WO1995023894A1

WO1995023894A1 - Snow-clearing device

Info

Publication number: WO1995023894A1
Application number: PCT/SE1995/000231
Authority: WO
Inventors: Mats Svanström
Original assignee: Gradmeko Produktion Ab
Priority date: 1994-03-04
Filing date: 1995-03-06
Publication date: 1995-09-08
Also published as: AU1907495A; SE502565C2; SE9400740D0; SE9400740L

Abstract

The present invention relates to a snow-clearing device of the type which is adapted to be supported by a vehicle and which comprises a mould board (1) whose lower edge has at least one blade (11), which serves to abut, by a lower cutting edge, against the ground and to ensure a snow-cutting and snow-raising action and which is hingedly mounted in relation to the mould board and pivotable away against the action of a spring, thereby avoiding damage when running into an obstacle. The blade (11) is hingedly attached to a front end of at least one pivot member (9) which is directed forwards in relation to the mould board (1) and is pivotable downwards-backwards in relation to the pivot member from an upper stop position against the action of at least one first spring element (13), the pivot member being connected, in an area spaced from said front end, with a lower portion of the device and being pivotable upwards in relation thereto from a lower stop position against the action of at least one second spring element (14).

Description

SNOW-CLEARING DEVICE

The present invention relates to a snow-clearing device of the type adapted to be supported by a vehicle and comprising a mould board which at its lower edge has at least one blade whose lower cutting edge serves to abut against the ground and ensure a snow-cutting and snow-raising action, said blade being hingedly mounted relative to the mould board and pivotable away against the action of a spring, so as not to be damaged when run¬ ning into a possible obstacle, and again being pivotable forwards to be located in a position for snow-clearing after passing of the obstacle, said blade being hingedly attached, via a first pivot pin, to a front portion of at least one pivot member, which is forwardly directed rela¬ tive to the mould board, and being pivotable downwards- backwards relative to said pivot member from a front stop position, said pivot member being, in an area spaced from said front portion, hingedly connected via a second pivot pin to a lower portion of the device and being pivotable upwards relative to the device from a lower stop position against the action of at least one second spring element. Background of the Invention

For reasons of road safety and for economic reasons, great demands are made on both the result and the perfor¬ mance in snow-clearing of roads. Thus it is desirable that the device can remove substantially all loose snow lying on a roadway, i.e. as far as possible also snow lying in cavities in the form of e.g. ruts in the road¬ way, thereby making the road surface as safe as possible. This implies that the lower scraping or cutting edge of the device must operate in as close engagement with the roadway as possible. It is also desirable that the device can cut or scrap away any hard snow or ice adhering to the roadway and as far as possible remove this or at least level the road surface. Moreover, it should be pos- sible to carry out the above-mentioned snow-clearing work at high speed to enable clearing of long distances in a short time. Of course, this subjects the device and the vehicle to heavy stress, and they can be damaged if the cutting edge gets caught on an obstacle, for instance the edge of a gully cover or a pavement, while driving the vehicle.

To protect the vehicle and the device against such damage, it is previously known to mount the blade to be pivotable backwards, against the action of a spring, around a hinge positioned behind the blade at a distance from the roadway. The spring action is provided by means of compression springs which are positioned substantially vertically behind the mould board and secured to a sup¬ porting beam extended on the back of the mould board. A disadvantage of such snow-clearing devices is that the blade must be oriented substantially vertically to be smoothly pivotable away, i.e. at least approximately perpendicular to the roadway, thereby causing the lower edge of the blade, when pivoted away, to move substan- tially merely backwards-upwards and not to have any lift¬ ing effect on the device. It is thus not possible to position the blade in an evidently positive cutting angle relative to the vertical plane, with the lower cutting edge of the blade extended forwards in the direction of motion. As a result, the blade will operate with a scrap¬ ing effect against the roadway, rather than with a cut¬ ting effect, thereby making it necessary to press the device relatively firmly against the roadway to ensure good snow-clearing results. This implies that the ad- vancing of the device will be very heavy and power-con¬ suming. Further, it is not possible to carry out, by means of such a device, snow-clearing of transversely restricted cavities in the roadway even if the device, as is normally the case, is fitted with a plurality of short blades. Such snow-clearing devices will be relatively heavy, since they must be provided with a thick longitu¬ dinal beam for attachment of the compression springs. Snow-clearing devices are also known, in which the blade extends forwards in the direction of motion and has a positive cutting angle to the roadway. An example of such a plough construction, which corresponds to the preamble of claim 1 in the present application, is dis¬ closed in SE 9101176-7. In the plough according to this patent specification, each blade is connected to the mould board via at least two pivot arms, more specifical¬ ly via a lower pivot arm which is directed forwards in the direction of motion from the device to the blade and an upper pivot arm which is directed backwards against the direction of motion from the device to the blade. This means that each blade is rotatably or pivotally arranged around four different pivot pins and thus is movable along a fixed, controlled path of motion against the action of a spring striving to move the blade towards a lower end position. The path of motion of the blade is determined by the geometry of the construction, particu¬ larly the mutual positioning of the pivot pins. In the shown embodiment, the path of motion of the blade is such that the tip of the blade, when pivoted away, follows a wave-shaped path which first extends forwards-upwards, then deflects backwards-slightly downwards and, finally, backwards-upwards. This implies that when running into an obstacle, i.e. when forces directed horizontally against the direction of motion act on the blade, the tip of the blade must first be moved a distance forwards in the direction of motion before it can pivot backwards. In other words, the hinge connection of the blade has a dead centre position which is to be passed before the blade is pivoted away. It goes without saying that this can imply that the pivoting away of the blade is rendered quite impossible in some cases, for instance when striking an obstacle in the form of a sharp edge such as a gully cover or the edge of a pavement. In such cases, the blade will be prevented from initially moving upwards and at the same forwards, and there is thus a great risk of damaging the mould board and/or the vehicle. The imme¬ diate reason why the tip of the blade initially moves forwards is that the pivot arms in the normal position are oriented with an angle relative to each other which opens in the direction of motion. The dead centre posi¬ tion of horizontally directed forces is achieved when, owing to the raising of the blade, the pivot arms are oriented in parallel with each other, or just before this position. The reason for designing the plough in this fashion is that the blade is guided along a fixed path of motion in which pivoting and raising cannot take place independently of each other, but are connected with each other in a coacting motion. There would be a great risk that the result of the snow-clearing would be deficient if this dead centre position did not exist since, in that case, the blade would repeatedly be raised from the ground as soon as the forces originating from the snow- clearing resistance and acting on the blade counteract the downwardly directed force exerted by the spring ele- ment.

Summary of the Invention

The object of the present invention is to eliminate the above-mentioned problems and drawbacks of prior art and to provide a relatively simple, inexpensive and light snow-clearing device which, besides protecting the device and the vehicle from damage when running into an obstacle, permits mounting of the blade in a positive cutting angle relative to the roadway. At least these objects are achieved by a snow-clearing device according to claim 1.

The invention thus is based on the knowledge that this can be provided by arranging the blade both pivot¬ able around a first front pivot pin on a pivot arm or pivot member and displaceable upwards and downwards from and towards a lower end position by the pivot arm being connected to the device via a second rear pivot pin and the pivoting and displacing motion occurring indepen- dently of each other against the action of preferably separate spring elements. Each blade can be connected to the device via two or more pivot members. However, in such cases, it is necessary for all pivot pins between the blade and the pivot members and between the device and the pivot members to be positioned substantially aligned or coaxially with each other. By thus connecting the blade with the device, the advantage is obtained that the blade always abuts against the roadway and is capable of providing good snow-clearing results even if the tip of the blade is temporarily pivoted backwards, owing to high snow-clearing resistance, since the spring element acting downwards on the pivot element presses the blade against the roadway. A further object of the invention is to enable care¬ ful snow-clearing also of roadways having cavities in the form of e.g. ruts. At least this object is achieved by a snow-clearing device according to claim 2. Brief Description of the Drawing In the drawing:

FIG. 1 is a side view of the lower part of a snow-clear¬ ing device according to the present invention, the blade being in a forwardly directed snow- clearing position, FIGS 2 and 3 are side views according to Fig. 1, the blade being pivoted away in different positions, and FIG. 4 is a top plan view of a portion of the front part of a snow-clearing device in which the mould board is partly broken away.

Detailed Description of a Preferred Embodiment of the Invention

Reference is first made to Figs 1 and 4 which are a side view and a partly cut top plan view of the front lower part of a snow-clearing device according to the invention. In the Figures, a mould board 1 is indicated, being conventionally arched in cross-section. The lower edge of the mould board is connected with a beam 2 whose cross-section is unsymmetrically U-shaped, an upper portion 3 of the beam being connected with the lower edge of the mould board and extending backwards therefrom, a vertical portion 4 extending downwards from the upper portion, while a lower portion 5 extends forwards from the vertical portion at a distance from the ground.

The beam is, in suitable positions throughout its length, provided with transverse attachment plates 6 which serve as attachments for forwardly extending pivot arms 7. Each pivot arm is designed as an elongate body of flat rolled steel and, as shown in Fig. 4, the pivot arms are connected in pairs by means of flats 8, 8' to form a pivot element generally designated 9, which at its rear end is hingedly connected to two attachment plates 6 via a rear pivot pin in the form of a through bolt 10 and supports, at its front end, a blade 11 via a front pivot pin in the form of a through bolt 12. A front torsion spring 13 and a rear torsion spring 14, respectively, are arranged around the front and the rear bolt 12 and 10, respectively. The torsion springs are helical and arrang¬ ed such that the front torsion spring 13 strives to pivot the blade 11 forwards-upwards towards the end position shown in Fig. 1, in which the blade extends forwards in the direction of motion, while the rear torsion spring 14 strives to move the pivot element 9 downwards towards the end position shown in Fig. 1, in which the pivot member extends substantially horizontally, i.e. in a position in which the bolts 10, 12 are located in the same horizontal plane.

The space of motion between the blade 11 and the front part of the pivot arms 7, respectively, and the lower edge of the mould board 1 is covered by a flexible element 15 which suitably may consist of a thick cloth of rubber or plastic. More specifically, the lower part of the cloth 15 is clamped between the blade 11 and a posteriorly situated attachment plate 16, while the upper part of the cloth is attached to the lower side of the upper portion 3 of the beam 2. The cloth 15 ensures close connection between the blade 11 and the lower edge of the mould board, while permitting a pivoting motion of both the blade 11 and the pivot member 9. As a result, snow and ice will be raised from the ground by the blade and be passed up to the mould board and further to the sides, with no possibility of flowing down in the space of motion between the blade and the lower edge of the mould board.

The upper forwardly extended end or stop position of the blade as shown in Fig. 1 is occupied when the attach¬ ment plate 16 abuts against a front terminal edge 17 of the pivot arms, while its maximally backwardly pivoted end position is occupied when the attachment plate abuts against a lower edge 18 of the pivot arms. The cutting angle of the blade to the ground surface thus is deter¬ mined by the angle of the terminal edge 17 to the ground surface. Correspondingly, the maximally downwardly pivot- ed end or stop position of the pivot arms according to Fig. 1 is occupied, when the lower edge 18 of the pivot arms abuts against the upper surface of the lower portion 5 of the beam 2, while their maximally upwardly pivoted end position is occupied when an upper edge 19 of a stop lug of the pivot arms abuts against the lower part of the mould board or, as in the embodiment shown, against that portion of the cloth 15 which is attached to the lower part of the mould board and the upper portion 3 of the beam. This results in advantageous damping of the sound that may arise when the pivot arm is forcefully pivoted to its upper end position.

Figs 1-3 illustrate the pivoting-away motion of the blade 11 and the pivot arm 7, when striking an obstacle. If the blade 11 in the normal snow-clearing position of the device according to Fig. 1 strikes an obstacle, the lower edge of the blade will be stopped and while the device continues to advance, the front end of the pivot arm 7 is forced to move upwards, while the blade 11 is pivoted downwards-backwards in relation to the pivot arm to the position shown in Fig. 2, the blade being substan¬ tially vertically oriented. Continued pivoting of the blade upwards/backwards to the position in Fig. 3 permits the obstacle to pass under the device, without causing any damage or raising of the device. After the obstacle being passed, the torsion springs 13, 14 effect pivoting back of the blade 11 and the pivot arm 7 to the snow- clearing position shown in Fig. 1.

According to the present invention, a number of advantages are obtained over prior-art snow-clearing devices. Thus, the blade 11 can be mounted in a positive cutting angle in relation to the ground surface, which is favourable for snow-clearing. This improves the snow-cut¬ ting and snow-raising effect of the device and reduces the power that is required for advancing the device. By arranging, as illustrated in Fig. 4, a plurality of sepa¬ rate blades 11 throughout the length of the mould board, it is possible to obtain improved snow-clearing results for roadways having ruts or cavities. This can be achiev¬ ed by pressing the device downwards against the roadway by means of the lifting arms of the vehicle. The blade(s) 11 which is/are not positioned over a cavity will be pressed upwards from the position shown in Fig. 1 by pivoting of the pivot arm upwards around the bolt 10, while the blade(s) which is/are positioned over a cavity is pressed down into it. An individual blade 11 may suitably have a length of about 600 mm and a width of 200-300 mm. The angle of the blade to the ground in the normal snow-clearing position according to Fig. 1 is, in the preferred embodiment as illustrated, about 45°, but can be in the range of 20-70°, preferably 30-60°. Possible Modifications of the Invention Of course, the invention can be modified in various ways within the scope of the appended claims and in rela¬ tion to the preferred embodiment as described above. Thus, the pivot member 9 can be designed in many other ways than as pivot arms connected in pairs, for instance by a plate whose rear edge is pivotally connected to the device and whose front edge is pivotally connected to the blade. The pivot member should also be directed forwards from the device, but need of course not be oriented in parallel with the ground surface as in the embodiment shown. The attachment of the pivot member to the device can also be accomplished in other ways than via a U-shap- ed beam. Also the end or stop positions of the blade and the pivot member can be designed in optional manners, and the spring elements need, of course, not be precisely helical torsion springs. For instance, it would be pos¬ sible to use, instead of the rear torsion spring 14, a tension spring or compression spring extending between the pivot arm and the mould board or a supporting beam arranged thereon. It would also be possible to use tor¬ sion bars whose spring action arises by torsion of some suitable material. Instead of the flexible element 15, it would be possible to cover the space of motion between the blade and the lower part of the mould board by means of a rigid plate which is supported by the front end of the pivot member and abuts against the lower front sur¬ face of the mould board under spring loading.

Claims

1. A snow-clearing device of the type which is adapted to be supported by a vehicle and which comprises a mould board ( 1 ) which at its lower edge has at least one blade (11), which serves to abut against the ground by a lower cutting edge and to ensure a snow-cutting and snow-raising action and which is hingedly mounted rela- tive to the mould board and is pivotable away against the action of a spring, thereby avoiding damage when run¬ ning into a possible obstacle, and which is again pivot¬ able forwards to be located in a position for snow-clear¬ ing after passing of the obstacle, said blade (11) being hingedly attached, via a first pivot pin (12), to a front portion of at least one pivot member (9 ) directed for¬ wards in relation to said mould board ( 1 ) , and being pivotable downwards-backwards in relation to said pivot member from a front stop position, and said pivot member being hingedly connected, in an area spaced from said front portion, via a second pivot pin (10) to a lower portion of the device, and pivotable upwards in relation to said device from a lower stop position against the action of at least one second spring element (4) , c h a r a c t e r i s e d in that said blade (11) is connected to said device via pivot members (9) only, whose first and second pivot pins (10, 12) on said tool and said blade, respectively, are arranged coaxially or aligned with each other, and that at least one first spring element (13) acts on said blade to move it towards the front stop position, whereby said blade (11) is pivotable around said first pivot pin (12) on the front portion of said pivot member, and the pivot member (9) is pivotable around the second pivot pin ( 10) independently of each other against the action of spring elements.

2. The device as claimed in claim 1, c h a r a c ¬ t e r i s e d in that it is provided with a plurality of blades (11), each of which is considerably shorter than the length of said mould board ( 1 ) .

3. The device as claimed in claim 1 or 2, c h a r ¬ a c t e r i s e d in that said pivot member (9 ) consists of at least one pivot arm (7) .

4. The device as claimed in claim 3, c h a r a c ¬ t e r i s e d in that said pivot member (9 ) consists of two pivot arms (7) connected with each other and the hinges consist of two pins (10, 12) extending in parallel with said mould board ( 1 ) .

5. The device as claimed in any one of the preceding claims, c h a r a c t e r i s e d in that said spring elements (13, 14) consist of torsion springs.

6. The device as claimed in any one of the preceding claims, c h a r a c t e r i s e d in that a space of motion between said blade (11) and the lower edge of said mould board (1) is covered by a flexible element (15).

7. The device as claimed in any one of the preceding claims, c h a r a c t e r i s e d in that the pivot pins (10, 12) are, in the normal snow-clearing position, posi¬ tioned in a common plane essentially parallel with the ground surface.