JP3652519B2 - Cargo loading platform lifting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a load receiving base lifting device for a cargo handling vehicle, in particular, a load receiving base supported so as to be movable up and down on a vehicle body, a hydraulic cylinder disposed between the load receiving base and the vehicle body and capable of driving the load receiving base upward, and a hydraulic pressure thereof. The present invention relates to a load receiving table lifting device including a hydraulic pressure supply source for supplying hydraulic oil to a cylinder.
[0002]
[Prior art]
The cargo receiving platform lifting device for the cargo handling vehicle is conventionally known as described in, for example, Japanese Utility Model Publication Nos. 50-43856 and 51-44487.
[0003]
[Problems to be solved by the invention]
In the conventional load receiving platform lifting device, when the rising load receiving platform reaches the upper limit position, it suddenly decelerates and stops, so that it is easy to generate vibration and noise due to the impact at the time of stopping, and on the load receiving platform. There were problems such as the possibility that the loaded luggage might move.
[0004]
In order to solve such a problem, for example, the flow of hydraulic oil from the hydraulic supply source to the hydraulic cylinder in the ascending process of the load receiving table is performed after the load receiving table reaches the upper limit position. It is conceivable to stop the load receiving base in a buffered manner by gradually reducing the pressure by the device. In this case, the rate of change in the throttle flow rate of the hydraulic oil with respect to the operating stroke of the brake valve device (that is, upward displacement of the load receiving base) is kept constant Setting it has the following inconveniences. For example, when the constant change rate is set to be relatively large (that is, the flow of the hydraulic oil is rapidly reduced), the brake valve device cannot exhibit a sufficient buffering effect, so the load receiving platform is limited to the upper limit. When the position is reached, the impact will be relatively large, while if the rate of change is set to be relatively small (that is, the flow of hydraulic fluid will be throttled slowly), a sufficient buffering effect will be obtained. It is necessary to use a brake valve device with a long operating stroke, which increases the size of the brake valve device. In addition, it is necessary to decelerate the ascending speed early in the ascending process of the cargo cradle, and the time required for ascent increases accordingly. End up.
[0005]
This invention is made | formed in view of such a situation, Comprising: It aims at providing the load receiving stand raising / lowering apparatus of a cargo handling vehicle which can solve the said problem.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a first aspect of the present invention includes a load receiving base supported by a vehicle body so as to be movable up and down, a hydraulic cylinder disposed between the load receiving base and the vehicle body and capable of driving the load receiving base upward, a hydraulic supply source for supplying hydraulic fluid to the hydraulic cylinder, between the front SL hydraulic supply source and the hydraulic cylinder, consignee flow of hydraulic fluid in the receiving platform of the ascent process directed to the hydraulic cylinder from the hydraulic supply source In the load receiving platform lifting apparatus for a cargo handling vehicle, in which a brake valve device for bufferingly stopping the lifting operation of the load receiving table by buffering after the table reaches the vicinity of the upper limit position is interposed , the brake valve device includes: The cylinder hole so as to form an input / output port connected to the hydraulic supply source and the hydraulic cylinder, a valve box having a cylinder hole opened by both ports, and a communication path between the two ports. In And a sliding valve that can slide between a predetermined forward position and a backward position, and a valve spring that constantly urges the sliding valve toward the forward position side, The tapered portion is formed so as to gradually decrease in diameter toward the rear of the valve and gradually narrows the communication path in the retreating process from the advance position to the retreat position of the valve. The rear end of the part is provided so as to pass through the rear end of the opening of one of the ports, and the load receiving base rises from the vicinity of the upper limit position to the upper limit position between the sliding valve and the load receiving base. An interlocking mechanism for retracting the slide valve from the forward movement position to the backward movement position is provided .
[0007]
According to a second aspect of the present invention, there is provided a load receiving base that is supported by the vehicle body so as to be movable up and down, a hydraulic cylinder that is disposed between the load receiving base and the vehicle body and can drive the load receiving base upward, and hydraulic oil is supplied to the hydraulic cylinder. A hydraulic supply source that supplies hydraulic fluid flowing between the hydraulic supply source and the hydraulic cylinder in the vicinity of the upper limit position. In the load receiving platform lifting / lowering device for a cargo handling vehicle, in which a brake valve device for bufferingly stopping the lifting operation of the load receiving platform is provided by gradually squeezing after reaching, the brake valve device is connected to the hydraulic supply source and the hydraulic cylinder. Each of the input and output ports connected to each other, and a valve box having a cylinder hole in which both of the ports are opened, and a predetermined passage that is fitted into the cylinder hole so as to form a communication path between the two ports. Forward A sliding valve that can slide between the mounting position and the retreating position, and a valve spring that constantly urges the sliding valve toward the advancement position. An annular step portion that passes through the opening of one port in the process of retreating from the position to a predetermined intermediate retreat position and rapidly throttles the communication path, and is formed continuously to the front side of the annular step portion. A taper part is provided for slowly narrowing the communication path in the process of further retreating from the retracted position, and it is linked between the sliding valve and the load receiving table as the load receiving table rises from the vicinity of the upper limit position to the upper limit position. And an interlocking mechanism for retracting the sliding valve from the forward position to the backward position. Further, the invention of claim 3 is characterized in that, in addition to the above feature of the invention of claim 2 , the outer peripheral portion of the sliding valve. An annular recess that forms the communication path with the cylinder hole is provided behind the annular step. It is characterized by being continuously formed.
[0008]
In the present invention, the side on which the sliding valve moves in conjunction with the rising of the load receiving table is the rear side of the sliding valve, and the opposite side is the front side of the valve.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below based on the embodiments of the present invention illustrated in the accompanying drawings.
[0010]
In the accompanying drawings, FIG. 1 is a longitudinal side view of a rear part of a vehicle showing an embodiment of the present invention, FIG. 2 is a hydraulic control circuit diagram of the embodiment, FIG. 3 is an enlarged view of a portion indicated by an arrow 3 in FIG. Is a side view as seen from the direction of arrow 4 in FIG. 3, FIG. 5 is an overall longitudinal sectional view of the brake valve device in a state where the sliding valve is in the forward position, and FIG. 7 is a graph showing the relationship between the operating stroke of the brake valve device and the throttle flow rate, FIG. 8 is a diagram corresponding to FIG. 6 showing a modification of the brake valve device, and FIG. 9 is a cross-sectional view taken along line 9-9 of FIG. .
[0011]
First, in FIG. 1, a pair of left and right brackets 2 are fixed to the left and right ends of the rear part of the vehicle body 1 in the cargo handling vehicle T, and the bracket 2 and the load receiving table 3 are connected via a pair of left and right parallel link mechanisms 4. The parallel link mechanism 4 includes a tip portion of a piston rod 6 of a pair of left and right hydraulic cylinders 5 that rotatably supports a base portion at an appropriate position of the vehicle body 1 (for example, the bracket 2 or another bracket). It is connected and supported so as to be rotatable. Thereby, each parallel link mechanism 4 operates according to the expansion / contraction operation of each hydraulic cylinder 5, and the load receiving base 3 can be rotated up and down.
[0012]
Each parallel link mechanism 4 includes a pair of upper and lower swing links 7 and 8 parallel to each other, and a horizontal support shaft 9 for rotatably supporting the base ends of the swing links 7 and 8 on the bracket 2. , 10, an upright column 11 extending in the vertical direction, and horizontal pins 12 and 13 for rotatably connecting the ends of the swing links 7 and 8 to the upright column 11. The base ends of the swing links 7 and 8 are fixed to the support shafts 9 and 10, and the support shafts 9 and 10 are rotatably supported by the bracket 2. Moreover, an arm 14 is integrally provided on one of the support shafts 9 in the radially outward direction, and the tip of the piston rod 6 of the hydraulic cylinder 5 is rotatable at the tip of the arm 14. Connected to
[0013]
At the lower end of the upright support 11, the base end of the load receiving platform 3 is rotatably supported via a shaft 15 parallel to the pins 12 and 13. Moreover, the upper part of the upright support 11 and the tip of the load receiving table 3 are connected via a support link 16 that can be bent, and the load receiving table 3 is in a horizontal posture when the support link 16 is in the extended state. In addition, although not shown in figure, the drive means for forcibly rotating the load receiving table between the horizontal posture and the vertical posture and the holding means for holding the load receiving table in the vertical posture are necessary between the upright support column 11 and the load receiving table 3. Installed accordingly.
[0014]
Thus, when the hydraulic cylinder 5 is contracted while the support link 16 is extended to hold the load receiving table 3 in a horizontal posture, the load receiving table 3 is lowered as shown by the chain line in FIG. When the hydraulic cylinder 5 is extended on the contrary, by the action of the parallel link mechanism 4, the load receiving platform 3 is placed on the same plane as the loading platform 17 of the vehicle body 1 as shown by the solid line in FIG. It rises to the upper limit position 3U that contacts the rear edge.
[0015]
In FIG. 2, a hydraulic pump 19 as a hydraulic supply source that pumps hydraulic oil from the oil tank 18 is connected to a discharge oil passage 21, and a pair of connection oil passages 21 ₁ , 21 is provided downstream of the discharge oil passage 21. ₂ are connected in parallel, and hydraulic oil chambers 5a of a pair of left and right hydraulic cylinders 5 each composed of a single-acting cylinder are connected to both connecting oil passages 21 ₁ and 21 ₂ , respectively. In the middle of the discharge oil passage 21, a check valve 20 that allows the flow of hydraulic oil from the hydraulic pump 19 to the hydraulic cylinder 5 side and the brake valve device V of the present invention are connected in series from the upstream side in this order. Be dressed.
[0016]
A release oil passage 23 for returning the hydraulic oil in each hydraulic chamber 5a to the oil tank 18 is branched from the discharge oil passage 21 between the check valve 20 and the brake valve device V. A release valve 26 capable of opening and closing the passage 23 is interposed in the middle of the oil passage 23. The release valve 26 normally shuts off the release oil passage 23 by the check valve 22, and can be opened at any time according to an input operation to the operation member 25. It can be adjusted arbitrarily.
[0017]
Further, a relief oil passage 28 for returning the discharge oil of the pump 19 to the oil tank 18 is branched from the discharge oil passage 21 between the check valve 20 and the hydraulic pump 19. A known relief valve 24 that responds to the discharge pressure of the hydraulic pump 19 is connected in the middle of 28, and the discharge pressure of the hydraulic pump 19 can be limited to a predetermined pressure or less by the relief action.
[0018]
3 and 4 together, the brake valve device V is fixed to the support plate 27 fixed to the bracket 2 and is configured to operate according to the operating state of the parallel link mechanism 4.
[0019]
Next, a specific configuration of the brake valve device V will be described with reference to FIGS. The brake valve device V includes input and output ports 30 and 31 connected to the hydraulic pump 19 and the hydraulic chambers 5a of the left and right hydraulic cylinders 5, respectively, and a cylinder in which the input and output ports 30 and 31 are opened at intervals in the axial direction. A valve box 33 having a hole 32, and a sliding valve which is fitted in the cylinder hole 32 and can slide between a predetermined forward position A (solid line position in FIG. 5) and a reverse position C (FIG. 5 chain line position). And a valve spring 35 that constantly urges the valve 34 toward the forward position A. The valve spring 35 is fixed to the inner end of the blind hole 34b recessed in the rear end surface of the spool valve 34 and the outer surface of the valve box 33 with screws 36 so as to cover the open end of the blind hole 34b with a space. The spool plate 34 is held between the cover plate 42 and the cover plate 42 in an elastically compressed state, and the forward position of the spool valve 34 is determined by appropriate stopper means St (the valve 34 in the illustrated example) provided between the valve 34 and the valve casing 33. The rear end of the rear end portion of the valve box 33 and can be engaged with the rear end of the valve casing 33.
[0020]
A communication passage 40 is formed between the spool valve 34 and the cylinder hole 32 to always allow the input and output ports 30 and 31 to communicate with each other. In the illustrated example, output ports 31 are formed at the upper and side portions of the valve box 33 so as to distribute and supply the hydraulic oil from the brake valve device V to the pair of left and right hydraulic cylinders 5. Both the connecting oil passages 21 ₁ and 21 ₂ are connected to each other.
[0021]
The spool valve 34 has a pair of front and rear land portions 34Lf and 34Lr slidably fitted to the cylinder hole 32 via a seal ring S on the outer periphery, and between the land portions 34Lf and 34Lr. Is provided with an annular recess 34g that forms the communication passage 40 with the cylinder hole 32. Further, a conical taper-shaped taper portion 34t having a gradually decreasing diameter toward the rear is formed on the rear outer periphery of the front land portion 34Lf, and an annular step portion 34s is formed at the rear end portion of the taper portion 34t. The annular recess 34g continues on the rear side of the step 34s.
[0022]
In particular, the tapered portion 34t is in the middle of the retreating process of the spool valve 34 as shown in FIG. 6, that is, the opening portion of the port (the output port 31 in the illustrated example) whose rear end is the front end at the predetermined intermediate retracted position B. 31a so that it passes through the rear end (in other words, the rear end of the tapered portion 34t is located in front of the rear end of the opening 31a in the forward position A of the spool valve 34, and the reverse position C of the valve 34 Then, it is provided so that it may be located behind the rear end of the opening 31a. For this reason, until the rear end of the tapered portion 34t passes through the rear end of the opening portion 31a of the front port 31 during the backward movement of the spool valve 34 (that is, while the valve 34 reaches the intermediate backward position B from the forward movement position A). The taper portion 34t is gradually throttled in the sliding direction of the valve 34 at the portion of the communication passage 40 that directly faces the opening 31a, and after the passage (that is, the valve 34 is moved from the intermediate retracted position B to the retracted position C). Since the taper portion 34t can gradually narrow the rear portion of the communication passage 40 from the opening portion 31a in the radial direction of the valve 34, the taper portion 34t allows the communication passage 40 to be separated in two ways. It is possible to gradually squeeze in the aperture mode.
[0023]
6 and 7, in the process in which the spool valve 34 is retracted from the advance position A to the predetermined intermediate retract position B, the annular step 34s passes through the opening 31a of the front port 31. As a result, the communication passage 40 (particularly, the portion directly facing the opening 31a) can be rapidly throttled, and in the process in which the spool valve 34 is further retracted from the intermediate retracted position B, the tapered portion 34t is moved to the communication passage. 40 can be squeezed slowly. Further, the annular recess 34g that forms the communication passage 40 in cooperation with the cylinder hole 32 is formed continuously on the rear side of the annular step 34s, so that the hydraulic pressure from the hydraulic pump 19 affects the spool valve 34 itself. Since the forward and rearward thrust can be balanced (cancelled), the spool valve 34 can be smoothly slid accordingly.
[0024]
A bypass passage 41 is formed in the valve box 33 on one side of the spool valve 34 to bypass the communication passage 40 and short-circuit the output ports 30 and 31. This bypass passage 36 is provided with a ball valve type check valve 37 that allows only the flow of hydraulic oil from the output port 31 to the input port 30 (that is, return oil from the hydraulic cylinder 5 to the oil tank 18). The set valve opening pressure of the check valve 37 adjusts the set load of the valve spring 38 by appropriately rotating an adjusting screw 39 that is also used as a spring receiving means for supporting the return spring 38 of the valve 37. Can be arbitrarily adjusted. Thus, the check valve 37 is provided in the hydraulic cylinder 5 when there is heavy load on the load receiving table 3 in the descending process of the load receiving table 3 that is executed by arbitrarily opening the release valve 26. In order to prevent the return oil flow from the oil tank 18 to the oil tank 18 side from being throttled and slowed down by the spool valve 34 (taper portion 34t), the valve is opened in response to an increase in the differential pressure between the input and output ports 30 and 31. Thus, the descending operation of the load receiving platform 3 can be performed smoothly.
[0025]
Further, between the spool valve 34 and the load receiving platform 3, the spool valve 34 is moved back from the forward movement position A to the backward movement position C in conjunction with the rise of the load receiving rack 3 from the vicinity 3 U ′ of the upper limit position U to the upper limit position 3 U. An interlocking mechanism I is provided. This interlocking mechanism I is fixed to the outer end portion of the support shaft 9 in the parallel link mechanism 4 and extends outward from the support arm 52, and is screwed into the tip of the arm 52 so that the head portion of the spool valve 34. , And a pressing bolt 54 as a pressing member that can come into contact with the outer end 34 a extending to the outside of the valve casing 33, and a screwing position of the bolt 54 with respect to the support arm 52 can be fixed to the bolt 54. The lock nut 53 is screwed. Thus, the pressing bolt 54 abuts against the outer end 34a of the spool valve 34 and moves the valve 34 backward only when the load receiving platform 3 is at the upper limit position 3U shown in FIG.
[0026]
Next, the operation of the embodiment will be described. When the hydraulic cylinder 5 is contracted and the load receiving platform 3 is at the lower limit position as shown by a chain line in FIG. 1, the pressing bolt 54 is not in contact with the spool valve 34, so the spool valve 34 is moved forward by the valve spring 35. In this state, the passage cross-sectional area of the opening 31a of the output port 31 (therefore, the communication passage 40 between the ports 30 and 31) is maximum.
[0027]
Here, when the hydraulic pump 19 is operated to raise the load receiving platform 3, a large amount of the discharged oil is supplied to the hydraulic cylinder 5 side through the discharge oil passage 21, whereby the hydraulic cylinder 5 is quickly expanded and expanded. The load receiving platform 3 that is linked to the operation via the parallel link mechanism 4 is quickly moved up.
[0028]
When the load receiving platform 3 reaches the vicinity 3U 'near the upper limit position 3U, the pressing bolt 54 of the interlocking mechanism I comes into contact with the outer end of the spool valve 34, whereby the valve 34 starts to move backward. The spool valve 34 retreats in conjunction with the further elevation of the load receiving platform 3, and the communication passage 40 (therefore, the flow of hydraulic oil from the hydraulic pump 19 to the hydraulic cylinder 5 side) gradually moves along with the retraction operation. Since it is narrowed down, the ascending load receiving tray 3 can be bufferedly stopped at the upper limit position 3U. Therefore, since the occurrence of an impact at the time of stopping is suppressed, the generation of vibration and noise due to the impact can be effectively prevented, and the displacement movement of the load on the load receiving platform 3 can be effectively suppressed.
[0029]
In this case, the communication passage 40 (and thus the flow of the hydraulic oil toward the hydraulic cylinder 5) is a process in which the spool valve 3 is retracted from the advance position A to a predetermined intermediate retract position B (section A → B in FIG. 7). Then, the valve 34 is throttled rapidly mainly by the annular step 34s, and then in the process in which the valve 34 is further retracted from the intermediate retracted position B (section B → C in FIG. 7), the valve 34 is gradually slowed by the tapered portion 34t. Therefore, it is possible to shorten the operation stroke of the valve 34 as much as possible while exerting the buffering effect required for the brake valve device V and reducing the impact when the upper limit position 3U of the load receiving table 3 arrives. The size of the brake valve device V can be reduced. Moreover, it is not necessary to decelerate the rising speed until the receiving platform 3 reaches the vicinity 3U 'near the upper limit position 3U during the rising process of the receiving platform 3, so that the required time for raising is shortened as much as possible to improve the work efficiency. .
[0030]
8 and 9 show a modified example of the spool valve 34 as a sliding valve. That is, in the previous embodiment, when providing the tapered portion 34t to the spool valve 34, the outer periphery of the rear half of the land portion 34Lf on the front side of the valve 34 is formed from the conical tapered surface. The outer periphery of the rear half of the land portion 34Lf has a cylindrical shape, and a tapered groove 34t whose passage cross-sectional area (groove width / groove bottom) gradually increases toward the rear of the outer peripheral surface corresponds to the opening 31a of the front port 31. At least one strip (a plurality of strips in the illustrated example) is formed, and this is a tapered portion. Thus, this modification can also be expected to have the same effect as the above-described embodiment.
[0031]
As mentioned above, although the Example of this invention was described, this invention is not limited to the Example, A various Example is possible within the scope of the present invention. For example, in the above-described embodiment, an example is shown in which the present invention is applied to a cargo handling vehicle of a type in which the load receiving platform 3 is supported on the vehicle body 1 via the parallel link mechanism 4 so as to be capable of moving up and down. You may apply to the cargo handling vehicle of the type which supported the load receiving stand so that vertical raising / lowering was possible.
[0032]
In the above embodiment, the output port 31 is disposed in front of the input port 30 so that the annular step portion 34s and the taper portion 34t of the spool valve 34 sequentially pass through the opening 31a of the output port 31. In the present invention, the input port 30 is disposed in front of the output port 31 so that the annular step 34s and the tapered portion 34t of the spool valve 34 pass through the opening of the input port 30 sequentially. Good.
[0033]
Further, in the above-described embodiment, the annular step portion 34s is formed at the rear end of the tapered portion 34t provided on the outer periphery of the spool valve 34. In the present invention (claims 1 and 2), the rear portion of the tapered portion 34t is provided. The bottom of the annular recess 34g may be continuous without the stepped portion at the end, and the annular stepped portion may be omitted.
[0034]
【The invention's effect】
As described above, according to the present invention, between the hydraulic cylinder that can drive the load receiving table up and the hydraulic supply source that supplies hydraulic oil to the hydraulic cylinder, the hydraulic supply source supplies the hydraulic pressure in the ascending process of the load receiving table. A brake valve device is provided to stop the ascending operation of the load receiving buffer in a buffering manner by gradually reducing the flow of hydraulic oil toward the cylinder after the load receiving base reaches the vicinity of the upper limit position. The ascending load cradle can be buffered to the upper limit position, so that the shock during the stop can be mitigated, and vibration and noise caused by the shock can be effectively prevented, and the load cradle It is possible to suppress the shifting movement of the upper load.
[0035]
According aspect of the present invention in particular 1, while in the retracted course of sliding valve operating until the tapered rear end passes through the opening rear end of one port (i.e. the front tapered portion rear end than the opening rear end The taper is gradually throttled in the sliding direction of the valve in the direction of the valve, and after the passage (that is, the rear end of the taper moves backward from the rear end of the opening). After that, the taper part can gradually narrow the rear part of the communication path from the opening part in the radial direction of the valve. As a result, the taper part supplies hydraulic pressure in the process of raising the communication path (and hence the load receiving platform). The flow of hydraulic oil from the power source toward the hydraulic cylinder) can be effectively throttled in two ways of throttling, so that the shock is generated when the upper limit position of the load receiving platform is reached with the brake valve device exhibiting sufficient buffering effect. Can be effectively suppressed, and the buffer characteristics can be diversified. It is possible.
[0036]
In particular, according to the invention of claim 2 , the communication valve between the input and output ports (therefore, the flow of hydraulic oil from the hydraulic supply source toward the hydraulic cylinder in the ascending process of the load receiving platform) In the process of retreating to the intermediate retracted position, the valve can be rapidly throttled by the annular stepped portion of the valve, and then in the process of further retreating the slide valve from the intermediate retracted position, the valve can be gently throttled by the tapered portion. As a result, the stroke of the valve can be shortened as much as possible while exerting a sufficient buffering effect on the brake valve device to mitigate the impact when the upper limit position of the cargo cradle arrives. In addition, since it is not necessary to decelerate the rising speed until the load receiving table reaches the vicinity of the upper limit position in the process of ascending the load receiving table, it is possible to improve the working efficiency by shortening the time required for rising as much as possible.
[0037]
In particular, according to the invention of claim 3 , the annular recess that forms the communication path with the cylinder hole is formed continuously on the rear side of the annular step portion in the outer peripheral portion of the sliding valve. The axial thrust exerted by the hydraulic pressure on the sliding valve itself can be balanced back and forth, and the sliding valve can be slid smoothly.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional side view of a vehicle rear portion showing an embodiment of the present invention. FIG. 2 is a hydraulic control circuit diagram of the embodiment. FIG. 3 is an enlarged view of a portion indicated by an arrow 3 in FIG. 4 is a side view as seen from the direction of arrow 4 [FIG. 5] An overall longitudinal sectional view of the brake valve device in a state in which the sliding valve is in the forward position [FIG. 6] FIG. FIG. 8 is a graph showing the relationship between the operation stroke and the throttle flow rate. FIG. 8 is a diagram corresponding to FIG. 6 showing a modified example of the brake valve device.
DESCRIPTION OF SYMBOLS 1 ...... Car body 3 ... Cargo stand 3U ... Upper limit position 3U '... Near the upper limit position 5 ... Hydraulic cylinder 19 ... Hydraulic pump 30 as a hydraulic supply source ... Input Port 31 ... Output port (one port)
31a .. Opening 32... Cylinder hole 33... Valve box 34... Spool valve 34g as a sliding valve... Annular recess 34s. 40 ... Communication path A ... Forward position B ... Intermediate reverse position C ... Reverse position I ... Interlocking mechanism T ... Cargo handling vehicle V ... Brake valve device

Claims (3)

A load receiving base (3) supported by the vehicle body (1) so as to be movable up and down, and a hydraulic cylinder (5) disposed between the load receiving base (3) and the vehicle body (1) to drive the load receiving base (3) upward. ) And a hydraulic pressure supply source (19) for supplying hydraulic oil to the hydraulic cylinder (5) ,
Between the hydraulic pressure supply source (19) and the hydraulic cylinder (5), the flow of hydraulic fluid from the hydraulic pressure supply source (19) toward the hydraulic cylinder (5) in the ascending process of the load receiving platform (3). A brake valve device (V) for bufferingly stopping the ascending operation of the load receiving platform (3) is provided by gradually squeezing after (3) reaches the vicinity (3U ') of the upper limit position (3U) . In the loading platform lifting device of the cargo handling vehicle,
The brake valve device (V) includes an input / output port (30, 31) connected to a hydraulic supply source (19) and a hydraulic cylinder (5), and a cylinder hole (32) in which both ports (30, 31) are opened. ) And the cylinder hole (32) so as to form a communication path (40) between the valve box (33) having both the port (30, 31) and the cylinder hole (32). A sliding valve (34) that can slide between a predetermined forward position (A) and a backward position (C), and a valve spring that constantly biases the sliding valve (34) toward the forward position (A). (35)
An outer peripheral portion of the sliding valve (34) is formed so as to gradually become smaller in diameter toward the rear of the valve (34), and the valve (34) is moved from the forward position (A) to the backward position (C). The taper portion (34t) that gradually narrows the communication path (40) during the retreating process, and the rear end of the taper portion (34t) is the rear end of the opening (31a) of one port (31) during the retreating process. Is provided to pass through
Between the slide valve (34) and the load receiving table (3), the load receiving table (3) slides in conjunction with ascending from the vicinity (3U ') of the upper limit position (3U) to the upper limit position (3U). A load receiving platform elevating device for a cargo handling vehicle, wherein an interlocking mechanism (I) for moving the valve (34) from a forward position (A) to a reverse position (C) is provided . A load receiving base (3) supported by the vehicle body (1) so as to be movable up and down, and a hydraulic cylinder (5) disposed between the load receiving base (3) and the vehicle body (1) to drive the load receiving base (3) upward. ) And a hydraulic pressure supply source (19) for supplying hydraulic oil to the hydraulic cylinder (5),
Between the hydraulic pressure supply source (19) and the hydraulic cylinder (5), the flow of hydraulic fluid from the hydraulic pressure supply source (19) toward the hydraulic cylinder (5) in the ascending process of the load receiving platform (3). A brake valve device (V) for bufferingly stopping the ascending operation of the load receiving platform (3) is provided by gradually squeezing after (3) reaches the vicinity (3U ') of the upper limit position (3U). In the loading platform lifting device of the cargo handling vehicle,
The brake valve device (V) includes an input / output port (30, 31) connected to a hydraulic supply source (19) and a hydraulic cylinder (5), and a cylinder hole (32) in which both ports (30, 31) are opened. ) And the cylinder hole (32) so as to form a communication path (40) between the valve box (33) having both the port (30, 31) and the cylinder hole (32). A sliding valve (34) that can slide between a predetermined forward position (A) and a backward position (C), and a valve spring that constantly biases the sliding valve (34) toward the forward position (A). (35)
An opening (31a) of one port (31) is provided on the outer peripheral portion of the sliding valve (34) in the process in which the valve (34) is retracted from the advance position (A) to a predetermined intermediate retract position (B). An annular step portion (34s) that rapidly squeezes the communication passage (40) through the valve and a front side of the annular step portion (34s), and the valve (34) is formed from the intermediate retracted position (B). In addition, a taper portion (34t) that gently throttles the communication path (40) in the process of retreating is provided,
Between the slide valve (34) and the load receiving table (3), the load receiving table (3) slides in conjunction with ascending from the vicinity (3U ') of the upper limit position (3U) to the upper limit position (3U). wherein the valve operating interlocking mechanism for retracting (34) the forward position (a) to a retracted position (C) (I) is provided, receiving platform lifting device of cargo handling vehicle. An annular recess (34g) that forms the communication passage (40) between the slide valve (34) and the cylinder hole (32) is connected to the rear side of the annular step portion (34s). The cargo receiving platform lifting / lowering device for a cargo handling vehicle according to claim 2 , wherein the cargo receiving platform lifting / lowering device is formed.

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