JP2008001345A - Vibration-isolating structure of cargo bed of truck - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively reduce the vibration generated on a cargo bed of a truck. <P>SOLUTION: In a vibration-isolating structure of a cargo bed of a truck, a cargo bed 4 is provided behind a cab 3, and a cargo bed floor part 4a is installed on an undercarriage base part 2 on a cargo bed space side. A front side of the cargo bed floor part 4a is mounted on the undercarriage base part 2 by a hinge 5 turnably only in the pitching direction, and a rear side of the cargo bed floor part 4a is elastically mounted on the undercarriage base part 2 by an air spring 6. By the turnable mounting of the front side of the cargo bed floor part and the elastic mounting on the rear side of the cargo bed, the vibration of the cargo bed is permitted in the pitching direction, and at the same time, the vibration of the cargo bed in the pitching mode is efficiently insulated while the pitching resonance frequency is the low frequency capable of obtaining the vibration-isolating effect. By the turnably mounting of the front side of the cargo bed, the cargo bed is mechanically restricted, and the posture of the cargo bed is stabilized. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a truck bed vibration-proof structure including a bed behind a cab.

A truck having a loading platform behind the cab is used for transporting all loads, and there is a problem of damage caused by the propagation of vibration from the loading platform of the truck.
On the other hand, conventionally, there have been proposed means for preventing vibration of the cargo bed. For example, in Patent Document 1, an up-down vibration isolating means in which an air spring and a vibration attenuator are arranged in parallel and a horizontal anti-vibration means made of laminated rubber are combined in series to form a base (a truck frame). A vibration isolator for transportation supporting vibration isolation has been proposed. According to this device, the load carrier is vibration-proof supported with respect to the base by air springs, air dampers, laminated rubber, etc., and the resonance frequency is set to 1 / √2 or less of the frequency that is the main input component. It has a structure that makes it difficult to transmit vibration to the carrier.

Further, in Patent Document 2, an inner case is attached to one of a base for placing an object to be loaded, a cargo bed or a floor surface supporting the base, and an outer case is attached to the other, and the cases are connected by a suspension member. A vibration isolator has been proposed in which a displacement restraining member for adjusting the effective length of the load is provided, and the position of this member is changed based on the amount of horizontal displacement of the loading platform. In this apparatus, the amount of horizontal relative displacement generated in the loading platform is detected, and based on the value, the effective length of the suspension member is made appropriate to reduce low-frequency vibration.
JP-A-2-262438 JP-A-3-288037

According to the proposed apparatus described above, an effect of reducing the vibration generated in the cargo bed more or less can be obtained. However, the structure of these devices uses a large number of air springs and air dampers, and further supports vibration isolation in the horizontal direction by laminated rubber, etc. It is difficult to realize.
・ Many anti-vibration parts are required and the cost is high. ・ It is necessary to maintain the level of the loading platform with all the air springs, and the control becomes complicated. ・ There is no structure that mechanically restrains the anti-vibration loading platform. It is difficult to restrain the movement of the loading platform against a large input such as at the time of a collision.

  Further, the truck bed vibration mainly has a low frequency of 20 Hz or less, and the natural frequency of the truck bed needs to be 5 Hz or less in order to obtain a sufficient vibration isolation effect. However, when an elastic material such as a rubber bush is used, it is necessary to increase the vibration isolation effect by lowering the natural frequency of the five degrees of freedom other than the pitching direction. To do this, it is necessary to use very soft rubber. However, since the load applied to the truck bed reaches several tons, there is a problem that the durability of the rubber cannot be secured if such soft rubber is used, and in reality, a low natural frequency as intended is realized. As a result, there is a problem that a sufficient anti-vibration effect cannot be obtained.

  The present invention has been made against the background of the above circumstances, and proposes a practical and inexpensive anti-vibration structure for a cargo bed in accordance with the problems of the truck by limiting its application to a truck for transportation. That is, the present invention can effectively reduce the vibration generated in the loading platform at low cost, and can also restrain the loading platform portion by high rigidity support, thereby controlling the loading platform posture. An object of the present invention is to provide an easy truck bed vibration isolation structure.

  That is, among the truck bed vibration-proof structures of the present invention, the invention according to claim 1 is a truck having a bed space behind the cab and a bed floor portion installed on the vehicle base portion on the load bed space side. It is a cargo bed anti-vibration structure, wherein the front side of the cargo bed floor is attached to the chassis base so as to be rotatable only in the pitching direction, and the rear side of the cargo bed floor is elastically attached to the chassis base. It is characterized by being.

  According to a second aspect of the invention of the truck bed anti-vibration structure according to the second aspect, the rear side of the cargo bed floor portion is elastically attached to the chassis base portion by interposing a gas spring. It is characterized by being.

  According to a third aspect of the invention of the truck bed vibration isolating structure according to the second aspect, a shock absorber is interposed between the cargo bed floor portion and the chassis base portion in parallel with the gas spring. Features.

  According to a fourth aspect of the invention of the truck bed vibration isolating structure according to the second or third aspect of the invention, in the invention according to the second or third aspect, a sensor for measuring a distance between the cargo bed floor portion and the chassis base portion, and gas to the gas spring are provided. Based on the gas supply source to supply, the gas control valve that controls the gas movement of the gas spring, and the output from the sensor, so that the distance between the cargo bed and the cargo bed floor at a stationary time is a predetermined distance, Gas pressure control means for controlling the gas pressure of the gas spring by controlling the gas control valve is provided.

  The invention of the truck bed vibration-proof structure according to claim 5 is the invention according to any one of claims 1 to 4, wherein the elastic stopper that prevents the cargo bed floor portion and the chassis base portion from approaching each other at a predetermined distance or more. It is characterized by providing.

  According to a sixth aspect of the invention of the truck bed vibration isolating structure according to the first or second aspect, in the invention according to the first or second aspect, in the elastic mounting, a displacement is caused between the rear side of the cargo bed floor portion and the chassis base portion. A shock absorber having a non-linear elasticity in which the spring coefficient is small when the amount is small and the spring coefficient is large when the amount of displacement is large is interposed.

  The truck bed vibration-proof structure according to claim 7 is the invention according to any one of claims 1 to 6, wherein the rear side of the bed floor part and the chassis base part are temporarily rigidly connected. It has a detachable connecting mechanism.

  According to the truck bed vibration-proof structure of the present invention, since the front side of the bed floor portion is attached to be rotatable only in the pitching direction, it is mechanically reliably restrained except for the rotational movement, The rear side of the cargo bed floor can effectively absorb vibration by elastic attachment in the pitching direction. As shown in FIG. 8, the vibration generated in the truck bed has a large amplitude in the vertical direction on the rear side of the bed, and the bed is moving close to pitching with respect to the vehicle. In addition, it is considered that the load loaded on the rear side of the loading platform having a large vibration is easily damaged even when the load is damaged. In truck transportation, it is important to suppress the vibration on the rear side of the loading platform. This is due to the load sharing between the front and rear wheels of the truck, and the rear wheel with a large load sharing needs to use a spring with a hard suspension, which makes it easier to receive input from the rear wheel side. This is because vibration becomes a problem. In the present invention, the front side of the loading platform is made to be a hinge that is movable in the rotational direction so that the movement of the loading platform is allowed in the pitching direction. By making it 1 / √2 or less than the input frequency (the unsprung resonance frequency of the rear wheel in question is about 10 to 15 Hz), it is structured to make it difficult to transmit the input vibration to the carrier.

  The elastic mounting between the cargo bed floor and the chassis base is not limited to a specific one as long as it exhibits an elastic force in the pitching direction, but a gas spring such as an air spring is not limited. preferable. The gas spring can realize a very low spring constant while supporting a large load, and can exhibit excellent vibration-proofing properties at low cost against an elastic material such as a rubber bush.

Further, by interposing a shock absorber in parallel with the gas spring, it is possible to obtain a function of suppressing a vibration at the resonance frequency by obtaining a resonance damping function hardly obtained with the gas spring.
In addition, in order to ensure the stability of the cargo bed floor during cargo handling work when the gas pressure in the gas spring leaks between the cargo bed floor portion and the chassis base portion, the cargo bed floor portion and the chassis base portion It is possible to provide an elastic stopper that prevents proximity beyond a predetermined interval. As a result, even when the air pressure of the vibration isolating structure is lost, it is possible to prevent the cargo bed floor from excessively moving.

  Further, in the elastic attachment between the cargo bed floor portion and the chassis base portion, a non-linear shock absorber can be interposed alone or in parallel with the gas spring or the like. As the non-linear shock absorber, an elastic member is used that exhibits elasticity in which the spring coefficient is small when the displacement amount is small and the spring coefficient is large when the displacement amount is large. For example, a gas spring that exhibits a small spring coefficient in an elastic region with a small amount of displacement, a gas spring that does not support due to gas pressure failure, etc., and a large spring coefficient in an elastic region with a large amount of displacement. . Examples of the non-linear characteristics include a substantially constant small spring coefficient up to a certain displacement amount, and a substantially constant large spring coefficient beyond a certain displacement amount. In addition, a spring whose characteristic increases as the amount of displacement increases can be used.

  For the non-linear shock absorber, an anti-vibration rubber tuned according to the shape and material characteristics can be used. According to the non-linear shock absorber, in the elastic region with a small amount of displacement, an anti-vibration function is exhibited together with a gas spring and the like, and an action of obtaining a resonance damping function and suppressing vibration at the resonance frequency can be obtained. Moreover, in the elastic region with a large amount of displacement, it functions to prevent excessive movement of the cargo bed floor when the gas pressure of the gas spring is lost. With this function, it is possible to reduce the number of parts by omitting the stoppers described above, thereby contributing to cost and weight reduction, and to make effective use of space.

In addition, as a loading platform floor portion of the present invention, it is possible to target a floor pan or the like installed on the loading platform or on the loading platform, and as a chassis base portion, a chassis frame on which these loading platform floor portions are installed. And cargo bed bottom.
Further, as described above, the present invention is limited to the transportation truck, but is preferably applied to a cabover type or semi-cabover type truck.

  As described above, the invention of the truck bed vibration isolating structure of the present invention has the cargo bed space behind the cab, and the truck bed vibration damping of the truck in which the cargo bed floor portion is installed on the vehicle base portion on the cargo bed space side. Since the front side of the cargo bed floor portion is rotatably attached to the chassis base portion only in the pitching direction and the rear side of the cargo bed floor portion is elastically attached to the chassis base portion. After allowing the vibration of the loading platform floor in the pitching direction by the elastic mounting provided on the front side of the loading platform floor and the elastic mounting provided on the rear side of the loading platform, the pitching resonance frequency is set as a low frequency that can obtain the anti-vibration effect. It becomes possible to effectively prevent the vibration of the platform in the pitching mode, which is most likely to cause a problem with the generated platform vibration. Further, the loading platform is mechanically restrained by the rotational mounting in front of the loading platform, and the posture of the loading platform can be stabilized.

  In addition, even when using a gas spring for elastic mounting, it is possible to use two gas springs such as an air spring, and it is possible to prevent vibration of the cargo bed with a very simple structure compared to the conventional example. In addition, since the loading platform is constrained by a rotational attachment such as a hinge other than the rotational direction, there is an effect that the problem as in the conventional example does not occur even for posture control and large input.

(Embodiment 1)
Below, one Embodiment of this invention is described based on FIGS. 1-4.
The truck 1 has a cab 3 and a loading platform 4, and the cab 3 and loading platform 4 are arranged side by side in a front-rear direction on a chassis frame 2 corresponding to a vehicle base portion.
The loading platform 4 has a loading platform bottom 4a corresponding to the loading platform floor, and the front side of the loading platform bottom 4a is attached to the chassis frame 2 via a hinge 5 so as to be rotatable in the pitching direction, Movement in directions other than the rotation direction is restricted. The hinge 5 is attached to the chassis frame 2 by a hinge attachment bracket 5a.
In the present invention, the rotational mounting of the cargo bed floor portion is not limited to the hinge, but may be anything that can be rotated only in the rotational direction by mechanical connection.

  The rear end of the cargo bed bottom 4a is attached to the chassis frame 2 via an air spring 6 corresponding to a gas spring. The air spring 6 is disposed on both the left and right sides, and is respectively supported by support members 6a and 6a. The upper and lower portions of the air spring 6 are fixed to the loading platform bottom 4 a and the chassis frame 2.

  In general, the air springs 6 and 6 used in a set of two on the right and left sides of the rear side of the loading platform take into account the mass allowed for the loading platform 4 and the resonance frequency thereof is the vibration isolation of the loading platform 4. The frequency is selected to be sufficiently low to obtain the effect. However, it is of course possible to use a larger number of air springs in order to handle a large load within the range where the targeted vibration isolation effect can be obtained, and it is possible to use only one air spring. It is also possible to do.

Further, air shock absorbers 7 and 7 are interposed between the cargo bed bottom 4a and the chassis frame 2 in parallel with the air springs 6 and 6 at the rear side end of the cargo bed bottom 4a. The upper portions and the lower portions of the absorbers 7 and 7 are fixed to the cargo bed bottom portion 4a and the chassis frame 2 by support members 7a and 7a, respectively. In addition, the structure of the air spring 6 and the shock absorber 7 is not specifically limited as this invention, What is necessary is just to be attached in the state which can be stroked up and down.
Air pressure supply pipes 8 are connected to the air spring 6 and the shock absorber 7 respectively. When air is supplied through the pipes, the air spring 6 strokes, and the loading platform 4 is lifted upward. The absorber 7 performs shock relaxation and vibration absorption in the vertical direction.

  An elastic stopper 9 is provided on the chassis frame 2 side between the cargo bed bottom 4a and the chassis frame 2. As shown in FIG. 4, the elastic stopper 9 has a clearance with respect to the cargo bed bottom portion 4a in a normal state where air is introduced into the air spring 6 and functions as a spring. Is possible. On the other hand, when the pressure of the air spring 6 is not sufficiently introduced (or eliminated) due to parking or the like, the elastic stopper 9 is in a state where the cargo bed bottom portion 4a is lower than the normal traveling state. In this case, the further lowering of the loading platform 4 is restricted. Further, when a large vibration is applied to the loading platform 4 side and cannot be absorbed by the air spring 6, the function of regulating the vibration of the loading platform 4 is also achieved. That is, the elastic stopper is a member having both a function of supporting the load of the loading platform instead of the air spring and a function of absorbing a displacement that could not be absorbed by the air spring at the time of large input. In normal times, the clearance between the cargo bed bottom 4a and the elastic stopper is set to be about 30 to 50 mm.

Further, the material of the elastic stopper 9 is not limited to a specific material, and can sufficiently support the load of the loading platform 4 and is not required for the air spring 6 or the shock absorber 7 by reducing the impact when the loading platform 4 is lowered. As long as it has an elastic force that does not apply a heavy load. The above structure constitutes a truck bed vibration isolation structure.
In this embodiment, the elastic stopper 9 is installed at one place on the left and right. However, for the purpose of distributing the shared load of the elastic stopper 9, a plurality of elastic stoppers 9 can be installed. It is also possible to perform the above function with an elastic stopper.

Next, the operation of the truck bed anti-vibration structure will be described.
By introducing air into the air spring 6 from the air pressure supply pipe 8, the cargo bed bottom 4 a is lifted up and supported by the air spring 6 and the shock absorber 7 to have a predetermined gap with respect to the chassis frame 2. At this time, the cargo bed bottom portion 4a can also vibrate with a gap with respect to the elastic stopper 9.

When the truck 1 travels in the above state, a pitching phenomenon occurs on the loading platform space side. As a result, the front side of the loading platform 4 on which the load is loaded is rotated only in the vehicle pitching direction with respect to the chassis frame 2 by the hinge 5, and the rear side of the loading platform is effectively affected by the pitching by the air spring 6 and the shock absorber 7. Reduced to In addition, as described above, the front side of the loading platform 4 is mechanically constrained by the hinge 5 except for the rotation in the pitching direction, so that the posture of the loading platform can be stably held.
That is, according to the present invention, normally contradictory actions such as stable support of the loading platform posture and vibration reduction can be obtained simultaneously.

(Embodiment 2)
In the above embodiment, the hinge and the elastic body are combined, and by including the elastic body, the deflection of the elastic body changes depending on the size of the load (the load applied to the elastic body). Will change.
Embodiment 2 below enables control of the posture of the loading platform according to the size of the load, and will be described based on FIGS. 5 and 6. In addition, about the structure similar to the said Embodiment 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted or simplified.

  A height sensor 10 for detecting the height of the loading platform 4 is disposed in the vicinity of the air spring 6. The height sensor 10 may be one that detects the height of the cargo bed bottom portion 4a, or may be one that detects the amount of gap between the cargo bed bottom portion 4a and the chassis frame 2. Any device that can know the position in the vertical direction may be used. The configuration of the height sensor 10 is not particularly limited, and various sensors such as an optical type, a piezoelectric type, and a mechanical type can be used.

  The air pressure supply pipe 8 has one end connected to a compressor (not shown) and the other end connected to the air spring 6 via a surge tank 15 and a leveling control valve 16. The control valve 16 has each port communicating with the surge tank 15 and the air spring 6 and another one port, and an exhaust pipe 17 is connected to the other one port. The leveling control valve 16 communicates the port on the surge tank 15 side and the air spring 6 side by valve control, and also connects the port on the exhaust pipe 17 and the port on the air spring 6 side and the exhaust pipe 17 side. At the same time, it is possible to switch the state of closing the port on the surge tank 15 side.

Moreover, the controller 11 which receives the detection result of the above-mentioned height sensor 10 is provided, and this controller 11 is comprised so that the said switching of the said leveling control valve 16 may be controlled based on the said detection result. The controller 11 can be constituted by, for example, a CPU, a program for operating the CPU, and a drive circuit that generates a signal for driving the leveling control valve 16.
In the controller 11, a threshold value is set such that the clearance between the lower surface of the loading platform 4a and the elastic stopper 9 in a normal state is 30 to 50 mm, and leveling control is performed according to three conditions “above, inside, and below” with respect to the threshold value. The valve 16 is set to open and close.

Hereinafter, the leveling control procedure of the loading platform will be described with reference to FIG.
The leveling control can be performed, for example, when the engine is stopped when the vehicle is stopped, and the detection result of the height sensor 10 is output to the controller 11 when the control is started (step s1). In the controller 11, the upper threshold value (50 mm) and the lower threshold value (30 mm) are set in advance as described above, and the determination is made whether the measured value is inside the threshold value or greater than the upper threshold value and less than or equal to the lower threshold value. Is made. If the measured value is within the upper and lower threshold values, leveling control is not necessary, and the control routine is terminated (step s2). On the other hand, if the measured value is not within the threshold value, the process proceeds to step s4 if the measured value is greater than or equal to the upper threshold value, and the process proceeds to step s5 if the measured value is less than or equal to the lower threshold value (step s3).

  When shifting to step s4, since the loading platform bottom 4a is at a position higher than the predetermined height, in step 4, it is necessary to lower the loading platform 4 and adjust the leveling to a height within a predetermined range. Therefore, the controller 11 controls the leveling control valve 16 to close the port on the surge tank 15 side so that the port on the air spring 6 side communicates with the port on the exhaust pipe 17 side. Thereby, the air in the air spring 6 is discharged out of the air spring 16 through the leveling control valve 16 and the exhaust pipe 17. The amount of air to be discharged (pneumatic control of the air spring) can be determined by the control time of the leveling control valve 16 and the like, so that the loading platform 4 can be leveled within the above threshold. An appropriate value such as the center of the threshold can be set as the target value at this time. After execution of step s4, the process returns to step s1, the height of the loading platform 4 is detected again, and it is confirmed that the height of the loading platform 4 is within a predetermined range, and then the control is terminated. At this time, if the height of the loading platform 4 is not within the predetermined range, the above procedure is repeated.

  On the other hand, when the process proceeds to step s5, since the loading platform 4 is in the lower position outside the threshold value, in step s5, the loading platform 4 is raised and positioned within a predetermined range. That is, the controller 11 controls the leveling control valve 16 to close the port on the exhaust pipe 17 side, and to connect the port on the surge tank 15 side and the port on the air spring 6 side. The surge tank 15 stores compressed air having a predetermined pressure by a compressor (not shown), and the compressed air is supplied from the surge tank 15 to the air spring 6 under the control of the leveling control valve 16. The amount of air supplied to the air spring 6 can be determined by the control time of the leveling control valve 16 and the like, so that the loading platform 4 can be raised and leveling can be adjusted within the above threshold. As the target value at this time, an appropriate value such as the center of the threshold can be set. After execution of step s5, the process returns to step s1, the height of the loading platform 4 is detected again, and it is confirmed that the height of the loading platform 4 is within a predetermined range, and then the control is terminated. At this time, if the height of the loading platform 4 is not within the predetermined range, the above procedure is repeated.

  By the above control, the level of the loading platform in the front-rear direction can be maintained regardless of the weight of the load. It is desirable that the above control is performed independently for the left and right air springs. This is because if there is a difference in the load sharing of the load in the left and right direction of the vehicle, the loading platform will tilt in the left and right direction, and the level of the loading platform in the left and right direction will be maintained by adjusting the left and right respectively Can do.

(Embodiment 3)
In the above-described embodiment, the description has been given of the structure in which the bottom of the loading platform has a vibration isolation structure with respect to the chassis frame. However, the present invention is not limited to the above-described configuration, and can be configured to prevent vibration of the floor pan even in a truck having an independent floor pan in the loading platform on which the load is loaded. The embodiment will be described with reference to FIG. In addition, about the structure similar to the said Embodiment 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted or simplified.

  In the third embodiment, a floor pan 20 is installed as a cargo bed floor on the chassis frame 2 in the cargo bed 4. The front end portion side of the floor pan 20 is attached to the chassis frame 2 so as to be rotatable only in the pitching direction by the hinge 5, and the rear end portion side of the floor pan 20 is the chassis frame 2 as in the above embodiment. An air spring 6 and a shock absorber 7 are interposed therebetween. In this embodiment, functions related to vibration isolation and posture maintenance of the floor pan are the same as in the above-described embodiment, and the load loaded on the floor pan is supported by the vibration isolation structure including the hinge 5 and the air spring 6. The structure is such that vibration is difficult to be transmitted, and the posture is stabilized by being mechanically restrained by the hinge 5. In addition, in the said embodiment, although the floor pan 20 shall be installed on the chassis frame 2, for example, the floor pan 20 may be attached on the loading platform bottom part as a chassis base part.

(Embodiment 4)
Next, an embodiment using a shock absorber 30 that exhibits nonlinear elasticity instead of the shock absorber 7 in the above embodiment will be described. The embodiment will be described with reference to FIGS. In addition, about the structure similar to the said Embodiment 1-3, the same code | symbol is attached | subjected and the description is abbreviate | omitted or simplified.
In this embodiment, as shown in FIG. 9, in place of the shock absorber 7, a shock absorber 30 is disposed in parallel with the air spring 6 between a floor pan 20 as a cargo bed floor and a chassis frame 2 as a chassis base. Is intervened. The shock absorber 30 is made of anti-vibration rubber as shown in detail in FIG. 10, and the upper side is attached to the floor pan 20 via an attachment plate 32a and the lower side is attached to the chassis frame 2 via an attachment plate 32b. Yes. The shock absorber 30 is formed with an internal gap 31 slightly above the central portion in the height direction, and a small cross-sectional portion 30a having a reduced cross-sectional area is formed around the internal gap 31. The lower side of the small cross-section portion 30a has no internal gap and constitutes a large cross-section portion 30b.
With the above configuration, the shock absorber 30 exhibits a small spring coefficient corresponding to the cross-sectional area of the small cross section 30a in a small displacement area where the small cross section 30a is deformed, and a large displacement after the small cross section 30a is completely displaced. In the region, a large spring coefficient corresponding to the cross-sectional area of the large cross section 30b is shown.
In this embodiment, the elastic stopper 9 provided in each of the embodiments is omitted.

The effect | action in this form is demonstrated.
Also in this embodiment, by introducing air into the air spring 6, the floor pan 20 is lifted up and supported by the air spring 6 and the shock absorber 30 to have a predetermined gap with respect to the chassis frame 2. When a pitching phenomenon occurs on the loading platform space side due to the traveling of the truck 1, the front side of the loading platform 4 rotates only in the vehicle pitching direction with respect to the chassis frame 2 by the hinge 5, and the rear side of the loading platform is the air spring 6 and the shock absorber. The vibration caused by pitching is effectively reduced by 30. At this time, the floor pan 20 is lifted up by the air spring 6, and the shock absorber 30 is elastically deformed mainly in the small cross section 30a without closing the internal gap 31, and in a small displacement range. A small spring coefficient is exhibited, and a very soft spring characteristic is realized. As a result, a resonance damping function works by the shock absorber 30 and vibration at the resonance frequency can be suppressed (at the resonance frequency, the amplitude is increased, the spring characteristic is hardened, and the attenuation is increased). At this time, since the spring characteristics of the shock absorber 30 are sufficiently low, the vibration isolation effect is not lowered by significantly increasing the resonance frequency of the vibration isolation structure.

  In addition, when the air spring 6 loses its air pressure and the elastic force of the air spring does not act, when the large amount of displacement acts on the shock absorber 30 and the amount of displacement increases, the internal space 31 is lost and The floor pan 20 is supported by the large cross section 30b in close contact. As a result, the anti-vibration rubber exhibits a large spring coefficient inherent to the rubber and supports the floor pan 20 in a hard elastic state. Even in this state, since the floor pan is secured to the shock absorber, it also has a function of preventing the floor pan from excessively moving when the air pressure is lost.

In addition, in the configuration in which the elastic stopper is provided as in the above embodiment, in order to ensure the stroke of the air spring, there is a clearance (about 30 mm) between the cargo bed floor portion and the elastic stopper, and when the cargo handling work is performed, etc. There is a problem that the cargo bed floor cannot maintain the original horizontal state by removing the air pressure of the air spring. In addition, since the loading platform floor is not fixed in a state where it just sits on the stopper, the loading platform floor cannot be restrained if the air pressure is lost for some reason. The floor may vibrate greatly and damage the cargo. On the other hand, in the present embodiment, the shock absorber 30 functions as a damper and a stopper as described above, so that the above problem can be solved by omitting the elastic stopper. Further, even when the shock absorber 30 functions as a stopper, the floor pan and the chassis frame 2 are maintained in a state where they are coupled by the shock absorber 30, so that vibration of the floor pan is suppressed.
FIG. 11 is a diagram showing an example of the load-displacement characteristics of the shock absorber 30. When the load is supported by the air spring, the load acting on the shock absorber 30 is close to zero, so that the spring characteristic is low, and the spring characteristic is tuned so that the spring characteristic is high when the air pressure that supports the load is lost. Has been.

(Embodiment 5)
In the said embodiment, the case where a nonlinear shock absorber is interposed between a loading platform floor part and a chassis base part is demonstrated. In the present invention, in addition to this, it is possible to provide a detachable coupling mechanism that temporarily rigidly couples the rear side of the cargo bed floor and the chassis base.
This embodiment will be described with reference to FIGS.
The shock absorber 35 used in this embodiment has non-linear elasticity, like the shock absorber 30 of the above embodiment, and exhibits a small spring coefficient with a small amount of displacement and a large spring coefficient with a large amount of displacement. A graph showing the relationship between the load and displacement characteristics of the shock absorber 35 is shown in FIG. The shock absorber 35 is tuned for non-linear characteristics depending on the shape, material characteristics, and the like.

  The shock absorber 35 is attached to the floor pan 20 on the upper side via the bracket 41 and attached to the chassis frame 2 on the lower side via the bracket 42. The bracket 42 has rising portions located on both sides of the shock absorber 35 and the bracket 41, and the rising portion has a height that allows the elastic deformation region of the shock absorber 35 to be secured. It is set to have a predetermined gap from the upper surface of 42. The rising portions are formed with connecting through holes 42a and 42a, respectively, while the bracket 41 is connected to the connecting through holes 42a and 42a so as to communicate with the connecting through holes 41a. The connecting pin 43 is prepared for rigidly connecting the floor pan 20 and the chassis frame 2 through the brackets 41 and 42 through the connecting through holes 42a, 41a and 42a. In this rigid coupling mechanism, the shape and material characteristics are selected so that sufficient strength can be obtained in consideration of the load applied to the cargo bed floor.

In this embodiment, by removing the connecting pin 43 at the time of vibration isolation, the vibration isolation function by the air spring 6 and the shock absorber 35 is obtained as in the above embodiment, and the air pressure of the air spring 6 is lost. In such a case, the floor pan 20 is supported by the non-linear spring characteristics of the shock absorber 35.
Further, when the floor pan 20 is more securely fixed at the time of cargo handling work or the like, the floor pan 20 is lifted up to an appropriate position by the air spring 6 and the connecting through holes 41a of the brackets 41 and 42, The connecting pin 43 is inserted in a state in which 42a is at the same height. When the work is performed thereafter, the air pressure in the air spring 6 may be released to the atmospheric pressure, or the work may be performed as it is.

In order to make the vibration isolation mechanism function from this state, the floor pan is lifted up again by the air spring 6, the height is adjusted so that the load applied to the connecting pin 43 becomes zero, and the connecting pin 43 is pulled out. Thus, the floor pan 20 is supported by the air spring 6 and the vibration isolation mechanism is effective.
In this state, since the spring characteristic of the air spring 6 and the spring characteristic of the shock absorber 35 act in parallel, the spring characteristic changes in a harder direction than the case of the air spring 6 alone, but the vibration-proof rubber used for the shock absorber 35 Since the spring characteristic is sufficiently low due to non-linear elasticity, the resonance frequency of the anti-vibration structure is greatly increased, and the anti-vibration effect does not deteriorate.

  Further, at the resonance frequency of the vibration isolating structure, the shock absorber 35 is damped by rubber and has a function as a damper. Further, when high-pressure air is not supplied to the air spring, the force in the vertical direction is supported by the non-linear large spring characteristics of the shock absorber 35. Therefore, even in this state, the floor pan is secured to the shock absorber 35. The floor pan also has a function of preventing excessive movement of the floor pan when air pressure is lost.

In the fourth and fifth embodiments, the description has been given of the one having the floor pan as the loading platform floor portion, but it is naturally possible to apply these embodiments to a truck having no floor pan.
As described above, the present invention has been described based on each embodiment, but the present invention is not limited to the description of the above embodiment, and can be appropriately changed without departing from the scope of the present invention. .

It is a side schematic diagram showing one embodiment of the present invention. Similarly, it is a partially enlarged perspective view showing a rotational mounting state in front of the loading platform. Similarly, it is a top view which shows the chassis frame and loading platform by the loading platform space side. Similarly, it is a partially expanded side view which shows the elastic attachment of the loading platform rear side. It is a partially expanded side view which shows the loading platform rear side in other embodiment of this invention. Similarly, it is a flowchart which shows the leveling control procedure of a loading platform. It is the side surface schematic diagram which shows other embodiment of this invention. It is a graph which shows the vibration distribution in a track. It is the side surface schematic diagram which shows other embodiment of this invention. Similarly, it is front sectional drawing which shows the shock absorber which has nonlinear elasticity. Similarly, it is a graph showing the relationship between the load and displacement characteristics of a shock absorber having nonlinear elasticity. It is the side surface schematic diagram which shows other embodiment of this invention. Similarly, it is a perspective view which shows the shock absorber which has nonlinear elasticity, and a rigid connection mechanism. Similarly, it is a perspective view which shows the attachment state of the shock absorber which has nonlinear elasticity, and a rigid connection mechanism. Similarly, it is a graph showing the relationship between the load and displacement characteristics of a shock absorber having nonlinear elasticity.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Truck 2 Chassis frame 3 Cab 4 Loading platform 4a Loading platform bottom 5 Hinge 6 Air spring 7 Shock absorber 8 Air pressure supply piping 9 Elastic stopper 10 Height sensor 11 Controller 15 Surge tank 16 Leveling control valve 17 Exhaust pipe 20 Floor pan 30 Shock absorber 35 Shock Absorber 40 Rigid connection mechanism 41 Bracket 42 Bracket 43 Connection pin

Claims (7)

  A truck bed anti-vibration structure having a loading platform space behind the cab and a loading platform floor installed on a chassis base on the loading platform space side, wherein the front side of the loading platform floor is pitched to the chassis base A truck bed vibration-proof structure, wherein the truck bed is pivotably attached only in a direction and the rear side of the bed floor is elastically attached to the chassis base.   2. The truck bed anti-vibration structure according to claim 1, wherein a rear side of the bed floor is elastically attached to the chassis base through a gas spring.   3. The truck load-carrying vibration isolating structure according to claim 2, wherein a shock absorber is interposed in parallel with the gas spring between the load carrier floor part and the chassis base part.   A sensor that measures the distance between the cargo bed floor and the chassis base, a gas supply source that supplies gas to the gas spring, a gas control valve that controls gas movement of the gas spring, and an output from the sensor And a gas pressure control means for controlling the gas pressure of the gas spring by controlling the gas control valve so that the distance between the loading platform and the loading platform floor portion when stationary is a predetermined distance. The truck bed vibration-proof structure according to claim 2 or 3, characterized in that:   The truck load-carrying vibration isolating structure according to any one of claims 1 to 4, further comprising an elastic stopper that prevents the cargo bed floor portion and the chassis base portion from approaching each other at a predetermined distance or more.   In the elastic mounting, a shock that exhibits nonlinear elasticity between the rear side of the cargo bed floor and the chassis base is small when the amount of displacement is small and the spring coefficient is large when the amount of displacement is large. The truck bed vibration-proof structure according to claim 1 or 2, wherein an absorber is interposed.   7. A truck bed vibration isolating structure according to claim 1, further comprising a detachable coupling mechanism for temporarily rigidly coupling the rear side of the bed floor and the chassis base. .

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