JPS59193330A - Fatigue tester of cab - Google Patents

Abstract

PURPOSE:To realize magnitudes of shocks and frequencies simulating real operation with a comparatively small-capacity hydraulic cylinder by connection with a proper play a cab supporting truck and a piston rod. CONSTITUTION:Forward translation motions are provided to a wheeled truck 1 in an intermittent manner, by switching a solenoid change-over operating valve 25 with a timer 29, and switching a 3-position change-over valve 19 to a range between forward F and neutral N positions or between forward F and retarding R by advancing and retarding of piston rod 23 of air cylinder 21. At a joint of wheeled truck 1 and piston rod 11 shocks are generated onto the truck 1 when the piston rod 11 operates intermittently leaving a play 1b and thus shocks are given to a cab 7 on the truck simulating roughly real operation with a comparatively small-capacity hydraulic cylinder 9. Varied setting times of timer 29, amounts of strokes of hydraulic cylinder 9 and magnitudes of play 1b cause changes to oscillation mode and magnitude of shocks given to the cab 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a test device for evaluating the fatigue strength of a cab in a construction vehicle or an earthmoving vehicle.
There are two methods for evaluation: attaching the cab to an actual vehicle and operating it, or evaluating it in a test room by applying repeated tension and compression forces to the cab using a hydraulic cylinder; however, the former method does not involve operating an actual vehicle. A) A dedicated operator is required to operate the vehicle for a long time, which not only causes severe fatigue for the operator but also consumes a large amount of fuel. If it is small, it is impossible to generate an impact force equivalent to that during actual operation, and a large-capacity hydraulic system is required, and the impact force applied to the cab is only in the front and rear directions, which occurs during actual operation. 1. There is a drawback that it is not possible to apply a downward impact force, and evaluation must be performed under conditions that are considerably different from those in actual operation.

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and for this reason, the test device according to the present invention includes a bogie that supports a cab via an elastic member; and a piston rod that is connected with a play between the bogies. A hydraulic cylinder for moving the truck; a 6-position switching valve that controls the supply of pressure oil from the hydraulic pressure source to the hydraulic cylinder to extend, retreat, or stop the piston rod; A switching valve actuating means for controlling the position switching valve so that the piston rod moves backward toward the starting end of the stroke at the end of the forward stroke, and an operating time of the switching valve operating means is set. It is equipped with a control means including a timer (hydraulic pressure with a relatively smaller capacity than C), which applies a magnitude and frequency of impact force similar to that in actual operation with a cylinder, and simultaneously generates vertical vibration by excitation in the longitudinal direction. In the following, preferred embodiments of the present invention will be described. This will be explained with reference to the attached drawings.

The figure shows an example of the impact-type fatigue testing apparatus according to the present invention, and in the figure, 1 indicates a first trolley that moves on a horizontal floor surface, and the roller guides the trolley in a predetermined stroke path 5. 1
- and casters for preventing the cart from sliding laterally; 7 is a cab supported on the cart and whose fatigue strength is to be tested; 9 is a fixed hydraulic cylinder connected to the cart 1 at the end of the piston rod; 16 is a Oil tank, 15 is pump, 1
7 is a motor for operating the pump, 19 is a 6-position switching valve '' for controlling the supply of pressure oil from the oil tank 16 to the hydraulic cylinder 9, and 21 is a piston for controlling the valve spool position of the 6-position switching valve. an air cylinder connected to the rod 26 to the valve spool of the three-position switching valve 19;
5 is a two-position switching valve operated by a solenoid that controls the air pressure supply from the air pressure source 27 to the air cylinder 21; 29 is a timer for setting the solenoid operating time to control the switching time of the two-position switching valve; 61
Reference numeral 36 indicates a power supply for operating the timer, and 36 indicates a time-limited contact switch which is incorporated in the timer operating circuit 2 and is opened by a portion of the trolley 1 that is moved at the end of the stroke.

The cab 7 is supported on the truck 1 via an elastic material filter 5 such as a rubber mount, and as described later, the piston rod 11 of the hydraulic cylinder 9 is intermittently moved to support the cab 7 on the truck 1. When longitudinal vibrations are applied to the cab, downward vibrations are also applied to the cab at the same time, making it possible to provide vibrations close to those during actual operation.

Further, the connection between the truck 1 and the piston rod 11 is the sixth one.
As shown in the enlarged figure, when the piston rod 11 is moved intermittently by giving play or backlash 1b to the connecting portion 1a of the truck 1, an impact force is generated on the truck 1, thereby causing a relatively small amount of hydraulic pressure. The cylinder 9 can apply an impact force equivalent to the impact force y during actual operation to the cab 7 supported on the truck. As mentioned above, the backlash 1b formed in the connecting part 1a plays an extremely important role as a medium for propagating an impact force similar to the impact force during actual operation from the vibration source. As shown, the front end 1 of the connecting part 1a
d is closed and connected to the piston rod 11 via a connecting pin 16 at the play 1b of the connecting portion 1a.

Therefore, each time the piston rod 11 swings and moves intermittently, the connecting pin 16 collides with the t'IJ end 1d, transmitting subtle vibrations to the bracket side.

The play 1b is a notch 1- which is elongated in the longitudinal direction of the connecting portion 1a. Changing the length of the notch changes how vibrations are transmitted, so if the connecting part 1a is freely attached to the bracket 1C attached to the trolley 1 via the pin 18, the length of the notch will change. It is also a desirable feature of the present invention that the connecting portions 1a can be exchanged depending on their lengths and used, and that it is convenient for repair.

The six-position switching valve 19 is configured to project, retreat, or stop the piston rod 11 of the hydraulic cylinder 9 depending on the amount of protrusion of the piston rod 23 of the air cylinder 21. The amount of protrusion is determined by the "on" and "off" switching time of the solenoid-operated two-position switching valve 25, which is set by the timer 29. By selecting , the three-position switching valve 19 is moved between the forward position F and the neutral position N during the forward stroke of the truck 1.
Alternatively, the piston rod 1 can be moved between the forward position F and the backward position R in a desired switching time.
1 and concatenated thereto.

The stroke movement of the truck 1, that is, the vibration mode of the cab 7 on the truck 1, can be changed in various ways.

The time-limited contact switch 36 releases the timer operating circuit 62 for a set time [-1].
By keeping the position switching valve 19 inactive during that time,
is held in the retracted position R, thereby the piston rod 11
After the set time has elapsed to return the truck 1 connected thereto to the stroke starting end, the time limit contact switch 63 closes the timer operating circuit 62 again.

Next, to describe the operation of the test device having the above configuration, when the power (not shown) is turned on, the solenoid switching valve 2
5 is switched at the time interval set by the timer 29, thereby causing the air cylinder 21 to protrude and retract the piston rod 26 at a speed and stroke amount corresponding to the set time, thereby causing the 6-position switching valve 19 to The piston rod 26 is switched between the forward position F and the neutral position N or between the forward position F and the backward position R depending on the speed and stroke amount of the piston rod 26 (in the latter case, the time required to maintain the forward position is (a timer is set so that the time is longer than the amount of time it is held in the reverse position), the trolley 1 is intermittently moved forward, ie, to the left as viewed in the diagram. At this time, there is play or backlash in the connection between the truck 1 and the piston rod 11.
Since the position b is resting, a truck IK impact force is generated every time the piston rod 11 is moved intermittently, and this gives the cab 7 supported on the truck an impact force equivalent to V during actual operation. It will be done. At the same time, an elastic member 6 is attached to the cab 7.
Vibration in the vertical direction is applied by the support structure via 5. When the trolley 1 reaches the end of its stroke while repeating intermittent movement in this way, a part of the trolley moves to the time-limited contact switch 6.
3 and the timer operating circuit 62 is opened. As a result, the solenoid switching valve 25 is held in the non-operating position, the rear position switching valve 19 is moved to the retreat position R, and the truck 1 is moved toward the stroke starting end. Time-limited contact switch 6
After the timer operating circuit 62 is shut off, the timer operating circuit is closed again as the set time elapses, and the truck 1 moves forward again while moving intermittently at the time intervals set by the timer 29.
Do a loaf. The test is performed by repeating the above cycle a predetermined number of times. Note that by changing the set time of the timer 29, the stroke amount of the hydraulic cylinder 9, and the size of the backlash 1b at the connection between the piston rod 11 and the truck 1, the vibration mode and the size of the impact force applied to the cab 7 can be adjusted. It can be changed.

The stress frequency distribution during actual operation and the waveforms or frequencies of vibration acceleration in the vertical and horizontal directions change depending on the size of the cab and the composition of its component parts. By storing secondary items in CP(j), it is possible to easily reproduce a fatigue test that approximates actual operation while conducting a logical analysis with CPU. The connecting portion 1a is connected so that the
The backlash 1b is selected by 1(,9M).

As described above, according to the present invention, it is possible to apply an excitation mode close to the state during actual operation using a relatively small-capacity hydraulic system without causing operator fatigue or large amount of fuel consumption. Equipment is provided.

[Brief explanation of the drawing]

The first south diagram is a diagrammatic view showing an example of the device of the present invention, the second figure is a side view showing how the cab is supported on the truck, and the third figure is an enlarged perspective view showing the connection between the piston rod and the truck. It is. 1...Dolly 1a...Connection part 1b...
...Backlash 7...Cab 9...
・Hydraulic cylinder 11... Piston rod 13... Oil tank 19... Position switching valve 21... Air cylinder 26...
...Piston rod 25...2 position switching valve 2
7...Air pressure source 29...Timer
Ro2...Timer operation circuit 63...
Time-limited contact switch 35...Elastic member

Claims (1)

[Scope of Claims] (1) A truck capable of supporting a cab via an elastic member; A hydraulic cylinder for moving the truck to which a piston rod is connected with play;
or a position switching valve that controls the supply of pressure oil from a hydraulic source to a hydraulic cylinder in order to stop the piston rod; A cab fatigue testing device comprising a control means including a switching valve operating means for controlling the six-position switching valve to move the switching valve backward, and a timer operating circuit for setting an operating time of the switching valve operating means. (2) The switching valve actuation means includes an air cylinder having a piston rod connected to the six-position switching valve, and a solenoid actuator that controls the supply of air pressure from an air pressure source to the air cylinder to extend or retract the piston rod. 1. The device according to item 1, comprising a two-position switching valve. (3) The apparatus of claim 1, wherein the timer operating circuit includes a time-limited contact switch that is engaged by the truck to open the circuit for a predetermined period of time at the end of a forward stroke. (4) The device according to item 1, wherein the connecting portion interposed between the truck and the piston rod has a notch of an appropriate length so that the rod can be moved intermittently. (5) The device according to item 1, wherein the connecting portion of item @ is removable by interposing a pin to a bracket formed on the truck.