JP6754855B2 - Suspension device - Google Patents

Description

The present invention relates to a suspension device for suspending traveling elements such as wheels and crawlers on a vehicle body, and more particularly to a suspension device for suppressing a change in posture of the vehicle body.

In a conventional suspension device, each traveling element is usually suspended on a vehicle body by using a single spring in order to make each traveling element follow the unevenness of the road surface. Therefore, the deflection of the spring with respect to the load from the vehicle body becomes a linear characteristic, and when the load from the vehicle body changes, it expands and contracts and the posture of the vehicle body changes.

By the way, a work vehicle having front wheels and rear wheels as traveling elements in a vehicle body and traveling by supporting a work device at the rear portion of the vehicle body so as to be able to move up and down is known by, for example, Patent Document 1, which is described in Patent Document 1. In a work vehicle, the suspension device that suspends the front wheels on the vehicle body has an expansion / contraction sensor, the vehicle body has a front-rear tilt sensor, and the elevation control unit that controls the elevation of the work device uses the detection values of the expansion / contraction sensor and the front-rear tilt sensor. Based on this, even if the vehicle body is inclined due to unevenness of the road surface or the like, the work device is maintained at a constant height to perform stable work.

JP-A-2018-166485

However, this conventional work vehicle has a disadvantage that the sensor and the control system are expensive and the manufacturing cost is high, and the structure is complicated and the maintenance cost is also high.

Further, in this conventional work vehicle, although the work device can be maintained at a constant height, the suspension device expands and contracts in order to make the front wheels follow the unevenness of the road surface while the vehicle is running, and the load on the vehicle body is increased. Since the suspension device expands and contracts due to changes, there is an inconvenience that it is difficult to maintain the vehicle body itself in a constant posture such as horizontal.

Therefore, the present invention provides a suspension device capable of maintaining a constant posture of a vehicle having traveling elements on the vehicle body and allowing those traveling elements to follow the unevenness of the road surface with a simple and inexpensive configuration. The purpose.

The suspension device of the present invention that advantageously solves the above problems
It suspends each traveling element on the body of the vehicle.
It includes a suspension arm that supports the traveling element on the vehicle body so as to be able to bounce and rebound, and a spring structure that is inserted between the traveling element and the vehicle body.
The spring structure
A first load applied to the traveling element from the vehicle according to the maximum load of the vehicle is fully extended in a pre-applied state, and elastically compressed when a load exceeding the first load is applied. The first spring to be done and
A second spring that is fully compressed by a second load applied to the traveling element from the vehicle according to the minimum load of the vehicle, and is elastically stretched when the applied load becomes smaller than the second load. When,
There is constituted coupled in series,
As a result, the spring structure maintains a constant length with respect to the load between the first load and the second load applied from the vehicle to the traveling element, and maintains the vehicle body in a constant posture. It is characterized by that.

In the suspension device of the present invention, while the suspension arm supports each traveling element to the vehicle body so as to be able to bounce and rebound, and the vehicle is loaded with a load between the minimum load and the maximum load. , The first spring of the spring structure inserted between those traveling elements and the vehicle body is fully extended and the second spring is fully compressed, so that the spring structure maintains a constant length and the vehicle body is For example, maintain a constant posture such as a horizontal state.

Then, while the vehicle is traveling in this state, when any traveling element rides on, for example, a convex portion of the road surface, and a load exceeding the first load corresponding to the maximum load is applied from the traveling element to the corresponding spring structure. , The first spring is compressed from the fully extended state to maintain the contact state with the road surface while absorbing the impact on the vehicle body due to the riding of the traveling element alone on the convex part of the road surface, and the other traveling elements are still flat. If it is on a smooth road surface, the spring structure corresponding to other traveling elements maintains a constant length, and the vehicle body is maintained in a constant posture such as a horizontal state.

Further, when one of the traveling elements enters the recess of the road surface while the vehicle is traveling and the load applied from the traveling element to the corresponding spring structure becomes smaller than the second load corresponding to the minimum load, the second load is obtained. The spring extends from the fully compressed state, and the traveling element enters the recess of the road surface to support the vehicle body with the traveling element while maintaining the contact state with the road surface, and the other traveling elements are still on the flat road surface. If so, the spring structure corresponding to other traveling elements maintains a constant length, and the vehicle body is maintained in a constant posture such as a horizontal state.

Therefore, according to the suspension device of the present invention, the posture of the vehicle body having the traveling elements on the vehicle body is maintained constant and the traveling elements are placed on the road surface by a simple and inexpensive configuration that does not depend on the sensor or the control system. It can follow the unevenness.

In the suspension device of the present invention, at least one of the first spring and the second spring is configured by connecting a plurality of springs in series and / or in parallel. In the case of series, for example, One spring is fully compressed as the load increases and then the other spring is started to compress, or one spring is fully extended as the load decreases and then the other spring. It is preferable because the elastic ratios of the plurality of springs can be set differently so that the springs start to extend. Further, in the case of parallel, it is preferable because a plurality of thin springs having a total predetermined strength can be arranged side by side in a narrow accommodation space, and the degree of freedom in the configuration of the suspension device can be increased.

Further, in the suspension device of the present invention, when one or a plurality of springs constituting at least one of the first spring and the second spring includes a gas spring, the vehicle body due to the damping characteristic of the gas spring. It is preferable because it can suppress the vibration and sudden change in posture.

It is a side view which shows typically the vehicle which includes the suspension device of two embodiments of this invention. (A) to (c) are cross-sectional views showing the spring structure of each of the suspension devices of the above two embodiments in a rebound posture, a basic posture, and a bound posture. It is a characteristic diagram which shows the operation characteristic of the said spring structure. (A) and (b) are plan views and side views showing the operating states of the suspension devices of the two embodiments when one of the left and right front wheels of the vehicle enters the recess of the road surface, respectively. (A) and (b) are a plan view and a side view showing the operating state of the suspension device of the two embodiments when one of the left and right rear wheels of the vehicle enters the recess of the road surface, respectively. (A) and (b) are operating states of the suspension devices of the above two embodiments when one of the left and right front wheels of the vehicle rides on a step on the road surface and when one of the left and right rear wheels rides on a step on the road surface. It is a side view which shows each. (A) to (c) are cross-sectional views showing a spring structure of each of the suspension devices of the other two embodiments of the present invention in a rebound posture, a basic posture, and a bound posture. It is a characteristic diagram which shows the operation characteristic of the said spring structure.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, FIG. 1 is a side view schematically showing a vehicle including the suspension devices of the two embodiments of the present invention, and the vehicle carries, for example, articles, appliances, and the like to assist human work. The base of the lower part of the vehicle body 1 so that the vehicle body 1, the four wheels 2 as each running element in which the motor is housed in the wheels on which the tires are mounted, and the four wheels 2 are located at the four corners of the vehicle body 1. The front wheel suspension device 3 and the rear wheel suspension device 4 as the above two embodiments suspended from the frame 1a are provided.

Although not shown, the vehicle body 1 has a loading space at the top, a battery and a control device are housed inside, and a camera for image recognition around the front of the vehicle body 1 is mounted at the front portion. Equipped with a normal computer, based on a program given in advance, the motors in the wheels of each wheel 2 are operated while checking the situation around the front of the vehicle body 1 with the image from the camera at the front of the vehicle body 1. As a result, for example, as shown by the arrow F in FIG. 1, the vehicle travels together in the forward direction to the left in the figure at a relatively low speed on a relatively flat road surface R, for example, after the operator.

As shown by the arrow E, the front wheel suspension device 3 expands and contracts to support each wheel 2 as a front wheel on the base frame 1a of the vehicle body 1 so as to bounce and rebound, and the strut type suspension arm 3a, each wheel 2 and the vehicle body. It is provided with a spring structure 5 inserted between and 1 and the rear wheel suspension device 4 can swing as shown by an arrow S to bounce and rebound each wheel 2 as a rear wheel. It is provided with a trailing arm type suspension arm 4a supported on the base frame 1a of the vehicle body 1 and a spring structure 5 interposed between each wheel 2 and the vehicle body 1.

Although the structure of the spring structure 5 of the front wheel suspension device 3 and the spring structure 5 of the rear wheel suspension device 4 are the same as each other, the spring structure 5 of the front wheel suspension device 3 and the rear wheel suspension device The spring constants of 4 with the spring structure 5 are individually set according to the magnitude of the load applied from the vehicle body 1 to the front wheel suspension device 3 and the rear wheel suspension device 4, including the case where they are the same.

2 (a) to 2 (c) are cross-sectional views showing the spring structure 5 of each of the suspension devices of the above two embodiments in a rebound posture, a basic posture, and a bound posture, and is a front wheel suspension device 3. The spring structure 5 having the same configuration as that of the rear wheel suspension device 4 is composed of, for example, a box-shaped casing 6 and a gas spring in these embodiments, as shown in the rebound posture of FIG. 2A. The first spring 7 has a first spring 7 and a second spring 8, and the first spring 7 has a main body 7a and a piston 7b that moves while passing gas under a pressing force of a pressure receiving area difference of the gas in the main body 7a. It has a rod 7c that is driven by the piston 7b and elastically and gently extends from the main body 7a. Similarly, the second spring 8 also presses the main body 8a and the difference in the pressure receiving area of the gas in the main body 8a. It has a piston 8b that receives and moves while passing gas, and a rod 8c that is driven by the piston 8b and elastically and gently extends from the main body 8a. The first spring 7 and the second spring 8 are the main body 7a. , The preload and elastic force can be arbitrarily set by adjusting the pressure of the gas sealed in 8a or changing the cross-sectional areas of the main bodies 7a, 8a and the pistons 7b, 8b.

The main bodies 7a and 8a are fixedly housed in the casing 6, and the rod 7c protrudes upward and backward from the casing 6 when no load is applied, and the rod 8c advances and retreats downward from the casing 6 when no load is applied. It protrudes so that it can be moved.

Further, as shown in FIG. 1, the first spring 7 is added to each wheel 2 from the vehicle body 1 in a state where the spring structure 5 is attached to the front wheel suspension device 3 and the rear wheel suspension device 4. The first load as the preload corresponding to the maximum load of the above is fully extended in a state of being given in advance, and when a load exceeding the first load is applied from the wheel 2, the rod 7c is moved into the main body 7a. It is retracted toward and elastically compressed.

Further, as shown in FIG. 1, the second spring 8 is added to each wheel 2 from the vehicle body 1 in a state where the spring structure 5 is attached to the front wheel suspension device 3 and the rear wheel suspension device 4. When the load reaction force applied from each wheel 2 becomes smaller than the second load, the rod 8c is moved out of the main body 8a to be elastically compressed by the second load corresponding to the minimum load of the wheel 2. It is stretched.

By arranging and fixedly accommodating the main bodies 7a and 8a of the first spring 7 and the second spring 8 in the casing 6, the first spring 7 and the second spring 8 are mechanically substantially in series in the direction of the load from the vehicle body 1. Is bound to.

FIG. 3 is a characteristic diagram showing the operating characteristics of the spring structure 5 when mounted on the front wheel suspension device 3 and the rear wheel suspension device 4, and FIGS. 4 (a) and 4 (b) are the above-mentioned vehicles. 5 (a) and 5 (b) are plan views and side views showing the operating states of the suspension devices of the above two embodiments when one of the left and right front wheels of the vehicle enters the recess of the road surface. The plan view and side view showing the operating state of the suspension device of the above two embodiments when one of the left and right rear wheels enters the recess of the road surface, FIGS. 6 (a) and 6 (b), show the vehicle. It is a side view which shows the operating state of the suspension device of the said two embodiments when one of the left and right front wheels rides on a step on a road surface, and when one of the left and right rear wheels rides on a step on a road surface.

That is, in the suspension devices of the above two embodiments, the load applied to the spring structure 5 is an article or device having a weight within the range from the minimum load to the maximum load of the vehicle, as shown in the central portion of FIG. When the spring structure 5 is within the range A when traveling on an ideal flat road with a load such as, the spring structure 5 is a second spring 8 on the rebound side as shown in the basic posture of FIG. 2 (b). Is fully compressed and the first spring 7 on the bound side continues to be fully extended.

Then, from the above basic posture, as shown in FIGS. 4A and 4B, both the front wheels and the rear wheels 2 come into contact with the road surface R at the support point H, and the center of gravity G of the vehicle body 1 is set. In the supported state, the other wheel 2 of the front wheel enters the recess P, and the load reaction force applied from the wheel 2 to the spring structure 5 is within the range C smaller than the second load, which is the lower limit of the range A in FIG. Then, the spring structure 5 takes the rebound posture shown in FIG. 2A, and the second spring on the rebound side of the spring structure 5 of the front wheel suspension device 3 is increased by the length corresponding to the magnitude of the reduced load. The rod 8c is elastically extended by advancing the rod 8c out of the main body 8a, and the wheel 2 of the wheel 2 is supported on the vehicle body 1 by the wheel 2 by entering the recess P of the road surface R. If the contact state is maintained and the other wheels 2 are still on the flat road surface R, the vehicle body 1 is maintained in a constant posture such as a horizontal state.

Further, from the above basic posture, as shown in FIGS. 5A and 5B, both the wheels 2 of the rear wheels and the front wheels come into contact with the road surface R at the support point H, and the center of gravity G of the vehicle body 1 is set. In the supported state, the other wheel 2 of the rear wheel enters the recess P, and the load reaction force applied to the spring structure 5 from the wheel 2 is within the range C smaller than the lower limit of the lower limit of the range A in FIG. Then, the spring structure 5 takes the rebound posture shown in FIG. 2 (a), and the rebound side of the spring structure 5 of the rear wheel suspension device 4 is increased by the length corresponding to the magnitude of the reduced load. The 2 spring 8 advances the rod 8c out of the main body 8a and is elastically extended, and the wheel 2 enters the recess P of the road surface R to support the vehicle body 1 with the wheel 2 and the wheel to the road surface R. If the contact state of 2 is maintained and the other wheels 2 are still on the flat road surface R, the vehicle body 1 is maintained in a constant posture such as a horizontal state.

On the other hand, from the above basic posture, as shown in FIGS. 6A and 6B, one of the left and right wheels 2 of the front wheel or the rear wheel rides on the step S as a convex portion to form the spring structure 5. When a load in the range B exceeding the upper limit of the upper limit of the range A in FIG. 3 is applied from the wheel 2, the spring structure 5 is in the bound state shown in FIG. 2 (c), and the magnitude of the load is increased. The first spring 7 on the bounce side of the spring structure 5 of the front wheel suspension device 3 or the rear wheel suspension device 4 is elastically compressed by retracting the rod 7c toward the inside of the main body 7a by the corresponding length. If the wheel 2 is in contact with the road surface R while absorbing the impact on the vehicle body 1 due to the wheel 2 riding on the step S of the road surface R, and the other wheels 2 are still on the flat road surface R. , The vehicle body 1 is maintained in a constant posture such as a horizontal state. Then, after the wheel 2 gets over the step S, the spring structure 5 gradually shifts to the basic posture shown in FIG. 2B due to the damping characteristic of the first spring 7, so that the vehicle body 1 has a sudden posture. Change can be suppressed.

Therefore, in any of the front wheel suspension device 3 and the rear wheel suspension device 4, the vehicle having the wheels 2 on the vehicle body 1 maintains the posture of the vehicle body 1 while traveling, and the wheels 2 on the unevenness of the road surface R. The follow-up can be sufficiently maintained.

Moreover, in both the front wheel suspension device 3 and the rear wheel suspension device 4, the first spring 7 and the second spring 8 are both composed of gas springs having damping characteristics, and therefore, due to the damping characteristics, It is possible to suppress vibration of the vehicle body 1 and sudden changes in posture.

7 (a) to 7 (c) show a rebound posture and a basic spring structure 5 of each of the front wheel suspension device 3 and the rear wheel suspension device 4 as the suspension devices of the other two embodiments of the present invention. It is sectional drawing which shows the posture and the bound posture.

The suspension devices of the other two embodiments described above are the suspension devices of the two embodiments of the former, that is, the former in that they constitute the suspension device 3 for the front wheels and the suspension device 4 for the rear wheels. Although they are the same, the spring structure 5 that each of the suspension devices of the latter two embodiments has is different from that of the suspension devices of the former two embodiments, as shown in FIGS. 7 (a) to 7 (c). Unlike the spring structure 5, the first spring 7 and the second spring 8 both accommodate one coil spring 7d, 8d in the main bodies 7a, 8a of the gas spring.

The coil spring 7d is arranged in the main body 7a of the gas spring on the side opposite to the rod 7c side with respect to the piston 7b, and the upper end portion is fixed to the piston 7b in the figure. In the figure of the main body 7a of the gas spring, a predetermined gap is provided between the gas spring and the lower end portion. The coil spring 7d may be fixed to the lower end side of the main body 7a of the gas spring. As a result, as shown in FIG. 7C, when the piston 7b descends above a predetermined position, the coil spring 7d is compressed by a length corresponding to the descending distance of the piston 7b from the predetermined position, and its spring constant The elastic force corresponding to the compression length is applied to the rod 7c according to the above.

The coil spring 8d is arranged in the main body 8a of the gas spring on the side opposite to the rod 8c side with respect to the piston 8b, and the lower end portion is fixed to the piston 8b in the figure. In the figure of the main body 8a of the gas spring, a predetermined gap is provided between the gas spring body 8a and the upper end portion. The coil spring 8d may be fixed to the upper end side of the main body 8a of the gas spring. As a result, as shown in FIG. 7B, when the piston 8b rises above a predetermined position, the coil spring 8d is compressed by a length corresponding to the rising distance of the piston 8b from the predetermined position, and its spring constant The elastic force corresponding to the compression length is applied to the rod 8c according to the above.

FIG. 8 is a characteristic diagram showing the operating characteristics of the spring structure 5, even though the characteristics of the spring structure 5 of the suspension devices of the above two embodiments under load B and load C are linear. On the other hand, in the spring structure 5 each of the suspension devices of these two embodiments, the characteristics under the load B and the load C are broken.

That is, the first spring 7 is compressed only by the elastic force of the gas spring in the range of the load B1, and the elastic force of the gas spring and the elastic force of the coil spring 7d are added in the range of the load B2 exceeding the load B1. It is compressed with. As a result, when the wheel 2 travels on the uneven surface, when the wheel 2 first collides with the concave or convex surface, the suspension collides with the suspension in a soft state (the spring constant of the first spring 7 is low), so that the impact of the collision is impacted. After the collision, the suspension is stiff (the spring constant of the first spring 7 is high) and the displacement of the vehicle body 1 is small, so that the posture during running is stable.

Further, the second spring 8 is compressed by a force obtained by adding the elastic force of the gas spring and the elastic force of the coil spring 8d in the range of the load C1, and is compressed only by the elastic force of the gas spring in the range of the load C2 smaller than the load C1. It is compressed. As a result, when the wheel 2 travels on the uneven surface, when the wheel 2 enters the concave surface, the suspension is in a hard state (the spring constant of the second spring 8 is high), so that the wheel 2 quickly descends along the concave surface. After that, the suspension becomes soft (the spring constant of the second spring 8 is low), so that the impact on the wheel 2 when exiting the concave surface is small.

Although the above description has been made based on the illustrated embodiment, the present invention is not limited to the above-described embodiment, and can be appropriately changed as necessary within the scope of the patent claim. At least one of the first spring 7 and the second spring 8 in the suspension device of the present invention may use a normal coil spring or a rubber-like elastic body that elastically expands and contracts instead of the gas spring, in which case the coil spring. A damper may be installed in the spring to absorb the vibration.

Further, each of the first spring 7 and the second spring 8 in the suspension device of the latter two embodiments is configured by connecting one gas spring and one coil spring in series, and these first springs. At least one of the 7 and the second spring 8 may be configured by connecting a gas spring and two or more coil springs in series, in which case the two or more coil springs have different spring constants. At the same time, if it is different from the gas spring, at least one of the first spring 7 and the second spring 8 of the spring structure 5 can have complicated operating characteristics according to the configuration of the suspension arm and the like. Further, at least one of the first spring 7 and the second spring 8 may be configured by connecting two or more thinner gas springs and two or more coil springs in parallel, in which case. Since a plurality of thin springs having a total predetermined strength can be arranged side by side in a narrow storage space, the degree of freedom in the configuration of the suspension device can be increased.

Further, the suspension arm of the suspension device of the present invention may be a leading arm type instead of the strut type for the front wheels, and is the first in the spring structure to be combined with the swinging suspension arm of the leading arm type or the trailing arm type. The 1st spring and the 2nd spring may be a torsion spring coupled to the swing shaft of their suspension arm.

Further, the traveling element on which the suspension device of the present invention is suspended may be a support wheel, a drive wheel, a guide wheel, or the like of a crawler (track).

Thus, according to the suspension device of the present invention, the posture of the vehicle body having the traveling elements on the vehicle body is maintained constant by a simple and inexpensive configuration that does not depend on the sensor or the control system, and the traveling elements are made uneven on the road surface. Can be made to follow.

1 Body 2 Wheels 3 Front wheel suspension device 4 Rear wheel suspension device 5 Spring structure 6 Casing 7 1st spring 7a, 8a Main body 7b, 8b Piston 7c, 8c Rod 7d, 8d Coil spring 8 2nd spring H Support point P recess R Road surface S Step

Claims (3)

In the suspension device that suspends each traveling element on the vehicle body
It includes a suspension arm that supports the traveling element on the vehicle body so as to be able to bounce and rebound, and a spring structure that is inserted between the traveling element and the vehicle body.
The spring structure
A first load applied to the traveling element from the vehicle according to the maximum load of the vehicle is fully extended in a pre-applied state, and elastically compressed when a load exceeding the first load is applied. The first spring to be done and
A second spring that is fully compressed by a second load applied to the traveling element from the vehicle according to the minimum load of the vehicle, and is elastically stretched when the applied load becomes smaller than the second load. When,
There is constituted coupled in series,
As a result, the spring structure maintains a constant length with respect to the load between the first load and the second load applied from the vehicle to the traveling element, and maintains the vehicle body in a constant posture. A suspension device characterized by the fact that. The suspension device according to claim 1, wherein at least one of the first spring and the second spring is configured by connecting a plurality of springs in series and / or in parallel. The suspension device according to claim 1 or 2, wherein at least one of the first spring and the second spring includes a gas spring.

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