication passages

28 and 228 communicating the

rod side chamber

25 and 225 with the rod side chamber 25 and a damping force for giving resistance to the hydraulic oil flowing through the

communication passages

28 and 228 The control device 60 controls the damping force switching valve 30 to change the resistance applied to the hydraulic fluid. Adjusting the magnitude of the damping

force buffer portion

10, 210 is caused by.

In this configuration, the magnitude of the damping force generated by the

shock absorbers

10 and 210 changes the resistance applied to the hydraulic fluid flowing in the

communication passage

28 and 228 that connects the

piston side chamber

24 and 224 and the

rod side chamber

25 and 225. It is changed by. As described above, the shock absorbing portion 10 is controlled by controlling the flow of hydraulic fluid that travels between the

piston side chamber

24, 224 and the

rod side chamber

25, 225 as the fluid pressure cylinder (the hydraulic cylinder 20, the hydraulic damper 220) expands and contracts. , 210 can easily be changed.

The buffer unit 10 further includes an accumulator 40 connected to the piston side chamber 24.

In this configuration, the piston side chamber 24 functions as a fluid spring together with the accumulator 40 by the accumulator 40 being connected to the piston side chamber 24. Therefore, the vibration of the frame 2 and the cabin 6 can be damped or absorbed by the hydraulic cylinder 20 simply by providing the hydraulic cylinder 20 between the frame 2 and the cabin 6. As a result, the cabin damping system 100 can be made compact.

The buffer unit 210 further includes a coil spring 240 interposed in a compressed state between the frame 2 and the cabin 6.

In this configuration, the vibration of the frame 2 and the cabin 6 is damped or absorbed by the hydraulic damper 220 and the coil spring 240 provided between the frame 2 and the cabin 6. Thus, in the cabin damping system 300, since the damper and spring conventionally used as a shock absorbing device are used for damping of the cabin 6, the manufacturing cost of the cabin damping system 300 can be reduced. .

The buffer portion 110 has a cylinder tube 121 having one end connected to the frame 2 and a hydraulic oil sealed therein, and a piston side chamber 124 and a rod side chamber 125 which are slidably disposed in the cylinder tube 121. A hydraulic cylinder 120 having a piston 22 defining at one end and a piston rod 123 having one end coupled to the piston 22 and the other end coupled to the cabin 6, and an accumulator 40 connected to the hydraulic cylinder 120 through a connecting passage 42 The damping force switching valve 130 applies resistance to the hydraulic fluid flowing through the connection passage 42, and the controller 60 controls the damping force switching valve 130 to buffer by changing the resistance applied to the hydraulic fluid. The magnitude of the damping force generated by the part 110 is adjusted.

In this configuration, the magnitude of the damping force generated by the buffer portion 110 is changed by changing the resistance applied to the hydraulic fluid flowing through the connection passage 42 communicating the hydraulic cylinder 120 and the accumulator 40. Thus, the magnitude of the damping force generated by the buffer portion 110 can be easily changed by controlling the flow of the hydraulic fluid flowing back and forth in the connection passage 42 as the hydraulic cylinder 120 expands and contracts.

In addition,

cabin damping system

100, 200 is provided with a stroke sensor 64 for detecting the relative distance between frame 2 and cabin 6, and by supplying and discharging hydraulic oil to

piston side chambers

24, 124, frame 2 and cabin 6 And the control device 60 controls the cabin height adjustment unit 50 such that the relative distance detected by the stroke sensor 64 becomes a predetermined size. And adjust the relative distance between the frame 2 and the cabin 6.

In this configuration, it is possible to adjust the relative distance between the frame 2 and the cabin 6 by supplying and discharging the working oil to the

piston side chambers

24 and 124, and to set the height of the cabin 6 to a desired height. For this reason, ensuring of the field of vision in cabin 6 becomes easy, and the workability of tractor 1 can be improved.

In addition,

cabin damping system

100, 200 further includes a tilt sensor 66 that detects the tilt of frame 2, and control device 60 controls cabin height adjustment unit 50 according to the tilt detected by tilt sensor 66. , Adjust the relative distance between the frame 2 and the cabin 6.

In this configuration, the relative distance between the frame 2 and the cabin 6 is adjusted according to the inclination of the frame 2. For this reason, regardless of the inclination of the traveling road surface, the cabin 6 can be maintained in the horizontal state, and the workability of the tractor 1 can be improved.

As mentioned above, although the embodiment of the present invention was described, the above-mentioned embodiment showed only a part of application example of the present invention, and in the meaning of limiting the technical scope of the present invention to the concrete composition of the above-mentioned embodiment. Absent.

The present application claims priority based on Japanese Patent Application No. 2017-173509 filed on September 8, 2017, to the Japan Patent Office, and the entire contents of this application are incorporated herein by reference.

Claims

A cabin damping system for suppressing vibration of a cabin of a work vehicle,
A buffer provided between the frame of the work vehicle and the cabin, wherein the damping force capable of damping the vibration can be changed;
An acceleration detection unit for detecting an acceleration of the cabin at least in the direction of the vibration;
A control unit configured to control a magnitude of the damping force generated by the buffer unit based on the acceleration of the cabin detected by the acceleration detection unit and a resonant frequency of the cabin; .
It is a cabin damping system of the work vehicle according to claim 1,
The control unit calculates a power spectral density at a resonance frequency of the cabin from the acceleration detected by the acceleration detection unit,
A cabin damping system for a working vehicle, wherein the magnitude of the damping force generated by the buffer unit is increased when the power spectral density is equal to or higher than a predetermined value, or as the power spectral density increases.
It is a cabin damping system of the work vehicle according to claim 1,
The control unit calculates an effective value of an octave band centering on a resonance frequency of the cabin based on the acceleration detected by the acceleration detection unit,
A cabin damping system for a working vehicle, in which the magnitude of the damping force generated by the buffer unit is increased when the effective value of the octave band is equal to or greater than a predetermined value, or as the effective value of the octave band increases. .
It is a cabin damping system of the work vehicle according to claim 1,
The buffer unit is
A cylinder tube, one end of which is connected to the frame and in which the working fluid is enclosed, a piston slidably disposed in the cylinder tube and partitioning the inside of the cylinder tube into a first fluid chamber and a second fluid chamber; A fluid pressure cylinder having a piston rod having one end coupled to the piston and the other end coupled to the cabin, and a communication passage communicating the first fluid chamber and the second fluid chamber;
And a damping force switching valve that applies resistance to the working fluid flowing through the communication passage,
The cabin damping system for a working vehicle, wherein the control unit adjusts the magnitude of the damping force generated by the buffer unit by controlling the damping force switching valve and changing the resistance applied to the working fluid.
It is a cabin damping system of the work vehicle according to claim 4,
The cabin damping system for a working vehicle, wherein the buffer unit further includes an accumulator connected to the first fluid chamber.
It is a cabin damping system of the work vehicle according to claim 4,
The cabin damping system of a working vehicle, wherein the buffer unit further includes an elastic member interposed in a compressed state between the frame and the cabin.
It is a cabin damping system of the work vehicle according to claim 1,
The buffer unit is
A cylinder tube having one end connected to the frame and a working fluid sealed therein; and a piston slidably disposed in the cylinder tube for partitioning the inside of the cylinder tube into a first fluid chamber and a second fluid chamber; A fluid pressure cylinder having a piston rod having one end coupled to the piston and the other end coupled to the cabin;
An accumulator connected to the fluid pressure cylinder through a connection passage;
And a damping force switching valve that applies resistance to the working fluid flowing through the connection passage,
The cabin damping system for a working vehicle, wherein the control unit adjusts the magnitude of the damping force generated by the buffer unit by controlling the damping force switching valve and changing the resistance applied to the working fluid.
It is a cabin damping system of the work vehicle according to claim 4,
A distance detection unit that detects a relative distance between the frame and the cabin;
And a cabin height adjusting unit capable of adjusting a relative distance between the frame and the cabin by supplying and discharging a working fluid to and from the first fluid chamber,
The control unit controls the cabin height adjustment unit such that the relative distance detected by the distance detection unit becomes a predetermined size, and adjusts the relative distance between the frame and the cabin. Cabin damping system.
It is a cabin damping system of the work vehicle according to claim 8,
The apparatus further comprises an inclination detection unit that detects the inclination of the frame,
A cabin damping system for a working vehicle, wherein the control unit controls the cabin height adjustment unit according to the inclination detected by the inclination detection unit, and adjusts a relative distance between the frame and the cabin.