Bypass valve for use in well bores

A valve comprising:

• a housing having an outer wall with at least one outlet formed therethrough;
• a piston disposed within the outer wall and drivable with respect to the housing in a first direction, the piston having a fluid channel formed in an interior thereof;
• and
• a control arrangement comprising:
• a rotating element which is rotatable with respect to the housing and the piston and is spring-biased in a second direction that is opposite the first direction, and
• a driving member which is adapted to drive against the rotating element, the control arrangement being such that:
• in a first rotational orientation of the rotating element, the piston may be driven with respect to the housing in the first direction so that the driving member moves with respect to the rotating element and contacts the rotating element to exert a driving force against the rotating element which tends to drive the rotating element away from a rest position of the rotating element in a direction substantially parallel with the first direction, and relative motion between the piston and the housing is halted by the rotating element contacting a first stop element, during which motion the piston remains in a first position or range of positions relative to the housing;
• and
• in a second rotational orientation of the rotating element, the piston may be driven with respect to the housing in the first direction so that the piston reaches a second position relative to the housing where relative motion between the piston and the housing is halted by the rotating element contacting a second stop element, wherein
• the spring bias of the rotating element returns the rotating element toward the rest position once the driving force is removed.