GUSTAFSSON, Leif (Snapphanevägen 6, Saluboda, Holmsjö, S-370 34, SE)
Patent claims
1. A hydraulic wing damper (1) designed for use on a two or four- wheeled vehicle, in which the wing damper (1) comprises an outer housing (2) consisting of an upper lid (2a) and a lower housing part (2b), which enclose a damping-medium-filled main chamber (3) divided by a demarcating wing (4) rotatable about a first wing end (4a) into two chambers (3a, 3b), each with its own working volume, and in which the outer face (4a) of the wing end (4a) rotates in a custom-made cutout (2c) in the lower housing part (2b), and in the first wing end (4a) there is fixed a first end of a lever (4b), so that the lever (4b), in relation to said outer housing (2), rotates with the wing (4) about a rotation axis (RA) substantially centered in the first lever end, in which connected to the main chamber (3) there is arranged a pressurized space (6) having a certain volume designed to be used to compensate for the change in volume of the damping medium due to a change in temperature of the medium, characterized in that the space (6) for pressure compensation is arranged directly connected to the cutout (2c) in the housing part (2b), in which cutout the outer face (4a') of the first wing end (4a) rotates, so that a connection can be made to the volumes of both chambers (3a, 3b).
2. The hydraulic wing damper (1 ) as claimed in claim 1 , characterized in that the connection is made via a narrow passage through which damping medium passes only in the event of very slow changes in volume of the medium.
3. The hydraulic wing damper (1 ) as claimed in claim 2, characterized in that the narrow passage is produced by surface irregularities in the bottom side of the lid (2a) and the housing part (2b).
4. The hydraulic wing damper (1) as claimed in claim 2, characterized in that the narrow passage is produced by the arrangement of an O-ring (10) in a groove (9) in the lid (2a), which groove runs along the working volume (3) and also encloses the pressurized space (6) in which the O-ring (10) and the groove (9) are mutually tailored such that, when the lid (2a) and the lower housing part (2b) are fitted together, the working volume (3) and the second space (6) are sealed against the environment, but not against each other.
5. The hydraulic wing damper (1 ) as claimed in any one of the above claims, characterized in that a channel (11) is accommodated between the working chamber (3) and the second space (6).
6. The hydraulic wing damper (1 ) as claimed in claim 5, characterized in that the channel (11 ) is accommodated in the dividing plane between the lid (2a) and the lower housing part (2b).
7. The hydraulic wing damper (1 ) as claimed in claim 6, characterized in that the channel (11 ) is shallow, preferably between 0.01 and 0.1 mm.
8. The hydraulic wing damper (1 ) as claimed in claim 5, characterized in that the channel (11 ) is divided into a first (11a) and a second (11 b) channel part by a substantially vertical hole (12), having a diameter (d1 ), bored in the lower housing part (2b) from the dividing plane between the lid (2a) and the lower housing part (2b).
9. The hydraulic wing damper (1 ) as claimed in claim 8, characterized in that the first channel part (11a), which extends between the cutout (2c) in the housing and the hole (12), has a diameter (d2) which is larger than the diameter (d3) of the second channel part (11 b), which extends between the hole (12) and the volume-receiving space (6), the diameter (d2) of the first channel (11a) preferably being around five times as large as the diameter (d3) of the second channel (11 b).
10. The hydraulic wing damper (1 ) as claimed in claim 9, characterized in that in the hole (12) there is disposed a roller or a rod (13) having a diameter (d4) about 5% smaller than the diameter (d1 ) of the hole (12).
11. The hydraulic wing damper (1 ) as claimed in any one of the above claims, characterized in that in the center of the wing (4) there is disposed a cavity (5), the center line of which coincides with the rotation axis (RA) of the wing end (4a), the cavity is sealed against the narrow passage between the bottom side of the lid (2a) and the top side of the housing part (2b) with an O-ring (5a).
12. The hydraulic wing damper (1) as claimed in any one of the above claims, characterized in that the wing damper (1 ) is used as a steering damper for a vehicle having a handlebar in which the rotation axis (RA) and the center of the cavity (5) of the wing (4) coincide with the steering axle of the handlebar.
13. The hydraulic wing damper (1 ) as claimed in claim 11 , characterized in that the cavity (5) is arranged to cooperate with the steering column of a vehicle. |
Wing damper with pressure equalization
Technical field
The invention relates to a hydraulic wing damper with built-in pressure equalization designed for use on a two or four-wheeled vehicle. The damper is made up of an outer housing in which an oil chamber is configured. The oil chamber is divided into two chambers by a demarcating arm rotatable about a first end. At the first end of the arm there is fixed a lever, which rotates with said demarcating arm in relation to said outer housing. Connected to the oil chamber is a space designed to compensate for the change in volume of the damping medium due to a change in temperature of the medium.
Background of the invention By way of proposal, a wing damper can be fitted between the rotary handlebar of a vehicle and its fixed frame or chassis to dampen shocks and violent movements which are transmitted from the front wheel(s) to the handlebar, i.e. the damper is used as a steering damper. Where the steering damper is used on a motor cycle, it can also solve the problem of wobbling, which can occur in a motor cycle at high speeds. Wobbling means that the front wheel of the motor cycle begins to oscillate with increasing amplitude about the steering axle. Where the steering damper is used on a four-wheeled all-terrain vehicle, a so-called ATV, the steering damper is primarily designed to dampen out the rapid steering movements caused by, for example, an asymmetrical load upon the wheels. A wing damper can also be used for other vehicle-specific applications, for example to dampen a movement between a wheel and a chassis.
When a hydraulic damper is warmed due to ambient temperature or an extremely large amount of supplied damping energy as a result of the large number of rapid steering movements, the volume of the damping medium in the main chamber increases. In order to compensate for this volume
increase, a space in the form of an external container or a built-in cavity can be connected to the main chamber. The space can contain a piston and a spring acting against the piston or a compressible medium, for example a gas. In the event of volume expansion, the piston moves, so that a larger main volume is formed. When the damping medium then cools down again, the piston returns into its ordinary position and the main volume is reduced again.
In the prior art, for example US 2004211632 and WO 2005035349, two types of wing damper having an extra space for volume change compensation are shown.
In US 2004211632, a steering damper is described in which a rotary wing divides a chamber. Damping is produced by the fact that the damping medium in the respective chambers is pressed via channels between one and the other. Connected to one of these channels is a space in which a spring-pressurized piston is arranged. To ensure that damping medium will only be pressed into the space in the event of a volume increase in the damping medium, non-return valves are connected to the respective damping chambers. This non-return valve solution is complicated and generates a large number of components for the damper. It is therefore difficult to reduce the production costs of the product.
In WO 2005035349, a steering damper in the form of a double-armed wing damper is described, in which a rotary double wing and two wall parts delimit a damping housing in four chambers. An external container is directly connected to two of the chambers via a channel narrower than the damping channels which are disposed between the chambers and which produce the damping. Since the container is only connected to two of the chambers, cavitation can arise in, since the pressure conditions in the damping chambers can become imbalanced in relation to one another.
Object of the invention
The object of the present invention is to solve the problem involving a change in volume of the damping medium in a wing damper due to a change in temperature of the same.
The invention also sets out to solve this problem in an economical manner which neither leads to cavitation in the damper.
Summary of the invention The invention relates to a hydraulic wing damper designed for use on a two or four-wheeled vehicle. The wing damper comprises an outer housing consisting of an upper lid and a lower housing part, which together enclose a damping-medium-filled chamber divided by a demarcating wing into two chambers, each with its own working volume. The wing is rotatable about a first wing end and the outer face of the wing end rotates in a custom-made cutout in the lower housing part. In the first wing end there is fixed a first end of a lever, the lever rotates with the wing about the first lever end in relation to said outer housing. Connected to the oil chamber there is arranged a pressurized space having a certain volume designed to be used to compensate for the change in volume of the damping medium due to a change in temperature of the medium. In order to minimize the risk of cavitation, the space for pressure compensation is arranged directly connected to the cutout in the housing, in which cutout the outer face of the first wing end rotates, so that a connection can be made to the volumes of both chambers.
The connection is made via a very narrow passage over a long distance in relation to the size of the damping chambers, through which damping medium passes only in the event of very slow changes in volume of the medium. This since, in normal use of a hydraulic damper, the warming up and cooling down of the damping medium take place slowly. Therefore, the volume change then also takes place slowly. When the wing damper works
- A - normally and presses damping medium between the chambers, it occurs for very short time intervals, preferably fractions of a second, so that the damping medium, due to its viscosity, does not manage to flow in through the very narrow passage in the space for pressure compensation. The damping medium is therefore prevented from being pumped into the space for pressure compensation during normal use, without the need to use an advanced non-return valve solution.
In one embodiment of the damper, the narrow passage is produced between the upper face of the housing and the lid. The narrow passage is produced by the arrangement of an O-ring in a groove in the lid, which groove runs along the working volume and also encloses the pressurized space. The O-ring and the groove are mutually tailored such that, when the lid and the lower housing part are fitted together, the working volume and the volume-receiving volume are sealed against the environment, but not against each other. The narrow passage then consists only of surface irregularities on the bottom side of the lid and the top side of the housing.
In another embodiment, an extra channel is accommodated between the working chamber and the volume-receiving space. This embodiment is applicable to wing dampers which are exposed to considerable changes of temperature, for example wing dampers designed for use on desert vehicles. The extra channel then increases the prospects of through-flow of damping medium when the volume increases or decreases. The channel can be accommodated in the dividing plane between the lid and the lower housing part and is shallow.
A further alternative embodiment of the channel extending between the working chamber and the volume-receiving space can be that the channel is divided into a first and a second channel part by a vertical hole bored in the lower housing part. The hole extends from the dividing plane between the lid and the lower housing part. The first channel part, which extends
between the cutout in the housing and the vertical hole, has a diameter which is larger than the diameter of the second channel part, which extends between the vertical hole and the volume-receiving space.
By arranging in the vertical hole a roller or a rod having a diameter less than the diameter of the vertical hole, a simple valve function is obtained, which, upon transfer of the working medium from the working volume to the volume-receiving space, constitutes a restriction which is greater than that which is obtained in a flow from the volume-receiving space back to the working volume. This means that the damping medium finds it harder to flow from the damping chambers to the space than vice versa. A possible unwanted leak flow into the volume-receiving space can then be more easily prevented.
Through the arrangement of a cavity in the center of the wing and the sealing of the latter against the narrow passage between the bottom side of the lid and the top side of the housing part, a further restriction of the possible flow of damping medium between the main chamber and the second space is produced. This cavity can also be arranged to cooperate with a steering column for a vehicle having a handlebar.
The invention is described in greater detail below, with references to the accompanying drawings.
List of figures
Fig. 1a shows a side view of a first embodiment of the whole of the steering damper 1 according to the invention. Fig. 1 b shows the lid of the steering damper. Figure 1c shows a view of the lower housing of the steering damper. Fig. 2 shows a second embodiment of the damper. Fig. 3 shows a third embodiment of the damper.
Detailed description of the invention
Figure 1a shows how the steering damper looks in the lateral direction through a vertical section along the line of symmetry. The steering damper 1 comprises an outer housing 2 consisting of a lid 2a and a bottom part 2b enclosing an oil-filled main chamber 3.
Connected to the oil chamber 3 there is arranged a pressurized second space 6 having a certain volume designed to be used to compensate for a change in volume of the damping medium due to a change in temperature of the medium. The second space 6 is arranged directly connected to the cutout 2c in the housing 2, in which cutout the outer face 4a' of the first wing end 4a rotates, so that a connection can be made to the volumes of both chambers 3a, 3b. In the first wing end 4a there is fixed a first end of a lever 4b. The lever 4b is fixed at its other end in a non-rotary vehicle chassis C, and rotates with the wing 4 about a rotation axis RA substantially centered in the first lever end 4a in relation to said outer housing 2. Said outer housing 2 is secured in a device S, which moves with the handlebar (not shown) of the vehicle. Hence, when the handlebar of the vehicle is turned about a steering axle, which preferably coincides with the rotation axis RA of the wing 4, the outer housing 2 of the steering damper rotated with substantially the same movement as the handlebar about the wing 4 disposed in the housing 2, which wing is fixed in relation to the vehicle chassis C.
The second space 6 contains a piston 7 and a spring 8 acting against the piston. In the event of warming, the volume of the space is able to take up the expanding oil volume through the piston 7 tube, so that a larger volume is formed. When the working medium of the damper subsequently cools down, the spring 8, via the piston 7, forces back the medium, so that cavitation is avoided in the working chambers. The spring can also in certain cases be replaced by a medium more compressible than oil, for example air. In this case, an intake air valve (not shown) is also connected
to the space 6.
Fig. 1b shows the lid 2a from below. A groove 9 for an O-ring 10 forming a seal between the housing 2b and the lid 2a runs along the working volume 3, but also encloses the second space 6 with its piston 7 and spring 8. When the lid 2a is fitted, a very narrow passage is obtained between the working volume and the second volume, which is produced by the surface irregularities on the bottom side of the lid and the top side of the housing.
Figure 1c shows a view of the lower housing 2b. In the lower housing 2b there is arranged a wing 4, which divides the main volume 3 into two chambers 3a, 3b. The wing 4 is rotatable about the first wing end 4a, the outer face 4a' of which rotates in the cutout 2c in the lower housing 2b. Extending through both the lid 2a, the lower housing 2b and the wing 4 is a cavity 5, the center line of which coincides with the rotation axis RA of the wing end 4a. Through the arrangement of this cavity 5 in the center of the wing and the sealing thereof with an upper and a lower seal 5a, disposed in the groove 5a', against the narrow passage between the lid 2a and the lower housing 2b, the possible passage is narrowed. A narrowing of the passage increases the restriction of the flow between the main chamber and the second space and ensures that the damping medium only has a chance to flow to the space 6 when the velocities are slow. The cavity 5 can also be used in the fitting of the wing damper to a vehicle where, for example, a steering column can be introduced into the cavity 5 and a lower installation height of the damper is then possible.
In figure 2, an alternative embodiment of the housing 2b is shown, in which in the dividing plane between the lid 2a and the housing 2b there is arranged a shallow channel 11 , which can preferably be 0.01 to 0.1 mm deep. This channel joins the working volume 3 to the second space 6. Also shown in the figure is the groove 9' in which the O-ring 10 affixes the housing 2b.
Figures 3a and 3b show a further alternative embodiment of the invention, in which a single valve 13 is arranged to partially restrict the flow in the channel 1 1. The valve gives a very much greater restriction of the medium flow when the working medium is transferred in a first direction from the working volume 3 to the second space 6 than when the working medium flows in a second direction from the second space 6 back to the working volume 3. In figures 3a and 3b, the flow is going in the first direction.
The valve function is produced by the fact that the channel 1 1 is divided into a first 11a and a second 11b channel part by a vertical hole 12 bored in the lower housing part 2b. The hole 12, which preferably has a diameter d1 of 2.1 mm and is 15 mm deep, extends from the dividing plane between the lid 2a and the lower housing part 2b. The first channel part 11a, which extends between the cutout 2 in the housing 2 and the vertical hole 12, has a diameter d2 which is larger than the diameter d3 of the second channel part 11 b, which extends between the vertical hole 12 and the second space 6. Preferably, the diameter d2 of the first channel part 11a is around five times as large as the diameter d3 of the second channel part 11 b. Preferably, the diameter d2 of the first channel part 11a is 2.1 mm and the diameter d3 of the second channel part 1 1 b is about 0.4-0.6 mm.
In the vertical hole there is disposed a roller or a rod 13 having a diameter d2 about 5% smaller than the diameter d1 of the vertical hole 12. The fact that the rod 13 is somewhat smaller than the hole 12 allows it to move in the hole 12. When the working medium is transferred in the first direction from the working volume 3 to the second space 6, the rod is moved by the pressure from the damping medium to bear against the second channel part 11 b, and vice versa when the working medium flows in the other direction from the second space 6 back to the working volume 3. Since the diameter d2 of the first channel part 11a is larger than the diameter d3 of the second channel part 1 1b, the rod 13 will cover a smaller area of the first
channel part 1 1a than of the second channel part 11 b when the rod 13 is bearing against the parts. The working medium will therefore then be able to flow more easily in the second direction than in the first.
The invention is not limited to the embodiment shown above by way of example, but can be modified within the scope of the following patent claims and the inventive concept.