Abstract:
The invention relates to adjustable stop-wagon retarders with locking function for wagons at high speed and disposal methods thereof, which are suitable for railway marshaling yards or rail lines where it is required to prevent wagons from running away, which are hydraulic equipment of no external energy source to automatically regulate wagon&#39;s speed and disposal methods of such equipment. The stop-wagon retarder is characterized in that a uni-directional return unit comprising a sealing valve plate and adjustable throttle valve, and a locking control valve composing of switch valve and positioning unit are mounted in the piston assembly, which make the returning speed and the locking speed for wagon at high speed adjustable, thus the aim of setting the retarder with different control levels and thresholds according to the wagon speed is realized. The disposal method is characterized in that the distances between every two adjacent stop-wagon retarders correspond to the distances between every two adjacent wheel axles.

Description:
FIELD OF INVENTION 
     The invention relates to adjustable stop-wagon retarders with locking function for wagons at high speed and disposal methods thereof, which are suitable for railway marshaling yards or rail lines where it is required to prevent wagons from running away, and more particularly, to adjustable stop-wagon retarders which are hydraulic equipment of no external energy source, mounted on the track to automatically regulate wagon&#39;s speed and disposal methods of such equipment. 
     BACKGROUND OF INVENTION 
     A multifunctional stop-wagon retarder for railway wagon is disclosed in Chinese Pat. No. ZL92232912.5. This retarder can reduce the speed of a wagon, stop a wagon, or prevent a stalled wagon from running away. And it will do work on a wagon at low speed, and be locked by a wagon at high speed. However, the retarder has disadvantages. The structure of its uni-directional return unit makes the normal returning speed of sliding cylinder unadjustable and therefore, the retarder can not have different control levels. The term “control level” means the time necessary for the sliding cylinder of the stop-wagon retarder to return to its original position after it is deflected downwards by a wheel of the wagon. It&#39;s locking control valve can not regulate the locking speed and different thresholds for controlling the locking speed can not be set. The connection mode of the positioning unit is complicated and its components are liable to come off, which affects locking precision. And the exhaust hole located rather low in the housing harms its water prevention performance. In addition, existing disposal method for stop-wagon retarders adopts centralized method to dispose large retarder group which can not achieve good retardation on wagons. 
     SUMMARY OF INVENTION 
     Accordingly, the first object of the present invention is to provide an adjustable stop-wagon retarder with locking function for a wagon at high speed, which can overcome the above shortcomings of the prior art and can adjust the returning speed and the locking speed of the stop-wagon retarder and therefore, can realize different control levels and thresholds, achieve reliable control and be effective in protecting from water harm. 
     The second object of the present invention is to provide an optimized disposal method of stop-wagon retarders. 
     According to the first aspect of the invention, there is provided an adjustable stop-wagon retarder with locking function for a wagon at high speed including a sliding cylinder assembly and a housing assembly having an exhaust unit, the sliding cylinder assembly comprising a cylinder; a piston slidably housed in said cylinder and dividing the cylinder into an upper chamber and a lower chamber; a pressure valve and a locking control valve both disposed coaxially with said piston; an unlocking unit; at least one uni-directional return unit installed on the piston and a sealing gland mounted on the lower end of the cylinder; said sliding cylinder assembly being charged with hydraulic oil and nitrogen and can longitudinally reciprocate between an upper position and a lower position, a portion of said sliding cylinder being disposed in the path of a wheel of said wagon, and said portion when engaged, directly or indirectly, by a wheel being deflected by, and out of the path of, said wheel to permit the wheel to pass the retarder, said uni-directional unit comprises a sealing valve plate and at least one adjustable throttle valve, the sealing valve plate and a pressure valve seat being mounted coaxially on the upper part of the piston with an adjustable gap between the valve plate and the valve seat, and the adjustable throttle valve being disposed under the valve plate for controlling the speed of the hydraulic oil returning to the upper chamber from the lower chamber of the cylinder; said locking control valve comprises a switch valve and at least one positioning unit, said control valve being disposed around the position between the head of the piston and the sealing gland and rotable between an unlock position in which at least one flowing orifice on the switch valve is aligned with the adjustable throttle valve and a lock position in which the flowing orifice is displaced from the adjustable throttle valve, said unlock position and said lock position being limited by at least one positioning unit; the switch valve comprising at least one locking oblique, an unlocking oblique, the flowing orifice and a leaking orifice, the locking oblique being impacted by the hydraulic oil from a piston outlet so that the switch valve rotates in one direction towards the lock position when the wagon travels at a speed higher than a predetermined value; the leaking orifice being aligned with the adjustable valve in the lock position so that the hydraulic oil can slowly return to the upper chamber from the lower chamber, and therefore, the cylinder can slowly return to its upper position; and the unlocking oblique cooperating with said unlocking unit so that the switch valve rotates in a direction opposite said one direction towards the unlock position. 
     Preferably, the outlet of said exhaust unit is disposed at a high position so as to prevent water from entering the retarder. 
     In the adjustable stop-wagon retarder with locking function for a wagon at high speed, the adjustable throttle valve can comprise a step-shaped throttle orifice having coaxially a larger diameter upper section and a smaller diameter lower section, and therefore a shoulder being formed therebetween. 
     The adjustable throttle valve can further comprise a steel ball disposed on the shoulder in the step-shaped orifice. 
     A compression spring can be disposed in the throttle orifice between the steel ball and the sealing valve plate, biasing the steel ball towards the shoulder. 
     In the adjustable stop-wagon retarder with locking function for a wagon at high speed, the positioning unit can comprise a positioning lock disposed in the switch valve and two positioning recesses disposed in the piston. The positioning lock comprises a spring seat fixed in a radial orifice in the switch valve; a steel ball installed in the radial orifice and a compression spring disposed in the radial orifice between the steel ball and the bottom of the spring seat, biasing the steel ball so as to engage with one of the recesses in said unlock position and engage with the other of the recesses in said lock position. 
     In the uni-directional return unit of the stop-wagon retarder according to the present invention, the returning speed can be regulated and different control levels can be achieved by adjusting the gap between the valve plate and pressure valve seat or the diameter of the throttle orifice, or by increasing or decreasing the number of the adjustable throttle valves. 
     In the locking control valve of the stop-wagon retarder according to the present invention, the locking speed can be regulated by changing the locking force between the positioning lock and positioning recess, increasing or decreasing the number of the positioning units and therefore, different thresholds can be set as required. 
     According to the second aspect of the invention, there is provided a method for disposing stop-wagon retarders, especially the adjustable stop-wagon retarders with locking function for a wagon at high speed according to the present invention, characterized in that, in at least one section of the track along which stop-wagon retarders are disposed, the distances between every two adjacent stop-wagon retarders correspond to the distances between every two adjacent wheel axles. 
     It is preferable that two sections, in which the distances between every two adjacent stop-wagon retarders correspond to the distances between every two adjacent wheel axles, are arranged respectively as the entrance section and the exit section of said track along which stop-wagon retarders are disposed, and in the central section between the entrance section and the exit section, stop-wagons retarders are disposed intensively. 
     A small group of protective stop-wagon retarders can be disposed at a distance from said exit section along the track for preventing uncoupled wagons from running away when hit by the following wagons. 
     Preferably, the stop-wagon retarders disposed along said track are divided into a plurality of groups in the wagon running direction, the normal returning speed and the locking speed of the stop-wagon retarders in an upstream group are higher respectively than the normal returning speed and the locking speed of the stop-wagon retarders in a downstream group. 
     The stop-wagon retarders can be disposed on the same side of one rail of said track, or on the inner sides of both rails of said track, or on the outer sides of both rails of said track. 
     Compared with the existing technology, this invention has the following advantages: 
     1. The uni-directional returning unit is of adjustable structure, which can meet the need to set the control levels according to returning speed. The sealing valve plate and steel ball provide double sealing effect and therefore improve retardation; 
     2. The locking control valve can adjust its locking speed and be set to different thresholds, and its positioning unit is of simple and reliable structure. And locking speed is precisely controlled; 
     3. Exhaust outlet disposed at a higher position is more effective in keeping water, snow and foreign matter from entering the housing; 
     4. The method for disposing retarders according to the present invention provide a greater retardation than the intensive disposal method. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an elevational section of the general structure of the adjustable stop-wagon retarder with locking function for a wagon at high speed according to the present invention. 
     FIG. 2 shows, on an enlarged scale, part of FIG. 1 (including uni-directional returning unit, the locking control valve and unlocking unit). 
     FIG. 3 shows, on an enlarged scale, the block in FIG. 1 (including the positioning unit and the switch valve). 
     FIG. 4, FIG.  5  and FIG. 6 are partial sectional views respectively showing Embodiments 1, 2 and 3. 
     FIG. 7 is a plan view of the switch valve. 
     FIG.  8  and FIG. 9 are sectional views respectively along lines of C—C and A—A in FIG.  7 . 
     FIG. 10 is a layout showing an embodiment of the method for disposing the stop-wagon retarders according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiment 1 
     In Embodiment 1, a sealing valve plate  12  that form part of a uni-directional returning unit, and a pressure valve seat  13  that are mounted coaxially on the top of a piston  3 , leaving an adjustable gap h between the sealing valve plate  12  and the pressure valve seat  13 . An adjustable throttle valve is mounted under the valve plate  12 , forming a passage through the head of the piston  3  in the axial direction. The adjustable throttle valve comprise a step-shaped throttle orifice  9  having coaxially a larger diameter upper section and a smaller diameter lower section, and therefore a shoulder being formed therebetween; a steel ball  10  disposed on the shoulder in the step-shaped orifice  9 ; and a compression spring  11  disposed in the throttle orifice  9  between the steel ball  10  and the sealing valve plate  12 , biasing the steel ball  10  towards the shoulder (FIGS.  2  and  4 ). 
     Between the piston head  3  and the sealing gland  2 , a locking control valve is installed around the piston and can rotate around the axis. Its rotation angle is limited by a positioning unit. A switch valve  24  is of integral structure, including at least one locking oblique  16 , an unlocking oblique  17 , at least one flowing orifice  14  and a leaking orifice  15 . And the positioning unit comprises positioning locks  25 ,  26  and  27  located on the switch valve and positioning recesses  28  and  29  on the piston. When the locking control valve rotates around the axis clockwise or anti-clockwise, the flowing orifice  14  on the switch valve will accordingly open to or shut off from the throttle orifice  9  of the adjustable throttle valve, that is, in the unlock or lock positions (FIG. 2, FIG. 7 FIG.  8  and FIG.  9 ). Each set of positioning unit has one positioning lock and two positioning recesses. The positioning lock is formed by a positioning steel ball  25 , a positioning spring  26  and spring seat  27  which are mounted inside a radial positioning orifice  30  of the switch valve  24  in sequence. The spring seat  27  is fastened in the switch valve  24 . The shape and location of positioning recesses  28  and  29  that are arranged on the same cycle around the piston, match with the positioning steel ball  25 , and the pitch between the positioning recesses ensures that the flowing orifice  14  can fully open to or shut off from the throttle orifice  9  of the adjustable throttle valve, when the locking control valve rotates around the axis clockwise or anti-clockwise (FIG.  3  and FIG.  2 ). 
     The unlocking unit in this embodiment is of the basic structure in the existing technology, that is, it comprises a pusher  18 , pilot sleeve  19  and a binding screw  22 . In this invention, it further comprises a restoring spring  20  and a collar  21  to improve automatic restoring function of the unlocking unit (FIG.  3 ). An exhaust unit disposed in the upper part of the housing is comprises a sealing ring  4 , a high exhaust seat  5 , a positioning pin  6  and a high exhause pipe  7  (FIG.  1 ). 
     Embodiment 2 
     The structure of this embodiment is similar to that of Embodiment 1 except that the adjustable throttle valve only has a step-shaped throttle orifice  9  having coaxially a larger diameter upper section and a smaller diameter lower section, a steel ball  10  and a sealing valve plate  12  (FIG.  5 ). 
     Embodiment 3 
     The structure of this embodiment is similar to that of Embodiment 1 except that the adjustable throttle valve only has a step-shaped throttle orifice  9  having coaxially a larger diameter upper section and smaller diameter lower section and a sealing valve plate  12  (FIG.  6 ). 
     In this invention, the number of the adjustable throttle valves should be decided by the normal returning speed of the stop-wagon retarder, scaling up with the returning speed. And from the above Embodiments, it is known that increasing the adjustable gap h between the sealing valve plate  12  and the pressure valve seat  13 , reducing the force of spring  11 , and enlarging aperture of throttle orifice  9 , can all enhance the normal returning speed of the cylinder; and in opposite ways the returning speed can be lowered. By regulating the above factors in a comprehensive way, the normal returning speed can be changed as required and the control levels set according to the normal returning speed. 
     The number of the positioning units in the locking control valve should be dependent on the locking speed of the stop-wagon retarder, scaling up with the locking speed. And from the above Embodiments, it is known that increasing the force of the positioning spring  26  or the depth of the positioning recesses  28  and  29  can enhance the locking speed; and in opposite ways the locking speed can be lowered. By regulating the above factors in a comprehensive way, the locking speed can be changed as required and the thresholds set according to the speed. 
     The following is a brief introduction to the operation of the adjustable stop-wagon retarder with lock function for wagons at high speed: 
     1. Retardation status: In the static condition, fluid in the upper and lower chambers of the cylinder  8  has equal pressure, the flowing orifice  14  on the switch valve  24  is open to the throttle orifice  9  of the adjustable throttle valve, and the locking control valve is in the unlocking position. When a wagon hit the retarder at a comparatively low speed, the wheel will press the cylinder head and the cylinder moves downwards. Therefore, the fluid in the upper chamber can not enter the lower chamber due to isolation of the sealing valve plate  12  and the steel ball  10 . The cylinder will continue to move downwards and the upper chamber become smaller, till the compressed nitrogen forces the pressure valve open, that is, a retardation is exerted on the wheel. Then the fluid in the upper chamber will flow out through the pressure valve and a piston outlet  23 . As the wagon travels at low speed, the fluid flows slowly and can not move the switch valve. The fluid in the lower chamber can flow through the flowing orifice  14  and the throttle orifice  9  to push open the steel ball  10  and quickly back to the upper chamber to restore the cylinder rapidly. And the same process is repeated for the following wheels. 
     2. Locking status for wagon at high speed: When a wagon hits the retarder at a rather high speed, the first wheel will press the cylinder and the retarder exerts retardation on the wheel. As the wagon travels fast, fluid from piston outlet  23  will rush to the locking oblique  16  on the switch valve  24 . The impact is larger than the locking force between the positioning steel ball  25  and the positioning recess  28 , and the switch valve is forced to rotate anti-clockwise, and the flowing orifice  14 , the leaking orifice  15  and the positioning lock also move. Positioning steel ball  25  moves into the positioning recess  29 . At this time, since the oblique  16  moves away from the piston outlet  23  and the fluid can no more rush to the oblique, the switch valve will stop rotation under the locking force of the positioning steel ball and the positioning recess. The flowing orifice  14  is now shut off from the throttle orifice  9 , the leaking orifice  15  is open to the throttle orifice  9 , and the locking control valve is in the locking position. The aperture of the leaking orifice  15  is so small that fluid from the lower chamber could only flow very slowly to the upper chamber, which means the cylinder  8  will be locked at the position lower than the top of rail and the retarder will not exert retardation against the following wheels. 
     3. Automatic unlocking: When the track is clear, under the pressure of expansion of nitrogen, fluid in the lower chamber of the cylinder flows slowly back to the upper chamber via the leaking orifice  15 , the throttle orifice  9 , the steel ball  10  and the sealing valve plate  12 . The cylinder slowly moves upwards. And the sealing gland  2  moves up accordingly. When the gland  2  approaches the highest point, the top surface of the gland  2  will force the pusher  18  to move up. The upmost top of the pusher  18  will reach the unlocking oblique  17  on the switch valve  24  and force the switch valve  24  rotate clockwise. So the flowing orifice  14 , the leaking orifice  15  and the positioning lock on the valve change their positions accordingly, and the positioning steel ball  25  moves back into the positioning recess  28 . And under the action of restoring spring  20 , the pusher  18  is automatically restored. The locking force between the positioning steel ball and the positioning recess make the switch valve stop rotating. The flowing orifice  14  on the switch valve is open to the throttle orifice  9  now, and the locking control valve returns to unlocking position. Thus the stop-wagon retarder is automatically unlocked. 
     4. Holding status: When a wheel stops at the retarder, the cylinder can not move upwards under the pressure of the wheel. Nitrogen in the upper chamber is compressed, which makes the pressure in the upper chamber higher than that of the lower chamber. And the sealing plate and sealing ring prevent the fluid in the upper chamber from entering the lower chamber, that is, the cylinder exerts a certain retarding force against the wheel for rather a long time, so that the wagon is prevented from running away. 
     Embodiment 4 
     FIG. 10 shows arrangement of the adjustable stop-wagon retarders with locking function for wagons at high speed, along a railway track so as to prevent Chinese 4-axle wagons from running away. 
     The retarders are symmetrically disposed on the inner sides of both rails of the track. The distance a between each pair of retarders is 1.75 m, the distance b between every two pairs of retarders 2.97 m, and the distance c between every two adjacent groups of retarders 6.9 m. In the central section of the track section where the retarders are arranged, 18 pairs of retarders are intensively disposed. The central section extends a length l of 11 m. A plurality of protective retarders are set at a distance of 23 m to the end of said track section. The above arrangement is mainly based on the fact that for the 4-axle wagons of the Chinese Railways, the distance between axles in each bogie is 1.75 m, the distance between the inner axles of two adjacent bogies 6.9 m, and the distance between the last wheel of the previous wagon and the first wheel of the following wagon 2.97 m. The number of retarders is calculated on the gradient of the track profile, the weight and quantity of stalled wagons and the traveling resistance of wagons. The purpose of the 18 pairs of retarders intensively disposed in the central section is to enhance the total braking capacity of these retarders. And for the sake of transport safety, protective retardes are set to prevent uncoupled wagons from running away when hit by the following wagons. 
     The disposal method according to the present invention is also applicable to other types of stop-wagon retarders or anti-runaway equipment.