Shock absorbers for a vehicle

Abstract

The invention relates to a shock absorber (1) for a vehicle. The shock absorber (1) comprises a primary piston (7) in a primary cylinder (6), a secondary cylinder (11) arranged in the primary cylinder (6) and connected to the primary piston (7), a secondary piston (3) in the secondary cylinder (11), and a valve (15) which is actuated depending on the position of the secondary piston (3) in the secondary cylinder (11).

Description

[0001] The invention relates to a shock absorber for a vehicle according to the features of the preamble of claim 1.

[0002] As described in DE 103 60 140 A1, a damping device for a motor vehicle is known from the prior art, which dampens relative movements occurring between a wheel and a vehicle body. The damping device has a first damping element comprising a damper housing filled with a working medium, in which a piston is arranged that divides the volume of the damper housing into two working chambers. A piston rod is connected to the piston. The damping device also has a second damping element arranged parallel to the first damping element. The second damping element is arranged in the piston rod and is connected to the two working chambers via bypass bores running through the piston rod.

[0003] German patent DE 10 2022 000 444 A1 describes a shock absorber for a vehicle. The shock absorber comprises a frequency-selective valve by means of which mechanical vibrations supplied to a shock absorber piston movably arranged in a shock absorber housing can be damped with frequency resolution by adjusting the free cross-section of a flow channel of the shock absorber piston. The shock absorber further comprises a solenoid valve arranged in the same flow channel as the frequency-selective valve. A magnet is arranged on or in the shock absorber piston. An electrical coil is arranged on or in the shock absorber housing such that the magnet moves past the coil during movement of the shock absorber piston and induces a voltage in the coil.The coil is coupled to a control unit for controlling the solenoid valve, whereby the control unit determines an excitation frequency of the shock absorber piston based on output signals from the coil, closes the solenoid valve if the excitation frequency falls below a setpoint, and opens the solenoid valve if the setpoint is exceeded.

[0004] The invention is based on the objective of providing a shock absorber for a vehicle that is improved compared to the prior art.

[0005] The problem is solved according to the invention by a shock absorber for a vehicle having the features of claim 1.

[0006] Advantageous embodiments of the invention are the subject of the dependent claims.

[0007] A shock absorber for a vehicle comprises a primary cylinder, which can be attached to the vehicle and is filled with a working fluid. A primary piston is movably arranged within the primary cylinder, dividing its primary working chamber into a first primary working chamber and a second primary working chamber. A piston rod, which can be attached to the vehicle, is connected to the primary piston. The working fluid is, in particular, an oil, especially a hydraulic oil.

[0008] The primary piston has at least one primary channel that runs through the primary piston from the first primary working chamber to the second primary working chamber.

[0009] In the second primary working chamber, a secondary cylinder filled with the working medium is arranged on the primary piston, in particular attached to it or at least partially formed together with the primary piston. A secondary piston is movably arranged in the secondary cylinder, dividing a secondary working chamber of the secondary cylinder into a first secondary working chamber and a second secondary working chamber.

[0010] A secondary channel runs through the primary piston from the first primary working chamber to the first secondary working chamber. The secondary cylinder has an opening in an end region of the second secondary working chamber facing away from the first secondary working chamber, for example in a side wall of the secondary cylinder or in an end wall of the secondary cylinder facing away from the first secondary working chamber.

[0011] According to the invention, a connecting channel to the second primary working chamber is formed in a channel wall of the secondary channel. This connecting channel has a cross-sectional area that is smaller than the opening cross-section of the opening and larger than the cross-sectional area of ​​the primary channel of at least one primary channel. Multiple primary channels may also be present. In this case, the cross-sectional area of ​​the connecting channel is larger than the cross-sectional area of ​​each of the primary channels. For example, the cross-sectional area of ​​the connecting channel is then also larger than the combined cross-sectional area of ​​all primary channels.

[0012] For example, the cross-sectional area of ​​a secondary channel is larger than the cross-sectional area of ​​a connecting channel. The cross-sectional area of ​​a secondary channel is, for example, equal to the cross-sectional area of ​​the opening. The cross-sectional area of ​​a secondary channel is, for example, larger than the combined cross-sectional area of ​​all primary channels.

[0013] A controllable valve is arranged in the connecting channel. This valve can be controlled in such a way that it can be moved into an open position for a predetermined opening time before the secondary piston reaches its respective end stop in the secondary cylinder, and can be moved back into a closed position after the predetermined opening time has elapsed.

[0014] The specified opening time is, for example, at least 10 ms to 30 ms, in particular at least 20 ms, and / or a maximum of 80 ms to 100 ms, in particular a maximum of 90 ms.

[0015] The actuator to move the valve to the open position is triggered when the secondary piston is at a predetermined distance from the respective end stop. This predetermined distance corresponds, for example, to 5% of the total length of the secondary working chamber.

[0016] In one embodiment, a first induction coil, which has an iron core, and a second induction coil, which also has an iron core, are each connected to the valve for actuating the valve. The valve can be actuated by a valve opening voltage induced in the respective induction coil, i.e., it can be moved into the open position for the predetermined opening time, in particular briefly, and moved back into the closed position after the predetermined opening time has elapsed.

[0017] The induction coils are integrated into the side wall of the secondary cylinder.

[0018] Furthermore, in this embodiment, a first permanent magnet and a second permanent magnet are arranged on the secondary piston.

[0019] The first induction coil and the first permanent magnet are arranged such that the first permanent magnet moves past the first induction coil before, and in particular shortly before, the secondary piston reaches a first end stop in the secondary cylinder facing away from the second secondary working chamber, thereby inducing the valve opening voltage in the first induction coil.

[0020] The second induction coil and the second permanent magnet are arranged such that the second permanent magnet moves past the second induction coil before, and in particular shortly before, the secondary piston reaches a second end stop facing away from the first secondary working chamber, thereby inducing the valve opening voltage in the second induction coil.

[0021] The respective permanent magnet thus induces the valve opening voltage into the respective induction coil when the secondary piston is at the specified distance to the respective end stop.

[0022] For example, the end of the secondary channel opening into the first secondary working chamber is closed by the secondary piston when the secondary piston is at the first end stop.

[0023] For example, the opening in the end area of ​​the second secondary working chamber facing away from the first secondary working chamber is closed by the secondary piston when the secondary piston is at the second end stop.

[0024] The shock absorber is specifically an amplitude-dependent shock absorber, whereby the described design solves the problem of a sudden increase in damping forces at larger amplitudes. The valve, which is controlled depending on the position of the secondary piston in the secondary cylinder, ensures a smooth transition to strong damping and thus improved ride comfort.

[0025] Exemplary embodiments of the invention are explained in more detail below with reference to a drawing.

[0026] This shows: Fig. 1 Schematic longitudinal section view of an embodiment of a shock absorber for a vehicle.

[0027] Fig. Figure 1 shows a schematic representation of an exemplary embodiment of a shock absorber 1 for a vehicle, wherein the shock absorber 1 is shown here in a longitudinal section.

[0028] The shock absorber 1 is, in particular, an amplitude-dependent shock absorber 1, also referred to as an amplitude-selective shock absorber 1. At small excitation amplitudes, it exhibits low damping to ensure high ride comfort; at large excitation amplitudes, on the other hand, the shock absorber 1 provides high damping to ensure driving safety. This function is achieved by a secondary working chamber 2 with a secondary piston 3, which is, in particular, easily displaceable.

[0029] The design of the shock absorber 1, described in more detail below, prevents an abrupt transition from low to high damping when the secondary piston 3 reaches its respective end stop 4, 5. This abrupt transition would be noticeable and would reduce ride comfort. The described solution makes this transition smoother and thus improves ride comfort.

[0030] The shock absorber 1 has a primary cylinder 6, which can be attached to the vehicle and is filled with a working medium. A primary piston 7 is movably arranged in the primary cylinder 6 and divides a primary working chamber 8 of the primary cylinder 6 into a first primary working chamber 8.1 (lower in the illustrated example) and a second primary working chamber 8.2 (upper in the illustrated example). By moving the primary piston 7 in the primary cylinder 6, one primary working chamber 8.1, 8.2 is enlarged and the other primary working chamber 8.2, 8.1 is reduced in size.

[0031] A piston rod 9, which can be attached to the vehicle, is connected to the primary piston 7.

[0032] The working medium is in particular an oil, especially a hydraulic oil.

[0033] The primary piston 7 has at least one primary channel 10 that runs through the primary piston 7 from the first primary working chamber 8.1 to the second primary working chamber 8.2. In the example shown, the primary piston 7 has several such primary channels 10, i.e., at least two; however, there may also be further primary channels 10 not shown due to the longitudinal section view.

[0034] In the second primary working chamber 8.2, a secondary cylinder 11, also filled with the working medium, is arranged on the primary piston 7, in particular attached to it or at least partially formed together with the primary piston 7. The aforementioned secondary piston 3 is movably arranged in the secondary cylinder 11, dividing the secondary working chamber 2 of the secondary cylinder 11 into a first secondary working chamber 2.1 (lower in the illustrated example) and a second secondary working chamber 2.2 (upper in the illustrated example). By moving the secondary piston 3 in the secondary cylinder 11, one secondary working chamber 2.1, 2.2 is enlarged and the other secondary working chamber 2.2, 2.1 is reduced in size.

[0035] A secondary channel 12 runs through the primary piston 7 from the first primary working chamber 8.1 into the first secondary working chamber 2.1. The secondary cylinder 11 has an opening 13 in an end region of the second secondary working chamber 2.2 facing away from the first secondary working chamber 2.1, in the illustrated example in a side wall of the secondary cylinder 11 or in other embodiments, for example in an end wall of the secondary cylinder 11 facing away from the first secondary working chamber 2.1, in particular an upper one.

[0036] A connecting channel 14 to the second primary working chamber 8.2 is formed in a channel wall of the secondary channel 12. This connecting channel 14 has a connecting channel cross-section that is smaller than the opening cross-section of the opening 13 and larger than the primary channel cross-section of the at least one primary channel 10. In the case of several primary channels 10, as in the example shown, the connecting channel cross-section of the connecting channel 14 is larger than the primary channel cross-section of each of the primary channels 10. For example, the connecting channel cross-section of the connecting channel 14 is also larger than the combined cross-section of all primary channels 10.

[0037] For example, the cross-sectional area of ​​a secondary channel 12 is larger than the cross-sectional area of ​​the connecting channel 14. For example, the cross-sectional area of ​​a secondary channel 12 is equal to the cross-sectional area of ​​the opening 13. For example, the cross-sectional area of ​​a secondary channel 12 is larger than the total cross-sectional area of ​​all primary channels 10.

[0038] A controllable valve 15 is arranged in the connecting channel 14. This valve 15 can be controlled in such a way that it can be moved into an open valve position for a predetermined opening time before the secondary piston 3 reaches the respective end stop 4, 5 in the secondary cylinder 11, and can be moved back into a closed valve position after the predetermined opening time has elapsed.

[0039] The specified opening time is, for example, at least 10 ms to 30 ms, in particular at least 20 ms, and / or a maximum of 80 ms to 100 ms, in particular a maximum of 90 ms.

[0040] The actuator to move the valve 15 into the open position is thus activated when the secondary piston 3 is at a predetermined distance from the respective end stop 4, 5. This predetermined distance corresponds, for example, to 5% of the total length of the secondary working chamber 2.

[0041] In the illustrated embodiment, a first induction coil 16, which has an iron core, and a second induction coil 17, which also has an iron core, are each connected to the valve 15 for controlling it, in particular via a control line. The valve 15 can be controlled by a valve opening voltage induced in the respective induction coil 16, 17, i.e., it can be moved into the open position for the predetermined opening time, in particular briefly, and moved back into the closed position after the predetermined opening time has elapsed.

[0042] The induction coils 16, 17 are integrated into the side wall of the secondary cylinder 11.

[0043] Furthermore, in the illustrated embodiment, a first permanent magnet 18 and a second permanent magnet 19 are arranged on the secondary piston 3.

[0044] The first induction coil 16 and the first permanent magnet 18 are arranged such that the first permanent magnet 18 moves past the first induction coil 16 before, in particular shortly before, the secondary piston 3 reaches the first end stop 4 in the secondary cylinder 11, which is located away from the second secondary working chamber 2.2 and is lower in the example shown, and thereby induces the valve opening voltage in the first induction coil 16.

[0045] The second induction coil 17 and the second permanent magnet 19 are arranged such that the second permanent magnet 19 moves past the second induction coil 17 before, in particular shortly before, the secondary piston 3 reaches the second end stop 5, which is the upper end stop in the example shown and is facing away from the first secondary working chamber 2.1, and thereby induces the valve opening voltage in the second induction coil 17.

[0046] In Fig. Figure 1 shows the secondary piston 3 in its first end stop 4 using solid lines. Additionally, the position of the secondary piston 3 in its second end stop 5 is shown using dashed lines.

[0047] In the illustrated example, the first permanent magnet 18 is arranged on a piston end face facing the second secondary working chamber 2.2, in particular the top side, or in an adjacent area of ​​the secondary piston 3. In the illustrated example, the second permanent magnet 19 is arranged on a piston end face facing the first secondary working chamber 2.1, in particular the bottom side, or in an adjacent area of ​​the secondary piston 3.

[0048] In the illustrated example, the permanent magnets 18, 19 are arranged opposite each other, but at different heights, on the secondary piston 3 in the transverse direction of the shock absorber 1. In the illustrated example, the induction coils 16, 17 are arranged opposite each other, but at different heights, in the side wall of the secondary cylinder 11 in the transverse direction of the shock absorber 1. In the illustrated example, the second induction coil 17 is offset from the first induction coil 16 in the direction of the second secondary working chamber 2.2.

[0049] In the illustrated example, the first induction coil 16 is arranged such that it is located at the second secondary working chamber 2.2 when the secondary piston 3 is at the first end stop 4, and at the first secondary working chamber 2.1 when the secondary piston 3 is at the second end stop 5. In the illustrated example, the second induction coil 17 is arranged such that it is located at the first secondary working chamber 2.1 when the secondary piston 3 is at the second end stop 5, and at the second secondary working chamber 2.2 when the secondary piston 3 is at the first end stop 4.

[0050] The respective permanent magnet 18, 19 thus induces the valve opening voltage into the respective induction coil 16, 17 when the secondary piston 3 is at the specified distance to the respective end stop 4, 5.

[0051] For example, an end of the secondary channel 12 opening into the first secondary working chamber 2.1 is closed by the secondary piston 3 when the secondary piston 3 is at the first end stop 4.

[0052] For example, the opening 13 in the end region of the second secondary working chamber 2.2, facing away from the first secondary working chamber 2.1, is closed by the secondary piston 3 when the secondary piston 3 is at the second end stop 5.

[0053] In the described and in Fig.In the exemplary solution shown in Figure 1 for achieving a smooth transition from low to high damping, the secondary piston 3 thus has two permanent magnets 18, 19, located on opposite sides of the secondary piston 3 in the illustrated example, and two induction coils 16, 17, each with an iron core, are integrated into the side wall of the secondary cylinder 11 in the secondary working chamber 2. The induction coils 16, 17 act as sensors and control the valve 15, which is a proportional valve.

[0054] As the primary piston 7 moves towards the second primary working chamber 8.2, thus upwards in the illustrated example (in the direction of travel), the secondary piston 3 moves in the secondary working chamber 2 towards the first secondary working chamber 2.1, thus downwards in the illustrated example. The first induction coil 16, which acts as a sensor, is positioned such that before, and in particular shortly before, the secondary piston 3 reaches the first end stop 4 (lower in the illustrated example), the first permanent magnet 18 induces a voltage, i.e., the valve opening voltage, in the first induction coil 16.

[0055] With this voltage signal, the valve 15 opens the connecting channel 14 between the first primary working chamber 8.1 (lower in the illustrated example) and the second primary working chamber 8.2 (upper in the illustrated example) for the specified opening time, in particular briefly. The working medium can then flow from the second primary working chamber 8.2 into the first primary working chamber 8.1 via this connecting channel 14 and the secondary channel 12.

[0056] In this way, and due to the cross-sections of the connecting channel 14, the opening 13, and the at least one primary channel 10 or the multiple primary channels 10 described above, a more uniform transition of the damping from soft to hard is achieved. Hard damping is only achieved when the valve 15 is closed again and the working medium can only flow from the second primary working chamber 8.2 into the first primary working chamber 8.1 through the at least one primary channel 10 or the multiple primary channels 10 of the primary piston 7.

[0057] The shock absorber 1 also functions accordingly when the primary piston 7 moves towards the first primary working chamber 8.1, downwards in the illustrated example, in the direction of compression. Then the secondary piston 3 moves in the secondary working chamber 2 towards the second secondary working chamber 2.2, upwards in the illustrated example. The second induction coil 17, which acts as a sensor, is positioned such that before, and especially shortly before, the secondary piston 3 reaches the second end stop 5 (the upper one in the illustrated example), the second permanent magnet 19 induces a voltage, i.e., the valve opening voltage, in the second induction coil 17.

[0058] With this voltage signal, the valve 15 opens the connecting channel 14 between the first primary working chamber 8.1 (lower in the illustrated example) and the second primary working chamber 8.2 (upper in the illustrated example) for the specified opening time, in particular briefly. The working medium can then flow from the first primary working chamber 8.1 into the second primary working chamber 8.2 via the secondary channel 12 and the connecting channel 14.

[0059] In this way, and due to the cross-sections of the connecting channel 14, the opening 13, and the at least one primary channel 10 or the multiple primary channels 10 described above, a more uniform transition of damping from soft to hard is achieved during this movement of the primary piston 7. Hard damping is only achieved when the valve 15 is closed again and the working medium can only flow from the first primary working chamber 8.1 to the second primary working chamber 8.2 through the at least one primary channel 10 or the multiple primary channels 10 of the primary piston 7.

[0060] It is particularly intended, especially in the embodiment shown, that the valve 15 is or is switched in such a way that it opens only every second induction of the valve opening voltage for the predetermined opening time, i.e. it can be moved into the open valve position for the predetermined opening time and can be moved back into the closed valve position after the predetermined opening time has elapsed.This prevents the valve 15 from opening again during the return movement of the secondary piston 3 from the lower first end stop 4 to the upper second end stop 5 when the first permanent magnet 18 moves past the first induction coil 16 again and induces the valve opening voltage in the first induction coil 16 again. Likewise, this prevents the valve 15 from opening again during the return movement of the secondary piston 3 from the upper second end stop 5 to the lower first end stop 4 when the second permanent magnet 19 moves past the second induction coil 17 again and induces the valve opening voltage in the second induction coil 17 again.

Claims

[1] Shock absorber (1) for a vehicle, comprising a primary cylinder (6) attachable to the vehicle and filled with a working medium, in which a primary piston (7) is movably arranged, which divides a primary working chamber (8) of the primary cylinder (6) into a first primary working chamber (8.1) and a second primary working chamber (8.2), wherein a piston rod (9) attachable to the vehicle is connected to the primary piston (7), wherein - the primary piston (7) has at least one primary channel (10) which extends through the primary piston (7) from the first primary working chamber (8.1) to the second primary working chamber (8.2), - in the second primary working chamber (8.2) a secondary cylinder (11) filled with the working medium is arranged on the primary piston (7), in which a secondary piston (3) is movably arranged, which divides a secondary working chamber (2) of the secondary cylinder (11) into a first secondary working chamber (2.1) and a second secondary working chamber (2.2), - a secondary channel (12) runs through the primary piston (7) from the first primary working chamber (8.1) into the first secondary working chamber (2.1), and - the secondary cylinder (11) has an opening (13) in an end area of ​​the second secondary working chamber (2.2) facing away from the first secondary working chamber (2.1), characterized by , that - in a channel wall of the secondary channel (12) a connecting channel (14) to the second primary working chamber (8.2) is formed, - the connecting channel (14) has a connecting channel cross-section that is smaller than an opening cross-section of the opening (13) and larger than a primary channel cross-section of the at least one primary channel (10), and - a valve (15) is arranged in the connecting channel (14) which can be controlled in such a way that it can be moved into an open valve position for a predetermined opening time before the secondary piston (3) reaches a respective end stop (4, 5) in the secondary cylinder (11), and can be moved back into a closed valve position after the predetermined opening time has elapsed. [2] Shock absorber (1) according to claim 1, characterized by , that - a first induction coil (16) having an iron core and a second induction coil (17) having an iron core, are each connected to the valve (15) for controlling the valve (15), - the valve (15) can be moved into the open position for the specified opening time by a valve opening voltage induced in the respective induction coil (16, 17), - the induction coils (16, 17) are integrated into a side wall of the secondary cylinder (11), - a first permanent magnet (18) and a second permanent magnet (19) are arranged on the secondary piston (3), - the first induction coil (16) and the first permanent magnet (18) are arranged such that the first permanent magnet (18) moves past the first induction coil (16) before the secondary piston (3) reaches the first end stop (4) in the secondary cylinder (11) facing away from the second secondary working chamber (2.2), thereby inducing the valve opening voltage in the first induction coil (16), and - the second induction coil (17) and the second permanent magnet (19) are arranged such that the second permanent magnet (19) moves past the second induction coil (17) before the secondary piston (3) reaches the second end stop (5) facing away from the first secondary working chamber (2.1), thereby inducing the valve opening voltage in the second induction coil (17). [3] Shock absorber (1) according to any one of the preceding claims, characterized by , that the specified opening time is at least 10 ms to 30 ms, in particular at least 20 ms, and / or at most 80 ms to 100 ms, in particular at most 90 ms. [4] Shock absorber (1) according to any one of the preceding claims, characterized by , that the control to move the valve (15) into the open valve position occurs when the secondary piston (3) is at a distance from the respective end stop (4, 5) which corresponds to 5% of a total length of the secondary working chamber (2). [5] Shock absorber (1) according to any one of the preceding claims, characterized by , that an end of the secondary channel (12) opening into the first secondary working chamber (2.1) is closed by the secondary piston (3) when the secondary piston (3) is at the first end stop (4). [6] Shock absorber (1) according to any one of the preceding claims, characterized by , that the opening (13) in the end region of the second secondary working chamber (2.2) facing away from the first secondary working chamber (2.1) is closed by the secondary piston (3) when the secondary piston (3) is at the second end stop (5). [7] Shock absorber (1) according to any one of the preceding claims, characterized by , that there are several primary channels (10), wherein the connecting channel cross-section of the connecting channel (14) is larger than the primary channel cross-section of each of the primary channels (10). [8] Shock absorber (1) according to claim 7, characterized by, that the connecting channel cross-section of the connecting channel (14) is larger than the total cross-section of all primary channels (10).

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