1. A powered vehicle comprising:
a frame;
a seat mounted on the frame;
a pair of drive wheels positioned on opposing sides of the frame;
a drive motor operatively coupled to at least one of the drive wheels for powering rotation of the drive wheel about a drive wheel axis and for powering movement of the vehicle across a ground plane; and
at least one anti-tip assembly comprising
a suspension arm pivotably mounted to the frame at a suspension arm pivot axis, said suspension arm extending from said suspension arm pivot axis outwardly from the frame, said suspension arm pivot axis vertically spaced above the ground plane,
an anti-tip wheel assembly including an anti-tip wheel having a rotational axis about which the anti-tip wheel rotates, said anti-tip wheel assembly disposed on the extended suspension arm, the vertical position of the suspension arm pivot axis with respect to the ground plane in normal operation being spaced from and positioned relatively below a line drawn between the drive wheel axis and the rotational axis of the anti-tip wheel, and
a resilient link operatively connecting the drive motor to the suspension
wherein, in response to torque created by the motor in rotating the drive wheel, the drive motor pivots, causing through the operative connection of the resilient link the suspension arm to pivot about the suspension arm pivot axis, and causing a corresponding movement of the anti-tip assembly.
2. The vehicle of claim 1 wherein the drive motor is pivotably mounted on the frame and wherein the drive motor pivots about the mounting in response to the torque created in rotating the drive wheel.
3. The vehicle of claim 2 wherein the pivotal coupling of the drive motor to the frame is at a position substantially vertically aligned with the suspension arm pivot axis.
4. A vehicle as claimed in claim 1 wherein the resilient link has a fixed maximum length and is resiliently compressible in response to a motion of the drive motor about the pivotal mounting towards the suspension arm.
5. The vehicle of claim 1 wherein the anti-tip axis in normal operation of the vehicle is spatially located at a vertical position with respect to the ground plane substantially equal to or above the vertical position of the suspension arm pivot axis relative to the ground plane.
6. The vehicle of claim 1 further wherein the resilient link comprises at least two link members, a first link member attached to the drive motor and a second link member attached to the suspension arm, and a resilient member formed between the first and second link members.
7. The vehicle of claim 6 wherein the second link is pivotally attached to the suspension arm at a point between the suspension arm pivot and the anti-tip wheel.
8. The vehicle of claim 6 wherein one of the two link members is telescopingly received within the other of the two link members.
9. The vehicle of claim 8 wherein a pin is formed on one of the two link members, the pin projecting into a slot in another of the two link members, the engagement of the pin in the slot fowling a limit stop for the relative movement of the two link members relative to one another in one direction, resulting in the resilient link being resiliently compressible for a limited distance.
10. The vehicle of claim 6 wherein the resilient member is an elastomeric material.
11. A vehicle comprising:
a frame;
a pair of drive wheels defining a drive wheel axis, and a least one rear wheel;
a drive motor assembly pivotably coupled to the frame at a position relatively above the drive wheel axis, and operatively coupled to at least one drive wheel for powering the rotation of the drive wheel about the drive wheel axis and for powering movement of the vehicle across a ground plane; and
at least one anti-tip assembly comprising:
a suspension arm pivotably mounted to the frame at a suspension arm pivot axis that is vertically spaced above the ground plane; and
an anti-tip wheel assembly disposed proximate to an end of the suspension arm, and including an anti-tip wheel having a rotational axis about which the anti-tip wheel rotates,
wherein the vertical position of the suspension arm pivot axis with respect to the ground plane in normal operation is spaced from and positioned relatively below a line drawn between the drive wheel axis and the rotational axis of the anti-tip wheel.
12. The vehicle of claim 11 wherein the suspension arm pivots about the suspension arm pivot axis in response to torque created by the rotation of the drive wheel by the drive motor assembly and causing a corresponding vertical movement of the anti-tip wheel assembly.
13. The vehicle of claim 12 further comprising means operatively connecting the drive motor assembly to the suspension arm for operatively transferring the torque responsive movement of the drive motor assembly to the suspension arm.
14. The vehicle of claim 12 further comprising a link transferring the torque causing a pivoting of the drive motor assembly about its mounting to operatively pivot the suspension arm about the suspension arm pivot axis and causing a corresponding movement of the anti-tip assembly.
15. The vehicle of claim 14 wherein the link has a fixed maximum length and is resiliently compressible in response to a motion of the drive motor assembly about the pivotal mounting towards the suspension arm.
16. The vehicle of claim 15 wherein the pivotal coupling of the drive motor assembly to the frame is at a position substantially vertically aligned with the suspension arm pivot axis.
17. The vehicle of claim 16 wherein the anti-tip axis in normal operation of the vehicle is spatially located at a vertical position with respect to the ground plane substantially equal to or above the vertical position of the suspension arm pivot axis relative to the ground plane.
18. The vehicle of claim 14 wherein the link is resilient, the resilient link comprising at least two link members, a first link member attached to the drive motor assembly and a second link member attached to the suspension arm, and a resilient member formed between the first and second link members.
19. The vehicle of claim 18 wherein one of the two link members is telescopingly received within the other of the two link members.
20. The vehicle of claim 18 wherein a pin is formed on one of the two link members, the pin projecting into a slot in another of the two link members, the engagement of the pin in the slot forming a limit stop for the relative movement of the two link members relative to one another in one direction, resulting in the resilient link being resiliently compressible for a limited distance.
21. The vehicle of claim 18 wherein the resilient member is an elastomeric material.
22. A vehicle comprising:
a frame;
a pair of drive wheels defining a drive wheel axis, and a least one rear wheel;
a drive motor assembly pivotably coupled to the frame and operatively coupled to each drive wheel for powering the rotation of the drive wheels about the drive wheel axis and for powering movement of the vehicle across a ground plane; and
at least one anti-tip assembly comprising:
a suspension arm pivotably mounted to the frame at a suspension arm pivot axis that is vertically spaced above the ground plane; and
an anti-tip wheel assembly disposed proximate to an end of the suspension arm, and including an anti-tip wheel having a rotational axis about which the anti-tip wheel rotates,
wherein (i) the vertical position of the suspension arm pivot axis with respect to the ground plane in normal operation is spaced from and positioned relatively below a line drawn between the drive wheel axis and the rotational axis of the anti-tip wheel, and (ii) the drive motor assembly is pivotably coupled to the frame at a position vertically above the position on the frame of the suspension arm pivot.
23. The vehicle of claim 22, wherein the suspension arm pivots about the suspension arm pivot axis in response to torque created by the rotation of the drive wheel and causing a corresponding vertical movement of the ant-tip wheel assembly.
24. The vehicle of claim 23 further comprising means operatively connecting the drive motor assembly to the suspension arm for operatively transferring the torque responsive movement of the drive motor assemble to the suspension arm.
25. The vehicle of claim 23 further comprising a link transferring the torque movement pivoting the drive motor assembly about its mounting to operatively pivot the suspension arm about the suspension arm pivot axis and causing a corresponding movement of the anti-tip assembly.
26. The vehicle of claim 25 wherein the link has a fixed maximum length and is resiliently compressible in response to a motion of the drive motor about the pivotal mounting towards the suspension arm.
27. The vehicle of claim 22 wherein the anti-tip axis in normal operation of the vehicle is spatially located at a vertical position with respect to the ground plane substantially equal to or above the vertical position of the suspension arm pivot axis relative to the ground plane.
28. The vehicle of claim 25 wherein the link is resilient, the resilient link comprising at least two link members, a first link member attached to the drive motor and a second link member attached to the suspension arm, and a resilient member formed between the first and second link members.
29. The vehicle of claim 28 wherein one of the two link members is telescopingly received within the other of the two link members.
30. The vehicle of claim 29 wherein a pin is formed on one of the two link members, the pin projecting into a slot in another of the two link members, the engagement of the pin in the slot forming a limit stop for the relative movement of the two link members relative to one another in one direction, resulting in the resilient link being resiliently compressible for a limited distance.
31. The vehicle of claim 29 wherein the resilient member is an elastomeric material.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A voltage controlled oscillator comprising:
a voltage comparing circuit that receives a control voltage, a first reference voltage, and a second reference voltage to activate a first voltage comparison signal when the control voltage is lower than the first reference voltage and to activate a second voltage comparison signal when the control voltage is higher than the second reference voltage, the second reference voltage being higher than the first reference voltage;
a counter that decrements a counter value while the first voltage comparison signal is activated and increments the counter value while the second voltage comparison signal is activated, in synchronization with a count clock; and
an oscillating circuit that has a plurality of oscillation frequency bands different from one another, selects one of the oscillation frequency bands according to the counter value, and regulates an oscillation frequency according to the control voltage within the selected oscillation frequency band to output an output clock.
2. The voltage controlled oscillator according to claim 1, wherein
said oscillating circuit comprises: a plurality of internal oscillating circuits having oscillation frequency bands different from one another; and a selecting circuit that selects, according to the counter value, one of clocks generated by said internal oscillating circuits to output the selected clock as the output clock; and
each of said internal oscillating circuits comprises: a plurality of inverting circuits connected in a ring; and a plurality of variable resistors provided between a power supply line and power supply terminals of said inverting circuits to be connected with the power supply line and the power supply terminals, respectively, and changing a resistance value according to the control voltage.
3. The voltage controlled oscillator according to claim 2, wherein
in response to a reset signal, said counter is initialized to such a counter value as to designate an internal oscillating circuit having an oscillation frequency band including a target frequency of the output clock.
4. The voltage controlled oscillator according to claim 1, wherein said oscillating circuit comprises:
a plurality of inverting circuits connected in series;
a plurality of variable resistors provided between a power supply line and power supply terminals of said inverting circuits to be connected with the power supply line and the power supply terminals, respectively, and changing a resistance value according to the control voltage; and
a switching circuit that connects one of outputs of odd-numbered inverting circuits to an input of an initial inverting circuit according to the counter value in order to output, as the output clock, a signal to be supplied to the input of the initial inverting circuit.
5. The voltage controlled oscillator according to claim 4, wherein
in response to a reset signal, said counter is initialized to such a counter value as to designate an output of an inverting circuit which corresponds to the oscillation frequency band including a target frequency of the output clock.
6. The voltage controlled oscillator according to claim 1, wherein said oscillating circuit comprises:
a plurality of inverting circuits connected in a ring;
a plurality of switching circuits each having a plurality of switches connected in parallel between a power supply line and respective power supply terminals of said inverting circuits, a number of switches in an ON state in each of the switching circuits changing according to the counter value; and
a plurality of variable resistors connected in series to said switching circuits respectively between the power supply line and the power supply terminals of said inverting circuits and changing a resistance value according to the control voltage.
7. The voltage controlled oscillator according to claim 6, wherein
in response to a reset signal, said counter is initialized to such a counter value as to indicate the number of switches in the ON state which corresponds to the oscillation frequency band including a target frequency of the output clock.
8. A PLL circuit comprising:
a phase comparator comparing phases of a reference clock and of an output clock generated according to the reference clock;
a voltage regulating circuit regulating an output voltage according to a result of the phase comparison by said phase comparator; and
a voltage controlled oscillator receiving the output voltage as a control voltage to change a frequency of the output clock according to the control voltage, wherein said voltage controlled oscillator comprises:
a voltage comparing circuit receiving the control voltage, a first reference voltage, and a second reference voltage to activate a first voltage comparison signal when the control voltage is lower than the first reference voltage and to activate a second voltage comparison signal when the control voltage is higher than the second reference voltage, the second reference voltage being higher than the first reference voltage;
a counter that decrements a counter value while the first voltage comparison signal is activated and increments the counter value while the second voltage comparison signal is activated, in synchronization with a count clock; and
an oscillating circuit that has a plurality of oscillation frequency bands different from one another, selects one of the oscillation frequency bands according to the counter value, and regulates an oscillation frequency according to the control voltage within the selected oscillation frequency band to output the output clock.
9. The PLL circuit according to claim 8, further comprising
a divider provided between said voltage controlled oscillator and said phase comparator to frequency-divide the output clock to output a divided clock to said phase comparator as the output clock.
10. The PLL circuit according to claim 8, wherein:
said count clock is the output clock; and
said counter updates the counter value in synchronization with an inverse transition edge of a transition edge of the output clock which is used as a timing for the phase comparison by said phase comparator.