ERJ-145 First Officer reported encountering wake turbulence while climbing out of PHL that caused a speed deviation.

Narrative

Upon departing Philadelphia on the PHL4 Departure; as we were executing a climbing left turn; around approximately 7000 feet; we encountered wake turbulence from an aircraft above us.We were in the climb vertical mode; with the autopilot engaged.The airspeed; that was initially stabilized at 240 KIAS; started to increase slowly. Since this is something that can sometimes happen and that normally; eventually gets corrected by the autopilot; in that mode; as a speed protection feature; at first; we just monitored the airspeed.But since the airspeed kept increasing; I had to momentarily disconnect the autopilot; using the Touch Control Steering (TCS) button; in order to steepen the climb and keep the airspeed within limits.Doing this allowed me to quickly reduce the airspeed increase rate. When it completely stopped increasing; before going back down towards 240 KIAS (our target speed at that altitude); the speed tape momentarily (less than a second) indicated between 250 and 251 KIAS; and the airspeed" aural warning chimed once; and then stopped immediately.Once the airspeed was again stabilized at 240 KIAS; I released the TCS button; thus re-engaging the autopilot; selected the climb vertical mode again; and kept monitoring the airspeed closely.The rest of the flight was uneventful.Once on the ground; I called Maintenance Control to notify them of the occurrence; and was told that this event did not exceed the tolerances as far as airframe overspeed was concerned.Cause: Wake-induced turbulent air caused the autopilot's speed protection capability to be diminished. Suggestion: Monitor airspeed very closely when using climb or IAS vertical mode with autopilot engaged. Especially in turbulent conditions. And be prepared to react quickly; hand-flying if necessary."