PRAM

Abstract

Pram or pram frame, comprising at least one motor, in particular an electric motor, for the assisted driving of the pram or pram frame, a push bar for pushing the pram or pram frame, at least one force sensor device for detecting a direction and/or an amount of a force and/or a force component which acts on the push bar, and/or for detecting a variable derived from this force or force component, in particular a torque and/or a change of the force or force component over time, at least one velocity sensor device for determining a velocity of the pram or pram frame, and at least one control unit, which is configured in such a way that the motor assistance is adapted in dependence on a comparison of the measured force and/or force component and/or the variable derived therefrom to a force threshold value, wherein the force threshold value is established in dependence on a comparison of the measured velocity to a velocity threshold value.

Claims

1. A pram, comprising: at least one motor configured for assisted driving of a frame of the pram, a push bar configured for pushing the frame, at least one force sensor configured to measure a force acting on the push bar relative to the frame, and configured to provide an output corresponding to at least one of a torque, a change of the force, or a force component over time, and at least one velocity sensor for measuring a velocity of the frame, and at least one control unit configured such that a motor assistance is based on a comparison of the measured force and a force threshold value, wherein the force threshold value is based on a comparison of the measured velocity to a velocity threshold value.

2. A pram according to claim 1, comprising: at least one control unit, configured such that the motor assistance is transitioned between a present power and the target power in a time interval via at least one intermediate step or at least temporarily continuously.

3. The pram according to claim 1, wherein the control unit is configured to set a force threshold value to a first positive value if a current velocity is less than or equal to the velocity threshold value and to set it to a second positive value if the current velocity is greater than or equal to the velocity threshold value, wherein the first positive value is not equal to the second positive value.

4. The pram according to claim 1, wherein the force sensor device comprises at least one torque sensor or at least two sensors.

5. The pram according to claim 2, wherein the control unit is configured such that, when a currently measured force exceeds or reaches the force threshold value, the motor assistance is permitted, and when the currently measured force does not exceed or does not reach the force threshold value, the motor assistance is not permitted.

6. The pram according to claim 1, wherein the control unit is configured such that motor assistance is permitted if at least one wheel rotates.

7. The pram according to claim 1, wherein the control unit is configured such that motor assistance is based on the measured force and based on the measured velocity.

8. The pram according to claim 1, wherein the control unit is configured such that motor assistance is activated such that an average force applied is regulated to a force value determined based on the first force threshold value or the second force threshold value.

9. The pram according to claim 2, wherein the control unit is configured such that a transition from a first motor assistance to a second motor assistance is determined by a part of a difference between a current power and an ascertained target power.

10. The pram according to claim 3, wherein the velocity threshold value is less than 4 km/h, or the first positive value of the force threshold value is higher than the second positive value of the force threshold value or the first positive value of the force threshold value is greater than or equal to 20 N, or the second positive value of the force threshold value is between 8 N and 25 N, or a length of a time interval is at most 2 s (two seconds).

11. A method for controlling a pram according to 1.

12-18. (canceled)

Description

[0098] The invention is described hereinafter on the basis of exemplary embodiments, which are explained in more detail on the basis of the figures. In the figures:

[0099] FIG. 1 shows a flow chart of an exemplary embodiment of the present invention;

[0100] FIG. 2 shows a diagram: force over the measured velocity v;

[0101] FIG. 3 shows a diagram: adaptation P of the assistance of the electrical drive via the force F acting externally on the push bar;

[0102] FIG. 4 shows a schematic diagonal view of a pram frame according to the invention; and

[0103] FIG. 5 shows a side view of the pram frame according to FIG. 4.

[0104] FIG. 1 shows a flow chart of an exemplary embodiment of the present invention. In (optional) step S0, it is first queried whether the wheels (rear wheels), which are additionally driven by the electrical drive (the assistance), move (rotate) at all. If this is the case, it is queried in step S1 at which velocity v the pram moves.

[0105] The velocity can be determined, for example, by a separate velocity sensor, or on the basis of the current motor speed in conjunction with the physical dimensions of the wheel (rear wheel) and possible intermediate gear ratios.

[0106] In step S1, it is decided on the basis of the determined current velocity of the pram whether the force threshold value is set to its first value (for example 25 N or 30 N) (step S2a), or whether the force threshold value is set to its second value (for example 17 N) (step S2b). If the velocity in step S1 is less than the velocity threshold (for example of greater than 0.000 m/s to 0.556 m/s), the force threshold value is set to its first value, otherwise its second value is used.

[0107] In step S3, the measured current force which acts externally on the push bar is compared to the force threshold value from step S2a or S2b. If the corresponding force threshold value is not exceeded, the sequence returns to step S0. If, in step S3, the force threshold value from step S2a or S2b is exceeded, in step S4 the electrical drive is thus activated (and assistance by the electrical drive is initiated or adapted).

[0108] In FIG. 2, the force is plotted over the measured velocity v. If the measured velocity is below the velocity threshold value, the force threshold value is set to its first value F.sub.th1. If the measured velocity v is above the velocity threshold value, the force threshold value is set to its second value F.sub.th2.

[0109] In FIG. 3, an exemplary embodiment of a soft transition is shown. The adaptation P of the assistance of the electrical drive via the force F acting externally on the push bar is shown. Furthermore, the high value F.sub.th1 and the low value F.sub.th2, to which the force threshold value can be set, are shown. Three adaptation stages P.sub.s1, P.sub.s2, and P.sub.s3 are shown.

[0110] FIG. 4 shows a pram frame according to the invention in a schematic diagonal view. The arrows F.sub.d show a downward-directed force engaging on a handle 13 (horizontal section of a push bar 10). The arrow F.sub.u shows an upward-directed force engaging on the handle 13. The arrows F.sub.lat show laterally directed forces. The handle 13 is pivotably mounted in relation to a lower section of the push bar 10.

[0111] Specifically, the handle 13 can be pivoted (and locked) into various positions to carry out a vertical adjustment of the handle 13.

[0112] A pivotable mounting 12 (having corresponding joints) is provided between the pivotable handle 13 and the lower section of the push bar 10.

[0113] The (entire) push bar 10 is in turn preferably pivotably mounted on a pivotable mounting 11 on a main body of the pram frame (in particular to be able to collapse the pram frame).

[0114] A sensor device/sensor devices is/are preferably provided in the pivotable mounting 11 and/or in the pivotable mounting 12, in order to detect a force of a user (in particular F.sub.u and F.sub.d) acting on the handle 13. Furthermore (see FIG. 5), a forward-directed force F.sub.f and a backward-directed force F.sub.r can preferably be detected using such a sensor device or such sensor devices. Motors (not recognizable in detail) can preferably be placed in wheel hubs 21. Alternatively, motors can be placed on an axle 22 (in particular on sections of the axle which are adjacent to the wheel hub 21).

[0115] It is to be noted here that all above-described parts are claimed as essential to the invention considered as such and in any combination, in particular in the details illustrated in the drawings. Modifications thereof are routine to a person skilled in the art.

LIST OF REFERENCE SIGNS

[0116] F force which acts on the push bar of the pram [0117] F.sub.th1 first value of the force threshold value [0118] F.sub.th2 second value of the force threshold value [0119] P adaptation of the assistance, for example in percent with respect to the maximum possible assistance [0120] Ps1 adaptation stage [0121] Ps2 adaptation stage [0122] Ps3 adaptation stage [0123] v currently detected velocity of the pram; [0124] S0 querying whether the rear wheels of the pram rotate; [0125] S1 querying whether the current velocity is in a low range; [0126] S2a setting the force threshold value to a high value; [0127] S2b setting the force threshold value to a low value; [0128] S3 querying whether the force threshold value is exceeded; and [0129] S4 activating the electrical drive. [0130] 10 push bar [0131] 11 pivotable mounting [0132] 12 pivotable mounting [0133] 13 handle (horizontal section of the push bar) [0134] 21 wheel hub [0135] 22 axle